SETI spots dozens of new mysterious signals emanating from distant galaxy | Hacker News Reader

SETI spots dozens of new mysterious signals emanating from distant galaxy

techcrunch.com

798 pointsvfc1528 comments

I have a question... and this is probably a stupid question, but... does anyone know if there is any theory to support the idea that sufficiently advanced civilizations rely on something other than radio waves or light to perform communications? My dumbass-self wonders about quantum entanglement or teleportation as means of communication we have yet to master; may be, the medium of communications for the super civilizations of the universe.

Note: Just wanted to say, I'm less trying to talk about "FTL" and more so that we may just not be able to intercept, decode, or "see" the communications via our current technologies.

P.S. Thanks for the thoughtful replies.

I think this goes back to searching for other life on earth-like planets. We know what life looks like on our planet, so that's really the only thing we have to go off of, otherwise we are stabbing in the dark.

Likely we are searching for radio waves and light since that's the only thing we know how to communicate with.

It is more than that. We know what life looks like: composed of carbon because that is the only atom than easily forms long chains of double bonds. It is also very likely to be composed of the atoms that are common in the universe: the low Atomic number ones.

Also, liquid water is very convenient for complex chemistry.

It’s by definition stuff that we don’t know about, so we can’t exactly go looking for it.

"I am old, older than thought in your species, which is itself fifty times older than your history. Though I have been on earth for ages I am from the stars. My home is no one planet, for many worlds scattered through the shining disc of the galaxy have conditions which allow my spores an opportunity for life. The mushroom which you see is the part of my body given to sex thrills and sun bathing, my true body is a fine network of fibers growing through the soil. These networks may cover acres and may have far more connections that the number in a human brain. My mycelial network is nearly immortal, only the sudden toxification of a planet or the explosion of its parent star can wipe me out. By means impossible to explain because of certain misconceptions in your model of reality all my mycelial networks in the galaxy are in hyperlight communication across space and time. The mycelial body is as fragile as a spider's web but the collective hypermind and memory is a vast historical archive of the career of evolving intelligence on many worlds in our spiral star swarm. Space, you see, is a vast ocean to those hardy life forms that have the ability to reproduce from spores, for spores are covered with the hardest organic substance known."

Terence McKenna Psilocybin - Magic Mushroom Grower's Guide

Reads like it was written by machine elves...

It depends on whether you want to stay grounded in real-world physics, or if you want to spin off on flights of fancy.

If you want to stay in real-world physics, at the moment there is no reason to expect any civilization to use anything other than electromagnetic radiation for communication. Other than the low speed of light, which is a characteristic of the universe that it does not seem to allow any faster-than-light communication so it's not specially a disadvantage for EM, electromagnetic radiation basically has every characteristic you're looking for in a communications medium, and there's little reason to believe even an advanced civilization would use something orders of magnitude worse on numerous dimensions simply because maybe they can. This is for much the same reason that we could transport everything in our civilization by people carrying things around on Segways, but we don't, because why would we deliberately choose something suboptimal?

If you want to go off on flights of fancy, then anything is possible, but there's no way to say anything useful about it.

The "grounded in reality" answer is subject to change as our understanding of physics improves, but at the moment I wouldn't say there's any particular reason to expect this answer to change much. Even on the crazy fringe frontiers of real science, I am not aware of any candidates for communication any better than EM.

Most of the whacky ideas proposed as alternate methods fail by orders of magnitude vs EM. Might you be able to build a better neutrino detector than we can? Maybe, but it's still easier to build EM detectors, and EM emitters, by a lot. Gravity waves? Why on not-Earth would anyone spend the massive, massive amounts of energy required to do that, very klunkily and with very low bandwidth, when for literally a trillionth of a trillionth of a trillionth of a trillionth the energy expenditure you could use EM, and get higher bandwidth to boot and better reusability to boot? Quantum entanglement and teleportion are non-starters, because they both require a conventional channel to work at all, and the best tool for that communication is EM.

I think the parent meant -- or a least a steelman of the point would be -- whether there could be some kind of particle/field/force/form-of-energy we're missing out on that could be used to communicate (even if slower than light), and whether there's some way to rule that out. I don't think that's dismissable as being a flight of fancy any more than the existence of radio waves would have been in 1500.

Well, we already know that we don't know what dark matter is. Something might be hiding in there which is useful for communication.

We do not know what dark matter is, but we do know several things it is not. Among the things that it can not be is terribly strongly interacting with itself. We know this because dark matter appears to surround galaxies with spherical halos, rather than in discs. If it did strongly or even moderately self-interact, it would also be in the disc, because that's precisely why normal matter galaxies are in a disc.

So this excludes, for instance, the idea that there are dark matter civilizations using dark matter machines to send some sort of dark communication that we can't see.

It is not quite impossible to eliminate the possibility that there is some sort of dark radiation we could eventually create and detect. There's currently no particular reason to believe such a thing is possible, but it is not currently excluded necessarily. Whatever forces dark matter interacts with could have its own radiation. But it is difficult to imagine in what way this would be superior to EM-based communication, because, again, EM is just so perfect for communication that it's hard to beat.

It's the question people don't want to deal with because they're too busy being "gee whiz golly gosh" about the possibilities... in what way is this other communication method going to be better than EM? Dark matter communication would quite likely look in practice a lot like neutrino communication does today. It's already possible. We know that because we've built it. We don't call it a transmission method, though, because the bandwidth is soooo atrocious that it's reasonably approximated by "0 bits per second", so we just call it a "detector".

We know one way in which it would be superior - very low interaction rates which ordinary matter which would mean much longer propagation ranges.

And their difficultly is a bonus in itself - if you want to hide your communications as much as possible.

Cost is not always the only metric to optimize. Even today, people try to use quantum entanglement to create communication channels where snooping is detectable.

"very low interaction rates which ordinary matter which would mean much longer propagation ranges."

EM already propagates across the known universe.

"And their difficultly is a bonus in itself - if you want to hide your communications as much as possible"

It is unlikely that such hiding is going to be more effective than existing spread-spectrum techniques, which can already put your communication arbitrarily close to the noise floor, and already exist.

Of course, if you're going to leave science behind you're then going to hypothesize what aliens may have done to somehow break through the noise floor so that's not an option, and, well, this is what I mean by pick one; either use science, or imagine whatever you like, but don't mix the two. There's no reason to believe that the noise floor is penetrable and lots of mathematical reasons to believe it very much isn't.

> EM already propagates across the known universe.

I meant it in the sense that EM will be attenuated by gas clouds and solid matter due to the high interaction rate of EM, while neutrino (or presumably dark matter) much less so.

If it doesn't interact with gas clouds how do you build an efficient detector to receive it?

Since we are allowed to step outside the realm of current known physics I imagined what if we could produce a yet discovered energy that could travel faster then light and could also pass through matter. And lets for the sake of this hypothetical discussion say that we could prove there is no possible way to produce this energy without doing it intentionally, ie intelligent life producing it. I also picture this energy interacting only with itself in a way we can detect(it flashes or something). We could build an emitter and watch for the flash. Since it only interacts with itself and only is produced intentionally and not all over the universe occuring naturally we would know we have detected someone else sending the signal.

But then you have the issue that the communication doesn't actually interact with the detector you've built to receive signals.

"I don't think that's dismissable as being a flight of fancy"

What else would a flight of fancy be other than imagining something that we currently have absolutely zero evidence for?

I have no problems with flights of fancy. I like sci-fi quite a bit. I do have a problem with people not realizing they're taking flights of fancy. At the moment, as I said, I am not aware of anything even on the fringes of science that would permit a superior communication technology over EM, and I'm as informed as you can expect a layman to be about the holographic universe idea, violations of the standard model, various dark matter theories, hypotheses about various possible spatial deformations permitted in general relativity that may have started at the big bang, and everything else. There's not a lot of reason to expect something to pop up that's going to be better than light. At best, you could hope to tie it, because it's frankly already nearly perfect, and I wouldn't even hold out a lot of hope for that.

They didn't think particles could be proven as indistinguishable until they realize the laws of physics depend on it and therefore you could test for it.

I don't think it's a comparable flight of fancy to ask about whether there's a way you could detect unaccounted-for energy within some region that isn't one of the usual suspects.

Yes, there's always the "what if our understanding is completely broken", but your comments here feel way too uncharitable and dismissive, willing to equate the two kinds of questions.

"I don't think it's a comparable flight of fancy to ask about whether there's a way you could detect unaccounted-for energy within some region that isn't one of the usual suspects."

I gave you one interpretation of what I mean by flight of fancy already, which doesn't match what you seem to be reading it as.

The problem with the question about where stuff could be hiding is that, as I said, I'm as up-to-date as you can expect to be on this stuff for a layman, and I'm not aware of any "unaccounted for" energy that might be useful for communication. It is not known whether "dark energy" is simply a violation of conservation or if it is perhaps coming from somewhere else, but it doesn't seem useful for communication either way, and I'm not aware of any other places where energy is not accounted for.

Indeed, note all the modern articles are discussing how we are in precisely the opposite situation, and that's the problem for physicists today, that we do seem to have all the energy accounted for and there's nowhere else for physics to be hiding, which is a massive problem because we know we're not done yet.

At the moment, hypotheses about such things would be based on zero evidence. Again, I'm pretty comfortable calling that "flight of fancy". Maybe someday one of them will be correct. But the vast, vast majority of "flights of fancy" are not. Like that stupid "first they laugh at you, then they fight you, then you win" quote that everybody reads as if it's some sort of inevitability. In reality, what happens is that "they laugh at you, end of story" is the dominant case. There is no path of causality where simply because they're laughing at you you're inevitably on the path to winning. The ability to imagine in an incredibly hand-waving way that maybe something exists is not the slightest bit of evidence that it does.

> The problem with the question about where stuff could be hiding is that, as I said, I'm as up-to-date as you can expect to be on this stuff for a layman, and I'm not aware of any "unaccounted for" energy that might be useful for communication.

I'm aware you're not, and explained an example of a non-trivial, responsive answer which would differentiate between the "unknown" and "reasonable to rule out" case. "No, there is a way to measure the total amount of energy flux, across all sources, through a region and it rules out the possibility of undiscovered forms of energy passing through us without us knowing."

Similarly, if someone asked about whether Conservation of Momentum could be wrong, I would point out Noether's Theorem and how it falls out as a result of linear translational invariance of the laws of physics and thus has a higher barrier to disprove and what that would have to look like. I wouldn't just call their question a flight of fancy.

No one deserves ridicule for curiosity or asking which state the science is currently in.

All of your responses just come off to me as attempts to ridicule legitimate questions, so I don't feel comfortable engaging further.

I'm going to take a stab at phrasing the question in terms of a simple yes or no answer. Do you believe it is possible that there exists a physical phenomena that, if described to you right now, would clearly be a "flight of fancy", however would in fact turn out to be real? Note I'm not asking you to state what that phenomena is or to "imagine" anything at all. Just that it can be ruled out that anything is really left to be discovered. Just as though it were the year 1500 and someone described radio waves to you. Because if you say no, that seems awfully confident that science has basically discovered every significant aspect of physical reality, it's just the small details left. The same attutide would have existed hundreds of years ago.

"Do you believe it is possible that there exists a physical phenomena that, if described to you right now, would clearly be a "flight of fancy", however would in fact turn out to be real?"

Yes, of course.

I think those of you who are finding your feathers ruffled need to go back to the initial post. The question is, do you want to answer the question based on current science, or do you want to imagine whatever you want to be the case? Both are valid options. But pick one. You do nobody any favors when you try to blurrily flick back and forth on a whim.

And the truth is, if you are going to just imagine whatever you like, there isn't much interesting to say about it precisely because anything could be true. Could aliens be communicating by getting high on DMT and have found a way to use DMT entities to transmit real, useful messages? Sure, whynot, but what's there to say about that?

By contrast, we can discuss what real science currently has to say about what aliens may be doing. Current science says there's not much reason to expect anything but EM. If you find that unfortunate somehow, that's a psychological thing, not a scientific thing.

Or, at least, we COULD discuss what real science has to say about it if people didn't immediately pop up with the equivalent of "But what about DMT-entity-based communication???!?" every single time.

Good answer, except for the last part. I think there is not much reason to expect we will detect aliens using anything other than EM, because that is all we know. But for all we know they could be sending messages to other galxies by communicating with the outside makers of the AI Elon Musk thinks created the universe.

Your turn: Yes or no, is "communicating with the outside makers of the AI Elon Musk thinks created the universe" something we have zero evidence for? Is that not reasonably categorized as a "flight of fancy"?

If yes, why do you expect to be able to say anything sensible about it? And why are we apparently obligated to discuss it despite explicitly setting up a premise of "let's discuss things using the physics we know?"

This is failing on the most basic level of philosophical discussion here. We are allowed to discuss "If X, then Y" without being obligated to also discuss "if ~X", nor is it a reasonable philosophical objection to "If X, then Y" to say "Well, what if not X?" It is a reasonable objection to disprove X and prove the whole "If X, then Y" conversation is thereby vacuous, but if you can disprove science as it stands today, this is hardly the place to do it.

(I'd also point out I did discuss "what if ~X" even so. It's just that if we're going to assume anything we like, we can get any answer we like. There's a profound sense in which there isn't much to say at that point.)

From Littlewood's Miscellany:

"Schoolmaster: 'Suppose x is the number of sheep in the problem.' Pupil: 'But, Sir, suppose x is not the number of sheep.' (I asked Prof. Wittgenstein was this not a profound philosophical joke, and he said it was.)"

> Your turn: Yes or no, is "communicating with the outside makers of the AI Elon Musk thinks created the universe" something we have zero evidence for? Is that not reasonably categorized as a "flight of fancy"?

absolutely

> If yes, why do you expect to be able to say anything sensible about it?

I said somehting I think was sensible, which is that we have no way of knowing such a thing.

> And why are we apparently obligated to discuss it despite explicitly setting up a premise of "let's discuss things using the physics we know?"

We are not. We are obligated to acknowledge we don't know everything, which you admitted to by stating that sure, something that's a flight of fancy today could someday prove to be true, hence, there are possibly things we don't know. We of course cannot do anything with that, because we have no way to know.

> This is failing on the most basic level of philosophical discussion here. We are allowed to discuss "If X, then Y" without being obligated to also discuss "if ~X", nor is it a reasonable philosophical objection to "If X, then Y" to say "Well, what if not X?" It is a reasonable objection to disprove X and prove the whole "If X, then Y" conversation is thereby vacuous, but if you can disprove science as it stands today, this is hardly the place to do it.

all I wanted to state was that there may be things that prove to be true which if we were to hear them today, we would only be able to conclude they are flights of fancy and nothing more. and we agreed. I'm not attempting to make the "how do you know X doesn't exist?" argument because there's no X that has been suggested except for an intentionally ridiculous example. I'm more making a comment on what seemed to be your absolute certainty that electromagnetic energy is definitely the only way any intelligent life form would ever communicate across distances, science has successfully and provably ruled out any other possibility.

> What else would a flight of fancy be other than imagining something that we currently have absolutely zero evidence for?

It would be a flight of fancy to argue for or imagine a specific one, but it's not a flight of fancy to say, "hey, there's probably forces and particles out there we don't know about or understand yet". Hell, it would be obscenely arrogant not to acknowledge that.

>What else would a flight of fancy be other than imagining something that we currently have absolutely zero evidence for?

Exactly, but that was spirit of OP's question.

I do think that the fact that we can rewind our own history and find examples of technologies that were unimaginable at some more distant point in our history as something more than "absolutely no evidence."

> I am not aware of anything even on the fringes of science that would permit a superior communication technology over EM

In another comment you mentioned things such as gravity waves, neutrinos, etc. You also mentioned that these things are far more expensive to generate than EM. I think those particular facts are "engineering problems to be solved" rather than just fundamental laws, yea? I never fired off a neutrino, I know you need a sun or a particle accelerator to do it, so I get why it's considered expensive, but is that inherent?

Even with EM, they could have a highly advanced encoding format which is barely detectable about the random noise floor (spread spectrum like). US army uses these kind of techniques to make the signal both hard to detect and hard to jam.

Who knows how far you can push this, maybe to the point where it's essentially impossible to detect the signal if you are not the intended target.

Most signals would presumably also be highly targeted. The narrower the beam you are sending, the less energy is required to send the information. Unless aliens cheap out on antennas or prefer to waste lots of energy on broadcasting in all directions, we are very unlikely to be in the path of their communication beams.

I thought we could Van Eck phreak the aliens.

Makes you wonder what they call Van Eck phreaking.

Gardan's Steelyard?

No wait, that's something else.

clearly Saunt Eck's inverted speely.

Wouldnt heavily advanced civilization wanted to remain silent? If they know they are less sophisticated aliens out there like us humans, then for sure there are civilizations more advance than they are. I suspect they are not interested of sending their own signal to someone who could anihilate them with a push of a button (even higher civ.)

The only civilizations we have known definitely show that contact involving a great technological difference is usually a disaster for the less advanced people. https://en.wikipedia.org/wiki/Fermi_paradox#It_is_dangerous_...

The Dark Forest (Three Body Problem) explores this

Via video game, no less. Well, simulation-y video game. Sort of.

Scarcity is an important factor. Today, primitive societies (mostly) safe from Western conquest because they simply don't have anything we want.

That's more about selection bias than about anything that's inherently different about advanced societies today. There were primitive societies that did have valuable things [1], and they were all destroyed or conquered very soon after contact with more powerful societies, and they remain vulnerable to outsiders as soon as they come into possession of something of value. When gold was discovered on the land of uncontacted Amazonian tribes, for example, this happened: https://www.theguardian.com/global-development/2018/aug/22/a...

This is a pretty essential point that I think changes the calculus of contact quite a bit. A civilisation capable of visiting us at a reasonable expense to themselves would presumably have much easier access to near unlimited astroids/moons for automated mining.

So unless they really prize rare meat or have other illogical goals you wouldn't expect any aliens to visit us until its as easy for them as it is for us to take a transatlantic flight... I wonder if they're also arguing that they should stay silent to preserve our culture instead of curing our diseases etc.

In Carl Sagan's Contact (the book, not the very good movie), Ellie is on the life-extension station with SR Hadden and about to land back on earth after the accident. I can't find the exact quoted exchange but it goes something like:

Hadden: Ellie, when you find them and talk to them, be VERY careful. These folks are old and their tolerances for risk may be alien to us.

Ellie: Well they sent us the Message, they obviously want to chat

Hadden: With beings that may be immortal or close to it, what we may consider a sure-fire bet may seem like an impossible risk to them. When they offer you something, you take it, you hear?

If someone can find the actual quote, thank you!

The closest approximation I can find is pp. 292--293. (I don't have a copy and haven't read it in about twenty years, so there may be a better approximation available.)

Hadden and Ellie have a brief discussion about the potential to market dying in space as a "really nifty last indulgence", whereupon Hadden segues to the topic of immortality and says the following:

"Now, I'm not bringing this up so I can boast. I'm bringing it up for a practical reason. If we're figuring out ways to extend our lifespans, think of what those creatures on Vega must have done. They probably are immortal, or close enough. I'm a practical person, and I've thought a lot now about immortality. I've probably thought longer and more seriously about it than anyone else. And I can tell you one thing for sure about immortals: They're very careful. They don't leave things up to chance. They've invested too much effort in becoming immortal. I don't know what they look like, I don't know what they want from you, but if you ever get to see them, this is the only piece of practical advice I have for you: Something you think is dead cinch safe, they'll consider an unacceptable risk. If there's any negotiating you get to do up there, don't forget what I'm telling you."

(Please forgive transcription errors.)

https://books.google.com/books?id=Q6o51-W_z8MC&lpg=PP1&dq=sa...

Perfect! Yes, this is the passage I was thinking of. Thank you!!!

Energy is very abundant by E = mc^2, so what we consider "wasting energy" they may not even consider.

The average web page is bigger than the original DOOM download, about 2/3 the size of War and Peace. In an era before Gutenberg, when monks copied books my hand, I wonder if anybody mused that nobody would "waste" the equivalent of 750 pages to communicate "please log in using your email and password."

You need to consider that you're sending a message over millions of light years. You'd need a a power output comparable to a star to be visible across that distance if you didn't focus your message (because, obviously, stars themselves do it!)

If you want to do it you might as well use the star itself it won’t be that hard to encode a message into the light emanating from the star itself you only need a sufficiently large polarizer or anything else capable of modulating the light coming form the star.

Any civilization that would need to communicate even across a few 100 light years would be capable of doing so.

I’m totally ignorant in this so my question could be half baked but what exactly are you saying?

By polarizing light, do you mean that a device would intercept the photons escaping from the sun and then changing their wavelength to encode a message similar to Morse code?

Or do you mean something else entirely?

Edit: a word

A polarizer only allows light of certain polarity (the "direction" the waveform oscillates, think sunglasses or 3D glasses, or the polariser in your LCD screen) to pass through.

https://en.wikipedia.org/wiki/Polarization_(waves)

But it doesn't have to be polarization just any easy modulation of the light, polarization is just easy to do since all you need is a huge polarizer and a few reaction wheels.

Think about planetary transitions; we can detect those quite easily this is how we find exoplanets these days, in fact we can fairly accurately identify the composition of the planet's atmosphere and the atmosphere is a fairly thin slice of the entire planet's silhouette.

So the only thing you need to do is to position a sufficiently big object it doesn't have to be even that big (still huge in our scale but something in the range of 100's or even 1000's of kilometers across would likely be sufficient the radius of the earth is only 6300KM~ and we can detect planets smaller than the earth AFAIK, and it can be as thin as a solar sail and considering we already build satellites with antenna that unfold to the size of a few football fields it might be possible even with our current level of technology or something not that far off) because you take advantage of the distance between planetary systems that object needs to be able to modulate the light it can be polarization, abstraction, color filtering.

To put it simply make a huge ass thin TFT LCD let the sun act as a backlight and put it in a stelar synchronous orbit from the vantage point of the star system you want to communicate with so it would always appear in line between it and your local star and blink your messages away.

If you want to go for the golden star then build a huge ring which also is capable of acting like lense this can allow you to have a communication array which can also direct the signal in a relative narrow beam.

Thank you for that reply. Makes a lot of sense.

It doesn't even have to be that huge if it's further away from the star.

Then you’re back into having a narrow transmission beam

A polariser filters light whose electric field is oriented in a particular direction.

Like modern 3D glasses.

> intercept the protons escaping from the sun

Minor typo: you mean "photons".

Thanks. Corrected.

Solar wind too though.

If you haven’t read Liu Cixin’s Rememberance of Earth’s Past trilogy you might really enjoy it.

That's an interesting idea (and something touched on in The Dark Forest[1], which is pretty good just for a peek into hard sci-fi through the lens of another culture).

How large an area would you need to cover to accuratly dim a star's output to an array at another star, say 100 light years away, if you positioned yourself towards the edge of the solar system? Is this cost effective, or any faster than using targeted EM?

1: https://en.wikipedia.org/wiki/The_Dark_Forest

>How large an area would you need to cover to accuratly dim a star's output to an array at another star, say 100 light years away

Jupiter-sized is good enough for some 3700 light-years with 2016-era technology [1]. We know because that's one of the current methods of detecting exoplanets [2].

[1] http://www.sci-news.com/astronomy/kepler-1647b-circumbinary-...

[2] https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanet...

On the other hand Kepler 37b is only slightly bigger than the moon and its 200 l/y away.

Planetary transistion detection isn’t just a question of size (of both the star and the planet) and it’s orbit but also of alignment of the orbit of the planet, the orbit of earth and the two systems.

Now with a predetermined communication array the alignment isn’t a problem more so you can use a light shield at the receptor similar to StarShade which will be used to block the light from the star allowing Kepler to image the planets directly to block the majority of the light from the star which would reduce the required size of your transmitter further.

It’s quite likely that over a distance of even a few 100 light years with a modulator as small as a few 100 km across might be sufficient.

The problem with communicating across even a few hundred light years is that everybody's bored and gone to do something else before the response arrives.

You'd need a spectacularly static civilisation to engage in any meaningful communication over the timespans involved.

That's a very young-civilization perspective. 100 years seems like a long time to us because it's approximately 1% of the age of our civilization. But it's possible that civilizations that are hundreds of millions of years old exist. To such civilizations 100 years would be a flash in the pan.

Also keep in mind than until recently on earth we used transmission mechanisms for long-on-earth distances that were closer to the order of magnitude of 100-year transmission time (a few months) than to present transmission time (a few milliseconds).

>But it's possible that civilizations that are hundreds of millions of years old exist. To such civilizations 100 years would be a flash in the pan.

I don't know if it is possible for a civilization to connect the past to the present over such long periods of time. The individuals in each generation would have to pick up, use and pass on all the information that came before.

Our capacity to take past information into account, individually and collectively, is very limited, even if it gets stored somewhere. We can see that in many debates on here where arguments of the past are repeated many times over without younger participants having any awareness of what's been said before.

We can compensate for that to some degree by continuously retelling old stories. But relearning old stuff necessarily competes with new information for our limited mental capacity and so old information inevitable degrades over time.

Even religions, where there is a strong emotional incentive to retell old stories, are struggling mightily with even understanding what the original authors meant by the words they used and how to apply any of it to the current situation.

I think for a civilization to retain its collective memory over much longer periods of time requires completely different individuals. It requires individuals that are able to grow their mental capacity at the same pace as the amount of accumulated information grows.

If you consider the combinatoric explosion, this is unimaginable in a biological organism based on evolution and ultimately even in an AI.

I also want to add that age-wise we might be pretty old. Our galaxy (13B) solar system (5B), our planet(4.5B)are pretty old considering the Big Bang happened 14B year ago.

Definitely in civilization time that leaves a lot of room for a few milion years here and there, but still, we could be the oldest and most advanced (at the same time I do hope there is a civilization out there less eccentric and egocentric as ours...)

100 years doesn't seem like a long time to me because of the age of our civilisation or species, it seems like a long time to me because of the lifespan of our species. I certainly can't communicate at all on a 200 year RTT, as I'll be dead and forgotten before I get an answer.

If it's communication, that implies a two-way exchange of ideas. The galactic equivalent of blogging would be like all such communications: typically of more interest to the sender than the receiver.

If we assume a long-lived species that can receive a response within its lifetime, we must also assume that during the intervening time little enough of the context has changed that the answer is still relevant. That means a species and a civilisation that has extremely little change over hundreds of years.

This is what I mean by an extraordinarily static civilisation.

(But if it's so static, what could possibly be said that has material bearing on anything? :-)

Maybe not bidirectional communication per se, but it’d still be pretty valuable to receive a live feed of what the other civilization was up to hundreds of years ago. Especially for things like scientific advances and important works of literature – but I suspect people would also be interested in the day-to-day trivia. I mean, as an individual I’m already largely powerless to influence any of the events I read about in the newspaper, but I still read the newspaper.

Besides, if you’re an AI or an uploaded brain, you can send yourself over a communications link. That’s pretty valuable, regardless of whether you ever intend to return!

This reminds of the time I first visited US. As an Indian, the first world infrastructure and living standards had me in awe.

After going back to India, merely showing things to people on Google Maps was an experience of its own.

People went like: Do people in other countries, live that well?

I'd fathom when we see some advanced civilization we would probably react the same way.

How much do you pay attention to the live feed of news from Mauritius? (If you live anywhere close to that country, or have ties there pick a different country on a different continent). Somewhere in my family history is the towns where my family immigrated to the US from, but I don't care at all about news from those towns.

The news in my town is of interest to me, nobody else would care about the latest live music at the local stage.

Science might be of interest, but the problem is both cultures will work in parallel, so we can assume that majority of advances one planet discovers are discovered by the other planet in the mean time.

The nearest star (which might not even have a habitable planet) to earth is too far away for science collaboration other than the "here is new type of signal we are sending your way, see if you get it", and even then you take the risk that the other planet chooses to not listen for whatever reason (it wouldn't surprise me if some theory require this level of cooperation). It is close enough that some "we are studying this lead, so you probably want to look at something different to avoid duplicate work".

As we get farther and farther from the other planet collaboration is less and less useful. You quickly reach a point where the planets can advance faster by duplicating effort than talking to each other (other than as a much latter verification of current theories)

Of course if we colonize a planet 100 light years away you can assume a few hundred years of the colonists working hard to establish the colony and so getting science and technology feeds from Earth will be useful since then they can make a copy of widgets without having to design it from scratch. Eventually they will get established and start producing their own science locally, and soon the feed will be useless and not of interest.

If I were an AI or uploaded brain, I'd copy myself over the communications link, fully expecting to diverge into two distinct individuals.

That is the first time I've ever thought about that particular obstacle to EM technologies as a means of hyper-distant, bidirectional, purposiveful communication between advanced civilizations. I've always thought of EM (Radio/Communication Technologies) as potential tools to confirm specific sources/locations of other intelligent life as well as possibly their purported agenda/intention/lifestyle/threat-level? (or level of intelligence and even to develop [flawed but useful, a.i. based] predictive algorithms of their future likelihood of physical contact/threat and/or their rate of scientific advancement, based on analysis of numerous factors including their encoding used, past broadcasts compared to current, means of broadcast, etc. Etc. Etcetera.) [STRICTLY LIMITED TO/AT the time of the broadcasts, not at the time we receive them... BIG DIFFERENCE IN ASSUMING THAT THE TWO ARE THE STILL THE SAME!]. Never in my wildest dreams, would I consider us as humans advanced enough to ACTUALLY RESPOND (IN WAY THAT WAS COMPLETELY SAFE, FORETHOUGHT, LOGICAL, CALCULATED, MORAL, AND MUTUALLY-BENEFICIAL!). We shouldn't knowingly, directly communicate or reply to forces beyond our wildest comprehension, for what we wish to be a dream for the future of mankind could quickly turn to its worst nightmare, if we are not careful, moral, loving, prudent, and conscientious. We should not have the audacity to treat our supposed Galactic neighbor(s) based on behavioral assumations, if we ever resort to treating them any way whatsoever, which until we reach a far greater point of advancement (both materially, defensively, socially, scientifically, technologically, and, in all honestly, Spirtually) I advise against, 100% completely. Just my take. Learn what we can without exposing ourselves.

Seems to me that the size of the star would be a problem. Assuming the process of actually building stuff large enough to cover a star is solved, how do you control the polarizer to get any reasonable bandwidth? The light emitted from one side of the star will be shifted in time relative to the light emitted from the other side, in anything other than a very narrow beam. Targets outside of this beam will not really receive much of a signal due to interference.

The diameter of Sun is 4.5 light-seconds. This is the lower bound for Sun-sized polarizer switching, as whatever switching process is it has to propagate at below speed of light. Which gives a really poor communication bandwidth even compared to a human Morse operator.

Radio is much better bet.

Never underestimate the bandwidth of a truckload of hard disks.

Latency hardly matters when the majority of the lag is the 100 light year leg: you first spread out your whole message to the surface of the filter with a high bandwidth distribution medium. Then each section of the filter switches in sync, encoding the message without relying on a real-time input from a central location light seconds away

what you are saying could also be: other civilizations would do the same as we do. send small unmanned drones into space, and not just signals. they are much slower, but allow much more information and better reaction time, if the onboard logic does that. and they are not mistaken for something else, as in this case.

Is it necessary to use the star one is orbiting around?

Why not use an array of smaller polarizers that can be modulated when they block the path of a bright but less adjacent star’s light to the recipient?

Can't you delay the signal sent to the center-parts of the polarizer relative to the edge? I think the panel would appear to switch all at once to somebody far away. Seems like this would increase the bandwidth.

Problem is, a star is curved, with the limb being over two light-seconds farther away from an observer than the center. Sure, you can switch the whole surface of the star as fast as you like, with bandwidth limited by how accurately you can synchronize the switching components. An advanced civilization might be pretty good with attosecond-level stuff, but the signal gets spread out over seconds regardless of the synchronization superscience you apply.

You can phase the switches and "aim" the star's signal at a point in the sky. Lower-frequency modulation can get signals to observers not on the direct line, at a lower bandwidth, and you can probably sweep these. Worst case you can blink the whole affair slowly; a star with a five second light curve is going to be pretty interesting.

You don't need to place the polariser right next to the sun; you can use a smaller disc to modulate it's output in one direction.

Like the way the earth is large enough to block the sun on the entire moon during a lunar eclipse.

If your shield is smaller than the star's diameter, you have a penumbra effect. Rather than stellar occlusion, at a sufficient distance you have a stellar transit.

Building a static support for your polariser might also prove challenging.

Ah, yes of course. Though if your disc is large enough, such a transit should still be detectable.

You're trying to detect the modulation, not merely the transit.

Your noise floor is now vastly greater.

They could be basically the same - during each transit you could either let the light through or block it.

Now you've decreased bandwidth to orbital period.

I missed the part about some minimum speed, but it's still flexible in regards to how many levels or frames per transit you use. The point is really to be able to communicate at all - without using a star's light it's basically impossible after a certain distance.

There is that "something is better than nothing" element.

I've also been thinking of whether or not some sort of stellar laser or maser might be possible. Modulating a narrow, tightly focused beam.

It would take 2.25 seconds for a clock signal to propagate throughout the polarizer, but, after that, all distinct elements could sync up for whoever is perpendicular to the transmitter and blast away at whatever bandwidth the signal transitions allow.

And I just imagined an Elsevier-like alien company controlling the broadcast bitstream for an entire star.

"...mit $700 trillion to renew your subscription to PubStar. Sol System, please remit $700 trillion to renew your subscription to PubStar. Sol System, please remit $700 trillion to renew your subscription to PubStar. Sol Sys..."

I had this rough question (i.e., while entertaining causes as elaborate as a Dyson sphere, considering that a star might intentionally be used to send a low-information rotating signal like a lighthouse or signal/Morse lamp out along a plane) after the news about Tabby's star broke. I.e., I emailed it to Tabetha (no response; didn't expect one).

This is precisely why using neutrinos would be an attractive idea - the signal could travel over extremely long distances with very little diffusion/attenuation. (I.e., as long as you have a narrowly focused beam, to control dispersal, the beam itself won't be weakened by any intervening debris.)

> Energy is very abundant by E = mc^2

While we can expect a sufficiently advanced civilization to be in control of vast sources of energy, we need to consider losses, because nothing can be 100% energy-efficient. If sending data to the next node of your intergalacticnet requires you to deal with a Hiroshima per second of waste heat, yours is not a particularly attractive communication channel.

And, unless you have a very large heat exchanger, you are vulnerable to side-channel attacks where a third party can detect the heat you need to dissipate.

Perhaps instead of waste they are worried about, it's detection. Instead of broadcasting everywhere and letting all the swarm devouring aliens know where you are, doing a highly focused beam is far less likely to get detected.

Surely any species that manages interstellar travel will have a much easier time growing sentient beings to eat on their own planet(s), rather than going to other solar systems, lifting the people there out of their gravity well into space, and consuming them?

Something like FHSS (https://en.wikipedia.org/wiki/Frequency-hopping_spread_spect...), not only a low level of signal is spread throughout a board frequency range, the central frequency is also changing many times per seconds, synchronization and decoding is only possible if the CSPRNG key is known. The signal of interplanetary communication is also highly directional.

I guess an alien civilization has much better ideas to avoid detection.

There's a difference between successful real-time decoding, and just determining from a full-spectrum recording whether it is the case that a signal exists, even if its behavior is unpredictable.

The point of spread-spectrum signal is that it's indistinguishable from noise unless you know the key.

With frequency-hopping you still have spikes in the spectrum around the frequencies you hop between, but with most modern systems you no longer have anything distinctive to find.

It's not indistinguishable from noise, if it is powerful enough to be received at all. If you filter based on the background noise threshold, you will discover a signal that quickly jumps frequencies in a pattern that is unpredictable without knowing the secret key. If frequency hopping is all that is used, you could even recombine the pieces to put the original message back together again. But in any case it will be very plainly obvious that the signal exists. A radio with a hardware limitation of only tuning to a specific frequency at a time would be unable to pick up on it, and would only hear transient blips as the signal enters and leaves the channel, which is what people mean when they say spread spectrum "looks like noise".

You could defeat this analysis by actually broadcasting noise on all frequencies, so the transmission frequency is indistinguishable, assuming the encryption used is also indistinguishable from a random oracle. But now you have a noisy point source in the sky, even if you can't decipher the contents of the message.

Succinctly put, obfuscation techniques like frequency hopping spread spectrum are tactical techniques that try to hide transmissions from actual radios in widespread use, not hide the existence of the radio signal in some physical sense. FHSS radio transmissions look like noise sources, not silence. Which is basically what SETI is looking for -- sources of radio noise unexplained by our understanding of astronomy.

It is possible for the signal to be below the background noise. For example, GPS works this way. Sonars on submarines do the same thing, they send out a noise-like signal that can be detected only if you know what to correlate it with. There's always some noise to hide the signal in.

This isn’t true. If the signal was below the noise threshold, and no mechanism provided for detecting noise separately (as twisted pair provides, for example) it would be literally impossible to separate signal from noise. That’s what the noise threshold means.

GPS is not below the level of background noise. Not is sonar.

what if there exist ultimate limit to knowledge itself and laws of universe that can be discovered? it would imply that any civilization that reaches that point will have nothing to gain from communication with other civilizations.

How would you know that you have reached the limit of knowledge?

You probably wouldn't be able to for sure but if you had no more unexplained phenomena around then you'd probably have a reasonable idea.

Of course that only applies to the laws of physics. You'd still have an effectively infinite universe of maths, geography, biology, etc. to explore.

You would still not know. Maybe there is a branch of physics that you're simply biologically not equipped to even perceive, comprehend or understand in the slightest. Maybe not. The point is that you can't know. Not too long back, people thought gravity as entirely newtonian and couldn't imagine that gravity could behave like waves. Or that particles can exist as both particle and wave.

IMO the limit of knowledge is simply the limit of information you can cram into a region of space without it collapsing into a blackhole because of that.

No matter how hard you try, you cannot teach a mouse to learn french. That is why.

That's more a reason why knowledge is unlimited; a mouse is incapable of understanding french, but knowledge of french does and can exist, so the mouse doesn't know everything. There is a biological but not inherent limit.

There's also the possibility that some ET's may want to be known, and are sending out an easily-detected beacon.

That might be our best hope.

Yeah, who in his right mind would broadcast his position to all the possibly much more advanced, resource-hungry and expansive species out there? ;-)

Perhaps someone with a very strong conviction that they are already the most advanced, resource-hungry, and expansive species out there ;)

The Borg have become lazy indeed.

I would make all my planet's tech based off of sewage.

Borg Drone 8 of 200: "Nothing to Assimilate here...time to go assimilate Risa".

But how do we know our concept of an easily detected signal isn't merely a product of how our technology evolved?

I think it's worth investigating and looking for signals because it does find interesting phenomenon, I'm just very skeptical we'll ever find intelligent life doing so.

> how do we know our concept of an easily detected signal isn't merely a product of how our technology evolved?

Because 150 years of investigation very very very strongly implies that electromagnetism is one of the most powerful of a very short list of fundamental forces.

I have a half-baked idea that some alien planet's marketing team is probably using pulsars as an advertising stunt. "Relax on Risa" and the like. I don't know how one would go about modulating a pulsar's output, but pulsars are seen everywhere.

Sounds like a trap...

Maybe a modified star lifting process could work to change the pulsars pulse rate? https://en.wikipedia.org/wiki/Star_lifting

Even then you have to ask "How long do ETs live?"

Listening for radio signals is way, way cheaper than broadcasting. It might be fair for an advanced civilization to fire up its transmitter for one year every thousand, and transmit a dense "welcome to the universe, here are our civilization's greatest achievements" message to all the listening civilizations. Running a listen-to-the-sky antenna for 500 years is still vastly cheaper and easier than what the advanced civilization has to do to transmit the message, and transmitting constantly is kinda hella wasteful.

That's a very good point. When we first started listening for alien signals, we assumed that of course aliens would have TV and radio. In the few decades since then we have mostly switched to digital TV which has much more efficient (looks more like noise) encoding, and a trend of moving away from broadcast to YouTube, Netflix and podcasts is also evident (using both higher efficiency encoding and much lower transmit powers). And developments like 5G are intended to accelerate this development by using even higher coding efficiencies and shorter distances/lower power, as well as beam steering to directly target the receiver. Perhaps civilisations only typically use broadcast communications for <100 years, a mere blip at galactic scales.

Wait, why is Quantum Entanglement a non-starter? How does that require a conventional channel? Once you have the two entangled, assuming you have some way to change the state of one with out breaking the entanglement, then how is that not enough for communication?

Because once the particles are entangled, one has to be moved by conventional means to the destination while the other stays behind.

Sure, but you could still create a two way walkie talkie that couldn't be eavesdropped on and would allow faster than light communication this way, theoretically.

You can make it secure from mitm with this but it doesn't allow ftl. You can't use the entangled particles themselves to do the communication since you cant control how the superposition collapses when you measure it. This allows you to get two streams that nobody but you and the party knows but they're fundamentally random and unpredictable, you can't encoded information into it, just use it as a one time pad essentially.

But that in itself is a signal, right?

Say you have two sets of two entangled particles, all four particles in similar states. You have one particle from each set, your partner has the corresponding particles in the sets.

You check both particles you have, and:

- if both particles have similar state, then your partner hasn't checked any of their particle states, because neither have collapsed.

- if one particle has collapsed and is in a different state than the other particle, then you know your partner has at least checked the state of one of particle sets, possibly both.

If you partner is 50 light years away and checks it only seconds prior to your check, then they are signalling you at faster-than-light travel, right?

But you have to communicate the states of each other's particles (as far as you can tell random noise) to compare/contrast and glean influence, so it's only suitable for encryption of classically transmitted messages.

Think faster-than-light XOR ;)

Got it, so the state is random for all particles until it is measured by your or your partner, afterwhich the other particle state is known. But the act of measuring or the decaying doesn't tell you when (or if) they measured it because the state never changes, it just becomes known.

It's not random; it's a superposition.

It is perhaps less nonsensical (in a "common sense" way) to think of it in terms of the many-worlds interpretation. The moment you have created the photons, you have forked the universe - but observers on both sides are still identical in both worlds, because they haven't done anything that'd allow them to figure out which universe they're in. So for each observer, we treat both "versions" of that observer as one and the same.

Now, when one of the observers measures their photon, they figure out which fork they're in. And then in that universe, the other observer measuring it will also get the same result, of course, proving that they're also in that same universe. And in the other universe, the second observer will get the opposite result, again, proving that they're in that other universe. But neither measurement actually caused anything to happen, nor did they get any information about the opposite observer in their universe as a result of it.

abdullahkhalids has the correct answer. Even if you have the entangled particles already in place, you can't communicate with them.

The real proof is that if you could, we'd already have this technology and high-speed traders would already be using it. If it could exist, we have all the tools to build it; it's far simpler than even a 4-qubit quantum computer, which we've also built. We don't have it because entanglement can't be used that way.

Nope, you couldn't. From all the experiments and theory we have on entanglement, you can't use it to communicate faster than light.

Which is still extremely useful for things like probes.

Instant comm's to Mars rover or even voyager.

Of course no ones figured out how to make use of entanglement for information transfer.

Pops up a lot in Sci-Fi, reading Three-Bodied Problem now and the aliens sent "sophons" basically probes the size of protons at near the speed of light to earth from Alpha Centauri, they arrived in a few years while their invasion fleet will take 400 years to get here. The sophons spy and interfere with earth communicating with aliens via quantum entanglement.

> Of course no ones figured out how to make use of entanglement for information transfer.

Saying "no one's figured it out" is misleading because it creates the impression that it's an engineering problem to be solved.

According to our best understanding of quantum mechanics, the laws of physics fundamentally do not permit faster-than-light communication, whether through entanglement or any other mechanism.

Well, of course they don't. How would you even begin to build a simulator for something like that?

Communications overhead between the nodes is bad enough as it is.

I was trying to imply that its probably the best avenue for research, and also we may never figure it out, might be a dead end.

However I would say the reason it is used so much in sci-fi is it currently the one way we can cause action at a distance faster than light, which is so tantalizingly close to communication.

I wouldn't say we're close to FTL transfer of information in any meaningful way. In particular,

> we can cause action at a distance

is not true, either.

>is not true, either.

I didn't think this was settled and depends on your interpretation of QM: https://en.wikipedia.org/wiki/Action_at_a_distance

…and on your precise definition of "action and a distance", yes.

But there is something like standard textbook quantum mechanics which most physicists subscribe to, i.e. the Copenhagen interpretation, and while I'm not saying this is the interpretation everyone should follow and believe in (in fact, there are good reasons to be dissatisfied with this interpretation), the term "action at a distance" was coined in the context of the Copenhagen interpretation, so I think should therefore also be interpreted in this context.

Now, Copenhagen is a local and non-realist theory, the latter of which meaning among other things that the wave function is not believed to be an object of reality. Therefore, in this interpretation, the collapse of the wave function is merely a tool for predicting the outcome of a measurement and not something that's believed to actually happen. The same thing goes for an "instantaneous collapse" at a distance — this action does not exist in reality.

I know there is probably going to be someone who objects to me saying that Copenhagen is non-realist and local. But those people will have to explain to me how they would bring the actual existence of the wave function and its collapse into agreement with relativity and, in particular, with different observers who come to different conclusions about when the wave function collapses. For instance, for one observer, it might be Alice who causes the wave function to collapse and, thus, Bob to measure a certain outcome but then there is always going to be another observer who will say the exact opposite, namely that Bob caused the collapse. So, essentially, if you really think the wave function is an object of reality, all hell breaks lose.

Needless to say, even if you completely disregard these issues and still want to think of Copenhagen as a realist but then necessarily non-local theory (in which case I'd say you should really give your theory a different name), this is all just splitting hairs because the only thing that matters is that there's no FTL transfer of information. This is the only experimentally verifiable statement we can make.

There is no reason to think quantum entanglement could be used for FTL communication. The theory which gives us entanglement also proves (mathematically) it can't be used for communication.

Our understanding of the model is thought to be quite poor. Further, we should not ever mistake the model for reality or attempt to fit data to predictions. The cosmos might not be anthropomorphic.

The no communication theorem is not the no communication hypothesis, it's actually a math proof. You start from the principles of quantum mechanics (unitarity, etc), define what you mean by entanglement (non-factoring states), and prove it's not possible to use those states to win the communication game. This is an aspect of quantum mechanics that we understand extremely well.

You still need to transfer a message using a classical channel to actually communicate anything. Remember, there is no known way to communicate faster-than-light.

https://en.wikipedia.org/wiki/No-communication_theorem

Following this rabbithole lead me here, which explained it in a way that made sense to me: https://www.lesswrong.com/posts/DY9h6zxq6EMHrkkxE/spooky-act...

Just in case anyone else is struggling with this, as I was :)

Good article! This part makes me laugh though

>Here's something that, as a kid, I couldn't get anyone to explain to me: "Why can't you signal using an entangled pair of photons that both start out polarized up-down? By measuring A in a diagonal basis, you destroy the up-down polarization of both photons. Then by measuring B in the up-down/left-right basis, you can with 50% probability detect the fact that a measurement has taken place, if B turns out to be left-right polarized."

He must have been a pretty smart kid...

The way I understand it is that you still need a CLK signal, entanglement is the DATA pin. The primary purpose of entanglement is privacy. A sufficiently advanced species may choose to use entanglement to hide from the rest of the galaxy, and the CLK radio burst could be made to look suspiciously like natural phenomena (FRBs).

However, a major point of contention is that humanity occurs far too soon in the life of the universe. It has taken life on Earth 3.5 billion years to evolve to us, that means that there have been just under 4 epochs of human evolutions in the age of the universe (and just over 1 epochs of human evolutions in the age of Earth). Chances are, using sci-fi nomenclature, that we are the "ancients." We have quite a lot to get done for those that follow.

Geeze that's a lot of words to explain something so simple.

Lets say you use pure energy to create a particles with a non zero spin (substitute a charge if spin is confusing) that immediately separate from each other at high speed. The rules of the universe demand that the sum of the spins (or charges) equals 0: eg if one is an electron the other must be a positron. So now you have two particles flying towards you and me, but no one in the universe knows which is which except possibly the particles themselves, so we say they are entangled. If I look at the particle coming towards me I have no way of knowing if I will see a positron or a electron. When I do look, I know what you will see if you look. Which is nice, but no information has passed from me to you. Instead have both learnt something new. The definition of communication is you pass some knowledge you knew before the process started onto me. (In fact we learnt the same thing.)

The word entanglement seems to imply if one particle changes the other undergoes a corresponding change. Whether that's true or not is a bit of a mystery. In any case it doesn't matter how it happens. Even if there was a "global variable" and even if it suddenly changed value when one of us observed it, merely observing it destroys the entanglement. So yes we both learnt something new and maybe it was communicated faster than the speed of light, but we now know the first observation doesn't communicate any information we knew before. And because observing it destroyed the entanglement no new information can be transmitted.

First, you have to transport one of the entangled pair to your remote location.

> assuming you have some way to change the state of one with out breaking the entanglement

Second, this isn't possible.

When you measure the entangled pair, you know they'll be correlated: if one is A, the other is B, and vice versa. But when you measure one of the particles, you have no idea if you're going to get A or B. You don't have a way to force the entanglement to go a direction you want. So it doesn't serve as a communication channel.

> assuming you have some way to change the state of one with out breaking the entanglement,

This isn't possible. Not only is it quantum mechanically impossible to change the state of one without breaking the entanglement, it is quantum mechanically impossible to observe the state of one of them without breaking the entanglement. Remember that in quantum mechanics "interacting," "changing the state," and "observing" are all the same thing.

Can you know whether or not a particle is currently entangled? With observation of only 1 of the entangled particles?

Say you had millions of entangled particles, you ship their companions to the other end of the galaxy. You now have a million bit array to encode data into for 1 time use?

I’m guessing you can’t know whether a partical is currently in a state of entanglement...

EDIT: my question has already be asked & answered several times...one such example: https://physics.stackexchange.com/questions/207169/can-i-tel...

> electromagnetic radiation basically has every characteristic you're looking for in a communications medium

Communication by electromagnetic radiation suffers from the fact that the radiation diffuses indiscriminately in all directions. Consider two models of "communication" -- in model 1, messages are sent by lighting a lantern and waiting for the other party to see it, and in model 2, messages are sent by propelling a less wave-like rock into the other party.

Model 1 is faster. But in model 2, my messages don't get broadcast to the entire world as I send them, all the energy I put into sending the message goes into delivering it (whereas most of the energy given off by the lantern is wasted), and if I start throwing rocks at my friend, that will not in general interfere with the rocks thrown between you and your friend.

"Communication by electromagnetic radiation suffers from the fact that the radiation diffuses indiscriminately in all directions."

While lasers technically do not need to be beam-like, I would point out that beam lasers do exist, as well as many other directional effects, as seen in flashlights and such.

It is a bizarre alien race that people are hypothesizing that apparently uses whatzamamagic communication that we currently can't even conceive of, but aren't capable of building the things we already know how to build that can provide very good directionality today. A very particular sort of powerful.

Beam lasers exist and stay narrow on the scale that we use them. They are tighter flashlights. Turn on any flashlight and the rapid diffusion of its light will be extremely apparent.

And I'll note that I responded to the comment "electromagnetic radiation basically has every characteristic you're looking for in a communications medium", with no mention of aliens at all. It is not true that electromagnetic radiation basically has every characteristic you're looking for in a communications medium.

There is a fundamental difference between a laser and a concentrated flashlight–lasers are coherent while ordinary light is not and cannot be made so no matter how much you focus it.

Lasers still diffuse; they are not fundamentally different in that sense. In the signaling sense of "is the light there or not?", whether it is coherent, or would be coherent if it was there, is not relevant to anything.

Lasers don't technically "diffuse", they spread out due to diffraction inside the beam itself. So they are much, much easier to better to in a reasonably directed beam.

Other than stars etc., I don’t think know any genuinely omnidirectional light sources. Even other substellar objects emit non-isotropically because they aren’t spherically symmetric. And at most frequencies, light doesn’t diffuse much.

To put it another way: lasers, lenses, parabolic dishes.

> Other than stars etc., I don’t think know any genuinely omnidirectional light sources. Even other substellar objects emit non-isotropically because they aren’t spherically symmetric. And at most frequencies, light doesn’t diffuse much.

In what cases does it matter that stars are not symmetrical enough to emanate light omnidirectionally? Stars are pretty close to isotropic.

That’s my point. They — stars and some stellar remants — are basically the only thing which are isotropic. Everything else is directed, has some gain over isotropic in the peak direction/s.

I don't know if I'd describe the speed of light as "low", more like the universe is really, really big

You don't sound like you do a lot of distributed/network programming. The speed of light is achingly, infuriatingly slow.

Things would be a lot simpler if it were faster though :)

Consider a modern cpu running at 3ghz. It can retire some instructions on every cycle. Light can travel one mm in that time. That means the part of the core that decodes the incoming stream of insns is effectively outside the lightcone of the part that retires instructions.

I make it 100mm, not 1mm.

Then the speed of light is still not slow, cpus are just really fast. Point being, everything is relative, and lightspeed isn't necessarily the limiting factor.

c * (3 ghz)^-1 ~= 10 cm

A related point is that we can't just make a single CPU do more computations per unit time by making the CPU bigger because the finite speed of electricity (which is upper bounded by the speed of light), determines the largest size of the CPU before the different paths that electricity takes through the CPU logic gates become out of sync.

Or perhaps we are a only advanced civilization in the known universe and other civilizations are using some lo-tech method of communication like creating sounds or fire signals. Add we are looking for only high-tech modes of communications.

Thanks, I am now imagining interstellar smoke signals. I feel like that's pretty unlikely, though. :X

I'm assuming parent meant they're communicating across their own world using those forms, and we should be looking for timed puffs of smoke :)

Fantastic - but at what interval? Our lives may be measured in years, while another life form may measure itself in eons. How rapid must their oscillators be to download their own equivalent of Netflix? 1E-08 Hz? (Can we detect such slow oscillations? Is there a minimum timescale for consciousness?)

Using an SDSSD¹ they wouldn't need to tune to any specific oscillation. Just collect the data and start Fourier-ing it to find the signal.

1: Software-Defined Smoke Signal Detector

How about soliton pulses in a plasma? Isn't interstellar space mostly plasma? Its still EM radiation. Such pulses can survive incredible distances undiminished, and they are point-to-point (not broadcast). So other civilizations might be using this, and we'd never notice unless we got between them and their target by accident

And of course it would be compressed or encrypted or both. So it would be indistinguishable from noise (as mentioned in other replies)

Perhaps, if it gets a sequel, this (or similar) will be revealed as the cause of the "event" in _Seveneves_?

I put "soliton pulses in a plasma" in a search engine and everything that came back was well above my head.

Does anyone have a link to something that explains this in plain language?

In a plasma (or certain nonlinear media) a wave will not diminish in size. Its why waves in shallow seas can go for hundreds of miles unchanged, why light pulses in fibre optic cables can cross the ocean bottom without diminishing to noise. These waves are called solitons. It was my EE Professor's (Lonngren) favorite research topic back in my undergraduate days

> And of course it would be compressed or encrypted or both. So it would be indistinguishable from noise (as mentioned in other replies)

The perennial optimist in me thinks that that all the work on cracking Tor is finally going to pay off when we can decipher alien's sending each other selfies.

No reason to assume that they use the same encryption schemes we do.

Well Geoff Goldblum made that assumption, and he was able to scp his files straight into an alien workstation soooooo

To me the most straightforward thing to think about is EM waves at frequencies we can only imagine. Very different sources and detectors from what we have, therefore the radiation is undetectable to us (also very line-of-sight), but still the same physics in terms of the properties-of-the-universe required. I would imagine this increase would be developed for the same reason we have gone from KHz to GHz in a hundred-odd years: The higher the frequency the more information you can transmit per second.

So, you're thinking those cosmic rays are really symbols in an alien modulation scheme? Quasars are really light houses...?

Ha ha yeah that would be scary-cool-- the cosmic charts showing black holes to avoid and such.

The issue with high frequency communication is the power needed to sustain it, since energy goes up as wavelength decreases.

I suspect that's not the biggest issue. Developing the tech to create a and detect a modulated wave at these frequencies is way bigger, IMHO. You might be using nuclei as detectors, for example.

But in my imagination I can see this being solved.

Maybe it looks something like this:

https://www.technologyreview.com/s/611977/get-ready-for-atom...

Yeah- maybe using a nuclear version of this ("Rydberg nuclei?"). Thanks for the link!

I think the idea is not whether we could speculate in a useful way about an FTL or otherwise seemingly impossible phenomenon that we are not yet aware of. It's more about the probability that phenomena and technologies that are far beyond our current understanding can exist or not. In all likelihood we would have the intelligence and technology of ants relative to a million year old civilization. We shouldn't limit what is possible in this universe to what ants are able to comprehend and achieve. Even without such an argument, we only need to look at what we thought was possible 500 or 1000 years ago, and extrapolate forward that in all likelihood our currently understood limitations of physics will all but be irrelevant in 1000 years.

Agreed that it's a flight of fancy to speculate on these yet unknown capabilities, but that doesn't mean they aren't highly likely to exist.

I don't see it that way. 100 years ago we had a million questions about physics, and lots of fundamental values were a mystery. Today the fundamental values have all been measured to a high degree, and we have a few questions about physics and lots of them epistemological.

If in 1M years we have a different view about the universe it won't be because we were wrong about physics today. It will be about something underlying or outside physics?

Erm, seriously?

Or do you only mean classical, newton physics?

Because as far as I know, (quantum) physic is far from explained. Shure we do know a LOT more than we did 100 years ago, but I doubt we have fewer questions. I even suspect it can never be fully understood. Some basic principles, yes. But if the universe is infinitely big and small and it seems it is, there is no full understanding nor resolving all questions. I thought that mindset died out allready. Because before quantum mechanics etc. physicist actually did thought they allmost solved all questions. And then: oh. There might be more ...

I thought the whole idea behind quantum physics is that the universe is NOT infinitely small and that the minimum size / amount is a quantum.

Not at all! -> https://physics.stackexchange.com/questions/9720/does-the-pl...

We don't know what we don't know.

That doesn't imply that we don't know what we do know, however.

It doesn't seem likely that everything we've observed, discovered and experimentally verified about the universe since the beginning of recorded history is simply wrong, or that our level of ignorance about the nature of reality remains constant regardless of the data amassed.

We have absolutely no idea whether the universe or its complexity are infinite. With that out there, it leave the possibility that no matter how much knowledge we amass, it's at best infinitesimal in comparison to all that is possible to know, and at worst, our models will be completely contradicted by some new knowledge that puts previous learning in a different context.

The set of all primes is also infinite, but that doesn't mean it's possible to find an even prime number greater than 2... the universe can be infinite but that doesn't imply the laws governing it are also infinitely varied.

My point was not to state the truth but to show the possibility. Unlike prime numbers, the historical pattern is that our model of reality has changed fundamentally several times.

An easy, however unlikely, example of what could change it again is to find out we are in a simulation.

> nature of reality remains constant regardless of the data amassed.

It does not remain constant. But it remains indeterminable. Ie we can say we know something about the universe. But we cannot say we know x % of the universe simply because we have no way of knowing what 100% is...

We do know that we don't know what we don't know though, which should hopefully reduce the urge to make overly confident statements about the limits of reality.

Every kind of matter that we know about makes up less than 5% of the believed matter in the universe. What's the rest? "Dark matter" and "dark energy" which are effectively empty placeholders. We know almost nothing about them, and yet they're the overwhelming majority of what exists.

Maybe they'll turn out to be boring and useless. Maybe they have even more complex interactions than ordinary matter does. About all we can say today is that there's a mystery 20x more massive than all known matter.

'Almost nothing' is not quite right. We know the fraction to 3 or 4 decimal places. 'What it is' may still be a question but we know precisely what it does

Describing the amount there is and that it exerts gravitational pull says almost nothing about it, assuming it's as complex as anything else in the universe.

We also know that, other than via gravity, if it does interact with matter or EM radiation at all it does so spectacularly weakly.

Sometimes I wonder, how confident were our ancestors when they thought fire was an element, or when the Egyptians made mummies and hoped they would come back to life. Did they have the same level of confidence as we do today? That the "fundamental values have all been measured to a high degree"?

If that's the case, then we can be as wrong as they were.

> Agreed that it's a flight of fancy to speculate on these yet unknown capabilities, but that doesn't mean they aren't highly likely to exist.

Right, but since we have no scientific basis for figuring out which capabilities those would be, the reasonable guess is that EM is the best means of communication. It's more likely that we've figured out some basic physical limitations, even if there exists technologies within those limitations far beyond what we've though up so far.

Sure, and as I mentioned in my comment, I agree there isn't much value to speculating what these unknown phenomena or technology are. But, the value to recognizing that there is non-zero probability that they exist prevents us from making overly confident statements such as "the reason we haven't seen radio signals from other civilizations is because we are the only intelligent species in the universe"

>Agreed that it's a flight of fancy to speculate on these yet unknown capabilities, but that doesn't mean they aren't highly likely to exist.

It's just as likely that there are constraints on what is possible that we are not aware of. Take Newtonian physics for example. It turns out physical systems are significantly more constrained by relativity than Newton would have supposed. Relativity makes less possible, not more.

We might assume that super advanced civilizations can do things based on our understanding of physics, but we might be wrong. A Newtonian physicist might assume an advanced civilization could accelerate rockets to arbitrarily fast speeds and get to the nearest star in less than 4 years, but would have been wrong.

At 1 g of sustained acceleration you do get to nearby stars in a number of years.

The big impact of relativity is that less time passes on the ship.

A Newtonian physicist would also have known that it would take an awesome amount of fuel to accelerate to very high speeds. Being unaware of nuclear power they would have concluded that it's utterly impossible to go fast enough to reach even the nearest star in reasonable time frames.

> Relativity makes less possible, not more

That's not strictly true. Before relativity, time dilation was not know to be possible.

This is for much the same reason that we could transport everything in our civilization by people carrying things around on Segways, but we don't, because why would we deliberately choose something suboptimal?

In some high profile military simulation exercises, the "Iran" side used motorcycle couriers to side-step the "US" advantage in signals intelligence. Perhaps other civilizations which manage to survive know something that prompts them to use highly directed, highly efficient spread spectrum technologies which are very hard for us to detect?

Perhaps the universe is much more dangerous for intelligent beings than we know in our youthful naivete as a species?

Perhaps other civilizations which manage to survive know something that prompts them to use highly directed, highly efficient spread spectrum technologies which are very hard for us to detect?

Perhaps the universe is much more dangerous for intelligent beings than we know in our youthful naivete as a species?

This is terrifying.

"The Three-Body Problem" (& its sequels) are a fantastic exploration of this terrifying idea.

Besides emissions security, perhaps there's the equivalent of "never underestimate the bandwidth of a station wagon full of mag tapes" (with, say, a lattice of atoms of different types instead).

I don't think it's really worth considering as a realistic reason for societies choosing suboptimal technologies, but maybe some sort of Skynet scenario is possible, or something more like Frank Herbert's Butlerian Jihad[1].

https://en.wikipedia.org/wiki/Butlerian_Jihad

"had been a semi-religious social upheaval initiated by humans who felt repulsed by how guided and controlled they had become by machines:"

Boy, that rings true right now. I kind of hope that happens.

Yeah in the books the universe life is kinda shitty for tens of thounsands of years because of the restrictions on "thinking machines". It is pretty much a blanket ban on much above a 80s level non networked pc. Anything that breaks it is pretty much black market good or used an excuse for military take over by a stronger feudal house. All automation pretty much requires a human in the loop. Also any machine a "in a image of a man is banned" also pretty much a prosthetics will get the owner killed. The Dune universe is a dystopic hell hole for anyone not a member a noble house or an administer for Chom mega-corp.

> Even on the crazy fringe frontiers of real science, I am not aware of any candidates for communication any better than EM.

There is one, and it is essentially

> people carrying things around on Segways

Electromagnetic radiation must obey the inverse square law. It spreads spherically through space, so required power for a given SNR raises with distance squared.

Moreover, there are severe interference issues. Once you have several systems communicating on the same bands you get more noise in the relevant frequency bands.

Unlike waves which don't self-interact (i.e. obey the superposition principle, are linear), matter is coherent. If you shoot a hard drive at a distance galaxy (with greater than escape velocity), it may take significant time to get there, but you can travel arbitrarily far for essentially the same energy, as a first approximation.

Of course, as a second approximation there is necessity of guidance/control (because of finite motor precision, target uncertainty, etc), but also the possibility of harvesting energy or photon momentum from stars en route.

Aside from the expansion of the universe there's no theoretical limit as to why a sufficiently advanced probe couldn't propagate information arbitrarily far (if it "refuels" periodically, then its total energy usage is proportional to distance, i.e. linear, but launch cost stays bounded).

In the worst case (perhaps for cosmically large distances) it'd need to colonize a planet en route to rebuild a pristine copy of itself.

"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway."

–Andrew Tanenbaum, 1981

https://what-if.xkcd.com/31/

"The only way to actually reach the FedEx point is if transfer rates grow much faster than storage rates. In an intuitive sense, this seems unlikely, since storage and transfer are fundamentally linked—all that data is coming from somewhere and going somewhere (...)"

https://en.wikipedia.org/wiki/Sneakernet

EM doesn't have to spread spherically. There is such a thing as directional antennas, spotlights, or even lasers. Yes they spread too, but throwing a hard drive at distances on the scale of light years isn't going to be precise either. Go far enough and you won't hit the galaxy you wanted to.

Directional antennas still obey the inverse square law, because the beam still diverges as it travels. So the amount of energy that you spend sending the signal gets spread over a larger and larger area, meaning that at any given point in that beam, the signal is weaker and weaker, until it gets lost in the noise.

And even lasers diverge. An ideal laser has some minimal divergence that is inherent and cannot be overcome (if I understand correctly, it's because diffraction is non-zero even in vacuum). A true Bessel beam doesn't diverge - but it does not have a boundary, and hence requires infinite energy.

In order to achieve a Rayleigh length (effectively the "range") that is smaller than the distance from Earth to the nearest star, a (visible) laser should be approximately 40 kilometers wide. The effective range scales as the square of the beam waist, so you can communicate with the Andromeda galaxy using a laser just a little smaller than Neptune.

> Go far enough and you won't hit the galaxy you wanted to

This can be solved, in the limit of large distances (i.e. many galaxies away), by the aforementioned method of refueling/rebuilding/re-guiding along the way. But between each galaxy there's a vast, barren chasm to cross with little resources, I concur.

>which is a characteristic of the universe that it does not seem to allow any faster-than-light communication

Great answer, but do you have more information on this?

I thought quantum entanglement allowed for teleportation of information at faster-than-light speeds. Yes, there is the original information being parcelled and shipped at slower-than-light speeds, but the individual act of disentangling particles can act as a faster-than-light signal.

Great answer, but do you have more information on this?

PBS SpaceTime. The Speed of Light is not about Light: https://www.youtube.com/watch?v=msVuCEs8Ydo

Information is defined in such a way as it may never travel FTL.

When entangled particles reveal their states, they do not at that point in time transmit any new information. The information was actually encoded into the entangled pair which travelled at less than light speed to that destination.

I imagine this answer is probably unsatisfying and counterintuitive to you, as it is to me.

I think neutrinos would be viable with real world physics. They can go through anything which would be pretty useful and you can direct it easily.

We don’t have an easy way to detect them but a more advanced civilization might.

That's the paradox, isn't it? You want something that doesn't interact with matter until to reaches the detector, where you want it to interact as much as possible.

> You want something that doesn't interact with matter until to reaches the detector,

Axions [1]!

[1] https://en.m.wikipedia.org/wiki/Axion

That's not a paradox, it's just the property that good communication medium should have.

EM waves have this property thanks to effect of resonance in the reciever. Neutrinos will have this property (but better) once we learn how to emit and detect them efficiently.

Wanting two opposite properties simultaneously is paradoxical requirements.

And no, resonance isn’t the reason for EM. Faraday cages are not resonant, and they block (certain frequencies of) EM. Neither are lenses, and they make directional detection of EM much easier. And, honestly, I’m not sure what the right word is for individual photons being absored by atoms or molecules.

EM is a fundamental force. Everything interacts by fundamental forces, even neutrinos, but even though I think neutrino communication is cool and potentially useful in limited circumstances, it’s not reasonable to just assert that aliens will be chatting interstellar with them. EM is about the best you can get for interstellar because there’s nothing in the way to block it. Neutrinos are what you would use if there is a lot of stuff in the way — like, say, a planet or a star — and you benefit from the slightly lower lag time of going through it instead of bouncing around it, or you can’t go around it because thing you’re talking to is in the middle of it.

Even if you posit that super advanced alien technology can make wormholes, the only way you’re going to get anything other than light going through them is if they turn out to be really small and it’s better to have a high energy electron (=small DeBroglie wavelength) beam going through them.

In transiting space, the problem is far more the detecting than the getting through tings.

Space is mostly not-things.

(With some interesting exceptional cases.)

I'm not aware of any useful neutrino lensing mechanisms, either.

But we didn't suspect EM radiations existed until we started understanding electricity, magnetic fields, etc. What else do we not suspect exists today but will be obvious in 50 years?

We knew light existed long before we understood electricity and magnetic fields, even those had observable effects to us long before we discovered them.

That is because we could "see" it. Imagine if we were not able to see. Could we have known the existence of EM?

Or think if we were not able to hear. Could we have imagined the sensation of sound, or the concept of music?

Human beings are so pathetically stupid that they think that their intelligence and sensory capability are at the limits of what is possible.

>That is because we could "see" it. Imagine if we were not able to see. Could we have known the existence of EM?

Probably, it has a number of physical effects, like heating up the areas that it hits, there is probably quite a lot we could have deduced about light with no eyesight, as long as we lived somewhere EM existed had a noticeable effect, which is just about everywhere.

> Or think if we were not able to hear. Could we have imagined the sensation of sound, or the concept of music?

Of course not, but that wouldn't prevent us from understanding the concept of pressure waves.

> Human beings are so pathetically stupid that they think that their intelligence and sensory capability are at the limits of what is possible.

What? We know our sensory understanding has sever limits, no one that graduated the third grade thinks our sensory capability are at the limit's of what's possible. Everyone that has ever seen an x-ray knows this. To quote Brother Cavil:

I don't want to be human! I want to see gamma rays! I want to hear X-rays! And I want to - I want to smell dark matter! Do you see the absurdity of what I am? I can't even express these things properly because I have to - I have to conceptualize complex ideas in this stupid limiting spoken language! But I know I want to reach out with something other than these prehensile paws! And feel the wind of a supernova flowing over me!

> as long as we lived somewhere EM existed had a noticeable effect, which is just about everywhere.

You should have understood that I meant otherwise. Of course, if we could notice the effect of EM, that could trigger an investigation eventually leading to the discovery.

>we know our sensory understanding has sever limits...

Did you really think I implied that no one knows the limits of our built in senses? When I said sensory capabilities I meant the stuff we can sense, directly or indirectly (By indirectly, I mean by the help of another device, to make it very clear).

> You should have understood that I meant otherwise. Of course, if we could notice the effect of EM, that could trigger an investigation eventually leading to the discovery.

Can you suggest an environment conducive to life that isn't exposed to EM radiation? Life itself creates EM radiation.

> When I meant sensory capabilities I meant the stuff we can sense, directly or indirectly (By indirectly, I mean by the help of another device, to make it very clear).

I can't prove God doesn't exist either, but that doesn't make it logical to conclude that we will one day be able to harness the power of God for FTL communications, but this is what you're expecting. If there are fundamental forces left to be discovered then they are not having any observable effect on the world, making them unlike all other fundamental forces. This makes them unlikely to ever be discovered.

>Can you suggest an environment conducive to life that isn't exposed to EM radiation? Life itself creates EM radiation.

There is nothing in the definition of "life" that warrants an ability to observe EM radiation or create it for that matter..By the way, what is the definition of "life" that you are using here?

>there are fundamental forces left to be discovered then they are not having any observable effect on the world..

So just because we haven't discovered something, does it mean that that thing is not observable at all? We are still discovering "things" in our own body, let alone in the entire world. The fallacy that human beings are capable of detecting every observable (by observable, I did not mean observable with our current tech) phenomena in this world is exactly what I was indicating before.

> By the way, what is the definition of "life" that you are using here?

An incredible loose one. Basically any process remotely complicated enough to call life would be producing infra red radiation at least. From there the evolutionary pressure to be able to sense it is huge. Eyesight on our own planet could have evolved to see heat long before sunlight.

Unexplained physics today is primarily down to dark energy and dark matter.

The good news is that collectively they represent about 95% of the universe. So, that's a huge quantity of phenomena that we can't currently explain!

The bad news is that we have no local evidence for either; they only seem to have measurable effects over cosmic distances. So that implies that, even if we fully understand them, it's unlikely we will be able to harness the mechanisms to accomplish things at the scale of our civilization.

And--neither provides any evidence of FTL effects. So it's even less likely there is some amazing new form of FTL communication hiding in them.

They could just high focus beams of extremely energetic photons or even gamma ray transmitters with encoding that’s basically “noise” because we grew and evolved around it. There was one theory for Tabby’s star that it was basically a transmission beacon and we happened to see the transmissions because we are in the line of sight.

so the sun could not be a complex communication device? programmed by "someone" billions of years ago...

Here's a faster than light issue I have:

Take a really weak light source. Aim it at a beam splitter, say, at 45 degrees to the line of the light. Assume that the light source is so weak that typically we get a photon only one a second or so (not strictly necessary for the idea).

Then each photon (there are standard claims that could also use an electron, proton, neutron, etc. but all photons travel at the speed of light, and using just light we don't have to worry about the electric charge of an electron or proton) has a quantum mechanical wave function. From the lessons we get from Young's double slit, the Michelson-Morley experiment, the Mach-Zehnder interferometer, the Fabre-Perot interferometer (right, my ugrad physics prof liked optics!), we believe at the beam splitter the wave function becomes two parts, one part continuing straight through the beam splitter and the other part going off at 90 degrees.

Now sit and have a brewski or two; finish a physics Ph.D.; get married; have a lot of kids; get them all through college; and, I omitted, for the beam that went through the beam splitter, have it bouncing around in a box full of perfect mirrors or resting in some Bose-Einstein condensate, and then get out a very sensitive photo detector and try to detect the photon.

Okay, for a perfect beam splitter, have a 50% chance of detecting the photon. Suppose we do, or, suppose we just in the beginning did this stuff for 1000 individual photons and pick one of the photons where we do get a detection from the part of the wave function close to us (the other half of the wave function is way past the nearest star by now).

So, we get our detection. We know the energy we get, just proportional to the frequency of the light. So, our detector gets it all -- the wavelength, the frequency, the momentum, the energy, maybe the polarization. Fine.

Now, folks, what the heck happens to the other half of the wave function, the half that went 90 degrees and by now is part way out of the galaxy?

No sense in saying that half just disappeared. For one, ET way out there 50% of the time could detect the photon. For another, we could have a mirror out there and have that half of the wave function return to us and do a Young's double slit or Michelson-Morley experiment where both parts of the wave function definitely get involved. So, no saying that the half of the wave function nearly out of the galaxy doesn't matter.

I know; I know; that half of the wave function gets old and tired, goes de-coherent, etc., but such stuff raises other little issues such as conservation of energy. So let's assume that, even after all these years, both parts of the wave function are still nice and healthy just like they would have been in Young's double slit, the Michelson-Morley experiment, etc. Besides we believe we can detect photons 13.8 or so billion years old, and, really, some of those may have their wave functions, from being deflected here and there for all those years, in multiple parts.

But we know also that we and ET can't both detect the photon. So, that part of the wave function out there with ET can't just do its own thing -- with us and ET, there will be exactly one detection.

Okay, when we get the detection, supposedly the other half of the wave function, some light years out there where ET is, disappears, folds up, evaporates, leaves town, becomes null and void, instantly, just as soon as we make our detection. So, sorry guys, that looks like an instantaneous effect (I didn't say communications) over a distance of light years. So, the naughty boy in his room running the simulation for our universe, as soon as we detect the photon, has to run around all over the whole darned universe and clean up any stray pieces of the wave function of the original photon, and there may be thousands of those. During this clean up, the whole simulation (think of a data base problem!) has to stop. So, the simulation has to run all over the universe or a lot of it in zero time -- that's an effect infinitely fast!

I know; I know; this is not faster than light travel for us, but it looks like faster than light travel for the naughty boy's universe simulation program.

Now from this, what can we say about how the quantum fields we believe in actually have to work? Is there something?

E.g., suppose both we and ET have really sensitive gravitational wave detectors and, thus, can detect each of the two pieces of the wave function as they pass by. Uh, the photon has to feel gravity and also create gravity, and, thus, BOTH parts of the wave function have to create gravity. So that part of the wave function that ET gets MUST create a gravitational wave as it passes by and MUST create a gravitational wave as it disappears instantly as we detect the photon. We're getting close to faster than speed of light something or other ...!

Okay, suppose ET is 10 light years away and we want to spend the next 10 years setting up an instantly fast communications channel.

We agree to send one bit a second.

We use the beam splitter, ..., etc. as above.

If we are using our elecgtro-magnetic detector, the for each photon we have not detected, ET gets both a gravitational wave detection and a photon (electro-magnetic) detection.

For each photon we do detect, ET gets neither the gravitational nor the electro-magnetic detection.

If we put our detector in the path of our half of the wave function, then we get a detection half the time which means that half the time ET gets neither a gravitational nor an electro-magnetic detection.

If we do not have our detector in front of our half of the photon, then ET always gets the gravitational signal and half the time gets the electro-magnetic signal.

So, suppose each second (since when we started spending 10 years setting up the communications channel) we sent 1000 photons a second.

Now for one of those seconds, if we are using our electro-magnetic photon detector, ET gets about 500 gravitational wave detections and 500 electro-magnetic detections. If we are not using our photon detector, then ET gets 1000 gravitational wave detections and 500 electro-magnetic detections. So, once we have spent 10 years setting up the communications channel, we can communicate at data rate of 1 bit a second with ET instantly.

I don't really believe it, but first cut it looks that way!

Now each second, we either put our detector in the path of our half of the wave function or we don't.

> BOTH parts of the wave function have to create gravity

Nope. Wave function obeys gravity but it does not create gravity. Gravity is created by matter/energy and wave fuction is not that.

The energy of the photon must generate gravity and must be somewhere, e.g., covered by the non-zero parts of the wave function.

> flights of fancy

It seems presumptuous to dismiss the entirety of non-Standard Model physics thusly. Axions [1] are one of my personal favourites.

[1] https://en.m.wikipedia.org/wiki/Axion

I agree with your praise of EM. But hypothetical aliens might want to explore some trade-offs. The game we are playing is to find some advantage in the known physics of a medium even if we know of no practical way to create and detect those signals.

Neutrinos spring to mind: we can't work with them because they don't interact with matter. But if you had some technology that could interact with them, you would have the advantage that nothing in the natural world screens them much.

Even if that technology was much more cumbersome than radio, aliens might have special cases uses for it (e.g. for signalling to and from their secret base at the centre of the Earth).

Neŭtrino detectors are coming along nicely! For example, see this paper on the compact COHERENT detector, which is theoretically portable!

https://arxiv.org/pdf/1708.01294

It can only detect neutrinos <50 MeV but still, wow.

Production, modulation and beam forming (and then demodulation and background removal) is a significant challenge, but neutrinos have many advantages for signaling for a galactic civilization, such as not needing to worry about occlusion.

Staying grounded in current physics is not a good idea. Humans are primitive and other civilizations capable of traveling the solar system is not.

Its like if you would ask a human 500 years ago how he think aliens would travel. He would say something likely in that age according to his understanding. We are exactly the same.

> Maybe, but it's still easier to build EM detectors, and EM emitters, by a lot.

It's easier to build paperclip factories than iphone factories but we are awash in both and some people own more iphones than paperclips.

Why on earth would you build EM emmiter if by bit more effort you could have device for unobstructible communication?

This is a very panglossian statement. You just recited a version of the "Best of all worlds" fallacy.

>If you want to go off on flights of fancy, then anything is possible, but there's no way to say anything useful about it.

I would guess, though I could be completely wrong, that a civilization that both had access to far more advanced 'sci-fi' level technology and wanted to broadcast it's existence would also have an understanding of the technology other civilizations would have access to and would choose to broadcast using numerous 'ancient' technologies that more privatize civilizations could pick up on.

When we sent probes out into space to broadcast ourselves, we realized we couldn't just write a message in English and as such tried to send numerous different ways of conveying information, some linguistic and some not.

i feel this is too hyperbolic in the wrong direction. there is clearly more beyond our current knowledge of physics, so why is it beyond the realms of reality to assume that something in that subset of all knowledge is useful? we didn't even know of the possibility of gravitational waves a century ago and just confirmed their existence. so why is it reasonable to say they couldn't possibly be useful for communications?

in dealing with the eventuality of alien civilizations, we must open our mind. it is certainly probable they communicate in ways we can't understand, even if they are simply evolutions of our current communication methods.

Even if a sufficiently advanced civ out there is using something like quantum entanglement, they mostly likely didn't just jump from smoke signals to quantum entanglement. So we might be catching signals from the say 500 years while they used radio waves.

But isn't there a certain probability we missed those radio waves back when we didn't know radio and now the earth is receiving more sophisticated signals humans can't yet analyze?

Sure, it's also possible the universe immediately surrounding us was teeming with life a billion years ago and we just missed it all anyway.

We can only try our best with the current means we have available.

We could have missed those signals millions of years ago, but we could also start receive a civ's first ever radio broadcast tomorrow (that would be incredibly lucky).

> we could also start receive a civ's first ever radio broadcast tomorrow (that would be incredibly lucky).

not a chance. Our own radio transmissions barely go past the solar system before going under the noise floor.

Maybe not their first radio broadcast, but possible one of their early, directed ones…

Look at us as an example though. We've had radio for a little over 200 years and already realize its limitations.

Smoke signals will have been around for a lot longer than radio. Smoke signals will have been around for 99.9% of the timeline and then 0.1% radio before quantum. To an outside observer it would look like radio was just skipped.

If you scale human civilization into a 1 year time frame we invent radio at 3PM on December 31st.

500 years is a very short period of time on the cosmic scale.

Just so you know, entanglement can't be used to transmit data. You must still transport the particles which have become entangled. When you observe them later you are only "instantaneously obtaining information" through the process of elimination.

Assuming that we are right that matter can't 'travel' FTL, it's entirely possible that signals can (despite our current inability to understand how) somehow travel FTL. Once discovered, that method might be a thousand or million times FTL.

Such a relatively instant means of communication would become the defacto standard. Antiquated EM methods and equipment would be forgotten. Noone would be listening for it, just as very few today would recognize semaphore flags, smoke signals, or telegraph codes.

Today we'd not be eligible to join that club. And if we choose to remain certain that it doesn't exist, our determined ignorance would keep us locked out. If we conclude that we aren't special, that there -must- be life elsewhere, then the only logical thing to do is to keep our minds open and keep looking for clues.

We can't ever decide that we know enough. A century ago, the Milky Way was the whole universe. A few more observations changed that forever.

Yet most of the old technologies we've invented are still used by hobbyists and collectors. Morse hasn't ceased to exist, neither have steam trains, analogue radio or horses. None have been forgotten. People are still making crystal sets and wave traps. There's a whole niche on YT of people making primitive huts, fires, bows or making it their weekend hobby through re-enactment etc.

Some of the details are lost like maintenance details, advanced fault finding etc, but the core remains.

After a century of radio and electricity it would be rather silly to only search for other signs of life on the new system of FTL communication we just discovered. It still gives no certainty that the candidate alien discovered the same defacto standard for FTL comms or that theirs will be recognisable.

Any rational search should try and encompass both and probably still emphasise the analogue as any advanced civilisation would very likely go through that phase first, just like we are. We'd be likely to catch more possibilities that way.

The point was that we can't assume that because there are no civilizations using EM for comms, there are no civilizations.

The claim isn't that matter can't travel FTL. It's that information cannot. Our current understanding of physics makes this rather fundamental and overturning it would involve seriously drastic changes to our understanding of reality.

Being able to send a message at a million times FTL would make it really easy to send messages back in time.

The claim isn't that matter can't travel FTL.

Actually that is exactly what physics says. Anything with whatever mass, as its relative velocity is accelerated, approaches a mass of infinity as its velocity draws nearer to c. Information, on the other hand, has no mass ...

In the 1890s, Lord Kelvin stated that physics was essentially complete. m'Lord was oh, so wrong.

Care to try again?

https://en.wikipedia.org/wiki/Faster-than-light#Superluminal...

"Faster-than-light communication is, by Einstein's theory of relativity, equivalent to time travel. According to Einstein's theory of special relativity, what we measure as the speed of light in a vacuum (or near vacuum) is actually the fundamental physical constant c. This means that all inertial observers, regardless of their relative velocity, will always measure zero-mass particles such as photons traveling at c in a vacuum."

I always liked the theory that if you go stand above an ant hill and scream all day at the little creatures, they'll still have no concept of your attempts at communication.

So then similarly, it seems possible that advanced intelligence could be screaming at us but we're too "simple" to be able to understand them or even be aware of their presence.

The bit that saddens me is the realisation that those ants will probably find "aliens" one day, the termite mound half a mile away, and likely fight terrible wars, but even if not, neither side will ever see sunrise over central park

Similarly every ant in the anthill could be screaming at you all day, and you'd have no concept of their attempts at communication

Common tangential theory: Any advanced civilization compresses their data so its signals will become indistinguishable from noise

But surely an advanced civilization would realize theres less advanced lifeforms and would thus send the simplest type of message possible. After contact is established, they could then send their ultra-compressed data.

Or being advanced, this civilization would be extremely cautious of any other civilization, and would most likely not facilitate communications with others.

For a civilization to survive and be qualified as being advanced, not only implies being smart enough to develop some technology but smart enough to know when NOT to use it. e.g.: let's not use nuclear warheads, let's not use grey goo, let's not communicate with possibly agressive alien civilizations.

That just depends on the delta between civilizations. They might've advanced way beyond us and they don't have the means to fallback to human method of communicating.

Why? We don’t simplify high bandwidth satellite radio signals for the benefit of the Sentinelese people, and unlike extra terrestrial life we can be certain that the Sentinelese are sentient, and also that they can (given enough time, but less than even a RTT to Andromeda) learn both how to tune in and what the signals we’re broadcasting ultimately mean.

I mean, of course we might be missing out on things we can't technologically grasp yet... but even if we knew it existed we wouldn't know what to do with it yet.

If they're super smart, and actually care about communicating with less-advanced civilizations, then they would probably broadcast through mediums that are considered "old tech" for them, but possibly current tech for those civilizations.

Humans aren't broadcasting into space with any pre-EM technologies. It's not so much that we don't care about less-advanced civilizations, but that broadcasting in a way that life forms could see/hear without electronic sensors would be many orders of magnitude less efficient for us. It's simply impractical.

Maybe there's another form of communication we haven't discovered yet that's so much faster and more efficient (like Star Trek's "subspace") that everybody else in the galaxy uses that instead. For them to send radio waves to Earth might be like us pointing Morse lamps at Alpha Centauri.

Trying to detect alien life by scanning the EM spectrum sure is inefficient. Maybe it's the best we can do, but if there were something better, I could totally see why we'd abandon plain old radio waves.

does anyone know if there is any theory to support the idea that sufficiently advanced civilizations rely on something other than radio waves or light to perform communications?

This implies a common assumption among people: That any civilization out there is automatically going to be more advanced than we are.

If you believe that the universe started with the Big Bang, then (IMO), it's reasonable to believe that we all had pretty much the same amount of time to evolve and develop civilizations. Asteroid events notwithstanding.

To me, believing that all beings average about the same place in the development cycle, it makes sense to look for the signals we know, rather than the signals we don't know.

But I'm no scientician.

In 500 years we've gone from signalling towers to lasers, fiber and RF. If someone got a 10,000 year jump on us and has a technological improvement rate close to us, we don't know the scale, frequency, or means of communication. There's a lot of physics we know, but there's also more we don't know.

Also, I can't use language bi directionally with a plant no matter how hard I try. Maybe we're the plants. Maybe they don't have language.

There's a great short story by Harry Turtledove called "The Road Not Taken" that tries to jostle that view. If you can find a copy of it, worth a read.

https://pastebin.com/aJQfubrK

The universe is about 14bn years old. Earth is about 4.5bn years old. Humans are about 100k years old. Writing is about 5k years old. Radio communication is about 150 years old. The laser is about 50 years old.

So that window holding our current level of communication abilities is 0.15% to 0.05% of our species' age, and our species is in a similarly tiny window.

The age of the Sun is ~4.6 billion years, but it's rather young as most other stars in our galaxy are 10 billion years old or older.

That would mean most civilizations in our galaxy could be very much older than ours.

Radio only came about 100 years ago for us. Some new form of communication could be 100 or 1000 years out, which is no time at all on these scales.

Not an expert, so someone who is (I'm sure we have several on HN, hopefully one will reach this point), please jump in...

But life as we know it requires small but essential smatterings of "heavier" elements like potassium, iron, calcium, etc. Seems like we may need one or more cycles of stars forming and dispersing these elements into the interstellar medium to then form a solar system with enough of these elements to have life "as we know it." (Not to mention having a rocky planet for the life to live on.)

Stars that can produce elements up to iron and spread it through a supernova are massive and have relatively short lifespans of 10-30 million years. Since the Universe is 14 billion years old, we have had already more than a hundred generations of such stars before a 10-billion years-old planet has formed, so the necessary elements are probably there.

Yet another reason I love HN. Thank you. ;-)

Problem is, if they're at our level, their signals aren't going to be detectable.

Most people don't seem to realize this. Even if the nearest star had an earth level civilization, we wouldn't be able to detect its signals[1].

[1] https://www.seti.org/faq#obs12

I ain't no astrologist either, but there's also an assumption other beings would have similar biology to us, it seems.

To the side now with assumption they might communicate chemically only between themselves... WHAT IF their clock rate is way slower than ours? Like snails, or plants. Their bitrate of communication would be undetectable to us, if they're way slower. I suspect it would be detectable if their rate is higher though.

Gravitational waves could be a prime candidate. Assuming that you have enough power to create one it could travel to the other side of the universe without any kind of interference. Whether you can embed a message in them is a whole different story though, we couldn't possibly know with our current understanding.

The concept is used in the "The Three Body" trilogy.

Very advanced civilizations could learn how to create targeted worm hole like structures to send information through it using real world physic rules that we don't know yet

It's possible that they are using the orbital angular momentum of photons to communicate and we would not have discovered it, because we are not yet listening for it.

If every civilization that invents a radio gets past this phase we are now very fast (as we are soon going to do) advanced civilizations don't bother to encode their messages in a way that we listen now (we look mostly for phase and amplitude encoding)

Photons carry both Orbital Angular Momentum (OAM) and Spin Angular Momentum (SAM) OAM is relatively recent discovery (1990's). They exist just not in the light beams level but also at the single-photon level (very surprising).

Detecting photons with orbital angular momentum in extended astronomical objects: application to solar observations https://www.aanda.org/articles/aa/pdf/2011/02/aa14844-10.pdf

Optical orbital angular momentum (2017) http://rsta.royalsocietypublishing.org/content/375/2087/2015...

Entanglement of the orbital angular momentum states of photons https://www.nature.com/articles/35085529

I think the people who downplay this question forget that many technologies we take for granted today would be considered impossible by older understandings of physics.

Or they use EM but are allot more efficient with communication such that they don't leak.

These SETI signals, if they were of intelligent origin, would be showing just how dumb these aliens are. To send a presumably fairly local signal in such a way that it wastes such vast amounts of energy that it can be picked up 3bil ly away would seem like a serious transmitter design flaw.

Why? Literally the cheapest thing to use acrossm interstellar distance is your local star in the cosmic equivalent of flashing in Morse code.

Say you want to communicate between 2 star systems all you need to do is to position say a polarizer between at the edge of each solar system such as that polarizer can obstruct a suffiently large portion of the star from the point of view of the system you want to communicate at say the edge of a solar system it won’t even have to be that big.

You use the polarizer to modulate the passing light and encode your message onto it.

Something like KIC 8462852

Yes but it can be done on a much smaller scale.

The smallest exoplanet discovered is Kepler 37b it’s smaller than mercury.

And planetary transitions are hard to detect because they are very time sensitive if you put something in a solar synchronous orbit between two planetary system a thin polarizing sheet which can be as thin as a solar sail can easily serve as communication device.

Any civilization needing one would easily be able to drag an asteroid which should have enough raw material to build a polarizer a few 1000’s of KM in size.

On your specific comment regarding quantum entanglement see https://en.wikipedia.org/wiki/No-communication_theorem

Definitely not a stupid question, just the wrong question IMO. The real question would be do we have any reason to believe that they do still use radio?

We've had radio for just a little over 200 years and we've already realized its limitations. The fact that we can even speculate about quantum communication leads me to believe that radio is definitely NOT the end-all-be-all. If you scale human civilization into a 1 year time frame we invent radio at 3PM on December 31st. It's successor likely emerges January 2nd at the latest. Radio communication is likely a blip.

Radio is efficient over short terrestrial distance but horrible for long (galaxy scale) distance communication. If interstellar travel is feasible at all it will have to be at FTL speeds and an FTL communication system would be necessary.

If FTL is truly impossible then it doesn't seem like there is much point in listening since everything is so incredibly far it's irrelevant even on a species-level or planetary-level time scale. I believe that everyone at SETI must believe FTL is possible because otherwise it truly is a waste of resources.

> The fact that we can even speculate about quantum communication leads me to believe that radio is definitely NOT the end-all-be-all

Who is it that's speculating about quantum communication? Certainly not physicists. It's mostly just IFLScience!-class journalists seeing a term like "quantum teleportation" and assuming that it means start trek is real and write their articles based on that.

> I believe that everyone at SETI must believe FTL is possible because otherwise it truly is a waste of resources.

If everyone at SETI believes that mysterious FTL communication exists, then why do they spend all their time looking for EM signals?

Because that's what we have today, so that's what they have to work with. It's a shot in the dark in the hope that we might be able to find a remnant sign.

If we detect radio signals in another galaxy but FTL is impossible who cares? The human species will be extinct before any interaction can occur. It's probable that whatever species sent them is already extinct because it's at least 3 billion years old.

If c is the ultimate speed limit there's really no point in looking anywhere else because everything else is so far away it's irrelevant.

Knowledge doesn't need to have a practical purpose to be satisfying.

The problem is that you can either have FTL or causality, but not both. Also, relativity has been extremely accurate as a description of the universe, particularly on the macro level that you and I happen to inhabit. I'd say that I'd never bet on FTL being real, but to be honest I'd be surprised if you ever found anyone to even lay you odds. And as you say, that does make SETI rather pointless even without considering that the SNR to Mars on a good day is, what, ~11 dB?

We get generation ships, and if we are extremely lucky, we may have some very patient pen-pals, but warp drives, ansibles, and their attendant paradoxes are pretty unlikely to be features of this universe. Personally I prefer a knowable universe to a tourable one.

So you're saying we should shut down all of the large and Radio and space telescopes, because it's pointless to look at things you can't visit?

Not just visit, anything. You'd never be able to communicate. The SNR is such that it would always just be noise.

If FTL isn't possible then the end result of listening is simply the confirmation that something else exists and it stops right there.

Conversation isn't the only thing you can do with messages. Alan Turing didn't crack Enigma so that he could have a lovely chat with the Germans.

Don't you think there's at least a little bit that could be learned by listening to alien communications from centuries ago, other than the fact that it exists?

If such signals were found, would you really stop reading at the headline "alien communication discovered"?

>"If interstellar travel is feasible at all it will have to be at FTL speed"

Why is that? Special relativity already demonstrates that space contraction at near light speed would allow interstellar travel at human scale duration, with the side effect of time dilation for moving observers.

See: https://en.m.wikipedia.org/wiki/Twin_paradox

Why would you bother taking a trip that involved leaving your entire species hundreds of thousands, even millions of years behind you? It would be energetically expensive, and the civilization that launched it couldn’t expect to care or remember by the time it arrived. That might work for a small group of pioneers willing to go into the blackness, but it’s not the basis for a galactic civilization.

Even though it May not seem logical, the point is that interstellar travel without FTL speed is feasible.

Its possible, but not at all feasible. It’s also not really practical and the nature of it undercuts the usual “where are all of the intelligent species colonizing the galaxy?” arguments which tend to crop up.

> I believe that everyone at SETI must believe FTL is possible because otherwise it truly is a waste of resources.

Isn't this like saying every historian must believe in time travel? Just because you can't visit someone doesn't mean you can't learn from them.

If FTL is truly impossible then it doesn't seem like there is much point in listening since everything is so incredibly far it's irrelevant even on a species-level or planetary-level time scale.

Probably true on a species level, but you are vastly underestimating how long a planetary-level timescale is. A von Neumann probe could cover the entire Milky Way in relatively short geological time.

An advanced civilization, when looking to signal other potential civilizations, would hopefully -

- use the lowest common denominator long range communication medium (like EM waves), not the most advanced technology available to them, and

- would broadcast it widely in spatial, temporal and spectral dimensions and not worry about efficiency

We don't have much of an option but to look with the tools we have, so though it's an interesting thought exercise (and continually worth pushing for new sciences) I don't think it's actionable to assume otherwise. E.g. I don't know of any generally-accepted theory that says that sufficiently advanced civs will definitely not use what we use, so it's still worth looking while we try to discover new things :)

EM waves are, given everything we know about the universe, the obvious communication medium for advanced civilizations no matter where or who they are. Maybe somebody sufficiently indistinguishable from a god could use gravitational waves, but off the top of my head I'm not sure why you'd want to bother.

Quantum entanglement does not, as far as we know, enable superluminal transmission of information. "Teleportation" is implementation-dependent and at this point entirely science fiction. If you're going to rip something apart or non-destructively scan it, and rebuild it at the other end, which is the only "realistic" theory of how it might work, you either need to transmit the bits or the bits (heh) and then you're back to the same problem of information transmission.

Of course we don't know everything, but the discussion really ends there: we don't know what we don't know.

Sure but imagine what someone would have said before we discovered radio waves.

We don’t know that there is anything better, but given how much we don’t know it’s not unreasonable to consider that we might not have the technology to receive communications from more advanced civilizations.

I agree with you that RF is a good communication medium given what we know, I just don’t put much weight on our existing knowledge being all there is.

Do you know why people say that superluminal communication is impossible?

I said this:

> Of course we don't know everything, but the discussion really ends there: we don't know what we don't know.

I think the guy I replied to asked about "theories" of alternatives, and there isn't really anything specific as far as I'm aware; there's just this vague philosophical notion that we don't know what we don't know. I don't think anyone's denying it (I certainly am not) but there is not much else to be said on the subject. Knowing that we don't know what we don't know doesn't help us make predictions about what we don't know.

You'll want to read "The Eerie Silence" by SETI lead Paul Davies who's job is to think of this stuff.

The book covers many many possibilities for how a civilization might try to communicate or get the word out from Von Neumann probes to leaving something in our DNA, which could easily last multiple millennia to monuments...etc etc. It also covers the search for life elsewhere like looking for reverse chirality DNA on Mars (basically there is no reason all DNA found on earth should curl one way and finding DNA that goes the other way strongly suggests it didn't come from us).

I think others have it right, with what we know EM is the way to go. But I keep thinking about dark matter and dark energy and how we don’t understand them. It wasn’t really that long ago that we didn’t understand EM either. Finding radio waves was exactly like finding invisible ways to communicate. Who knows what we can’t “see” yet.

I don't know if we count as advanced, but our communications are moving towards light that's confined to fiber optic cables, and radio waves that are practically disguised as noise. We are making an ongoing effort to reduce the power level used by those communications. That doesn't seem promising for having someone detect us from a distance.

For inter-stellar communications of sufficient distance, some sort of massive object (i.e., a space ship) seems like the preferred method because it can go at almost the speed of light, but it doesn't spread out over distance, can make minor corrections to its course, visit multiple destinations, and do something such as return a message, learn about its surroundings, and so forth.

I'd guess that a civilization might go through a period where it is emitting lots of easy-to-detect radio signals, lasting maybe a century, so we have to catch them at just the right moment.

Probably sufficiently advanced could harness neutrinos? (At least in Star Trek that is proposed.)

But what's the point?

First, they have mass, hence travel slower than the speed of light, which means they are less effective.

Second, it is very hard to detect neutrinos, which means they are very bad communication medium.

I absolutely expect they use EM radiation.

Another interesting question is if they are EM radiation.

It should be the most efficient way to travel. Going from Turing machine to Turing machine, a virus with a really advanced universal exploit, impregnating civilizations like ours around the time they develop both radio tech and computers.

Civilizations with the capability to travel in that fasion would be dominant.

Neutrinos seem like a good option, if you have a good way to collect them.

Your comment reminds me of the Startrek TBG episode The Loss https://en.wikipedia.org/wiki/The_Loss

The two dimensional lifeforms were unable to perceive three dimensions. Yet at the same time, the crew of the TNG struggled to understand them.

What if alien civilisations figured it was a good move to hide themselves from hostile civilisations... Or if those that broadcast like we do were destroyed by hostile civilizations. Let's hope not I guess.

SETI more expects side-effect radio emissions than purposeful communications. It was started at a time when powerful radars [1] designed to detect ballistic missiles were deployed and this radar's emissions are definitely detectable several light-years away.

It relies on the same mentality as the Fermi Paradox: it expects that an advanced civilization will master so much energy that its waste should be visible from afar. Only recently have we started considering that efficiency, rather than wastefulness, may be the hallmarks of civilization.

But yes, everybody at SETI knows that what they are doing are stabs in the dark. It is like trying to find inhabited lands by looking for tam-tam songs along the coast or to check if there are lighthouses installed where people may have switched to GPS.

Still, if there are thousands of civilizations out there, you can bet on off-chances of detecting one. The odds are low but the rewards would be huge. Fewer discoveries would be as consequential as this one.

[1] https://en.wikipedia.org/wiki/Duga_radar

I don't think we can answer that

I mean, before we knew that radio waves exists we could not forsee the use of radio for communicating

so, I'd say that better ways of communicating relay on something that physics hasn't found yet (like, you know "that weird supersimmetry decay thing that only su-top quarks do when reacting with Stuff")

I always believed that all that SETI thing will be pretty silly if in few hundred years we'll discover how to emit and receive neutrino beams for communication.

SETI would become search for extraterrestrial intelligence that that believes it's worth a shot to emit RF to contact less advanced civilisations that at the moment of recieving the signal will be in that small time window when they used RF for communication because they had nothing better.

> My dumbass-self wonders about quantum entanglement or teleportation as means of communication we have yet to master;

We use lasers for quantum teleportation. There's no reason to believe it can be realised more efficiently without.

> I have a question... and this is probably a stupid question, but... does anyone know if there is any theory to support the idea that sufficiently advanced civilizations rely on something other than radio waves or light to perform communications?

This probably really should be five questions.

1. For an advanced civilization trying to communicate to other, unknown, civilizations like ours. In other words, intentionally trying to have our SETI folks notice them.

2. Similar, but trying to communicate with a civilization that their SETI folks have detected. E.g., they have picked up on our existence from our EM emissions and want to to strike up a conversation.

3. For an advanced civilization that spans multiple star systems, not intentionally trying to communicate with anyone else.

4. Similar, but only spanning multiple planets within one system.

5. Finally, for an advanced civilization that is only one planet, not trying to communicate with anyone else.

For #1-4, EM is the most likely answer for reasons numerous others have mentioned. For #3 and #4, the big issue would be power. If they are only intending internal communication they might not be putting enough power for us to pick it up unless they are close to us.

For #5, even if they have not discovered something beyond the physics we know, they might not radiate their EM in a way we can detect. For example, if they have a planet wide urban civilization they might have every building connected to a high speed wired communication system. The only wireless they use might be something like Bluetooth or low power WiFi that only needs to communicate within a single room of a building between their portable devices and that room's node on the wired system.

EM is quite disappointingly weak for anything except point to point communications. If you really wanted to broadcast a message, it'd be far better to use something like von-neumann probes.

Despite the fact that quantum entanglement is frequently referred to the new ways of communication, at the current state of Standard model/Quantum physics quantum entanglement does not mean interaction or information transfer. Furthermore, instantaneous information transfer is restricted and its speed is limited to the speed of light.

Quantum entanglement is rather about correlation and statistics, which is, hopefully, will be quite useful for some applications, but not for communication channel. Otherwise, it will ruin the current foundation of quantum mechanics.

I strongly recommend reading the book of Nicolas Gisin 'Quantum Chance' [1], which is quite good for the general audience to understand, what quantum entanglement actually means in the real life, i.e. in the physical experiment.

[1] https://www.springer.com/gp/about-springer/media/press-relea...

Personally I think the assumption that science has figured it out is going to turn out to be nonsense. Science thought that in the nineteenth century right before discovery of general relativity and quantum mechanics.

Personally until we've figured out things like consiousness and dark matter/inflation etc I think the null hypothesis should be that there is unexplained stuff happening and thus it's likely advanced civilizations use something other than electromagnetic waves, just like we don't use smoke signals or fire beacons much for communication anymore.

>does anyone know if there is any theory to support the idea that sufficiently advanced civilizations rely on something other than radio waves or light to perform communications?

At a scienctific level no, but in science fiction you have devices like the 'subspace ansible' and similar things that allow FTL communications by using some sort of currently-undiscovered 'subspace'.

I actually remember in the mid 90's seeing, in the Weekly World News (a sensational tabloid for those unfamiliar) or its primary competitor at the time, mention of a intelligence agency that had laptop like devices that allowed for real-time encrypted communication anywhere on the world which was likely a spin on this idea (IIRC it was suggesting some sort of quantum entanglement where doing something to one would instantly cause the same to happen on the 'paired' device so you'd just type on one and it would instantly appear on the display of the other).

There's no valid reason to think something like this isn't possible, or even plausible. We didn't discover infrared until 1800, x-rays and radio until 1895.

There could very well NOT be anything that would allow for FTL/real-time communication over any distance but then again there could be. There could very well be some sort of radiation or similar particle that we've yet to discover too which might be the preferred means of communication for an advanced enough civilization.

Look how far computers have come since I was born in 1985. Look at other technologies like genome sequencing, the human genome project took 13 years and cost many millions but now you can do whole genome sequencing commercially with an 18 hour turnaround and hire your own whole genome sequencing out for 500$ with a 10-12 week turnaround. I know these examples don't compare but what I'm getting at is we are barely a technological species and who knows what possibilities exist for us.

For anyone interested in this or related topics I highly, highly recommend the series of 100+ videos in Science and Futurism with Isaac Arthur ("SFIA") [1].

Relevant to this topic:

- Fermi Paradox series (15 videos) [2]

- Advanced Civilizations (19 videos) [3]

- Alien Civilizations (10 videos) [4]

Of particular relevance is the Kardashev scale [5]. The basic idea is this: unless something catastrophic happens, humanity is destined to become a Kardashev-2 ("K2") civilization without a blink of a cosmic eye (measured in thousands of years). Since the timeline from sentience to K2 is so short (cosmologically speaking) it seems pretty unlikely there are other spacefaring civilizations in our galaxy.

It's worth noting that the scale of such a civilization is so immense and what it is capable of with access to that much energy and resources tends to debunk a lot of ideas that come out of a search for explanations to the Fermi paradox.

For example, there is the idea that civilizations might "hide" and would not be detectable. Such an effort would be futile vs a K2 civilization however.

I mention this because there is the idea that aliens might not use radio technology. Doing so wouldn't keep you hidden from a K2 civilization so there's no point in trying. And I find this a compelling line of reasoning.

[1]: https://www.youtube.com/channel/UCZFipeZtQM5CKUjx6grh54g

[2]: https://www.youtube.com/playlist?list=PLIIOUpOge0LulClL2dHXh...

[3]: https://www.youtube.com/playlist?list=PLIIOUpOge0Ls3WMYP_2Fp...

[4]: https://www.youtube.com/playlist?list=PLIIOUpOge0Lu97HzMt_BJ...

[5]: https://www.youtube.com/watch?v=dArpj_VxxuQ

My favorite channel on youtube. Couldn't reccommend it enough.

Isaac Arthur is my absolute favorite. Every Saturday morning after I make my coffee, I sit down and am enthralled by this week's video.

I made this comment earlier but to me the most logical explanation to the Fermi paradox is the vast amount of time between existence of any 2 civilizations. While many could in theory exist in the same Galaxy, the cosmic scale makes it unlikely that any two will ever share the same time scale, thus making any possibility of contact unlikely.

The argument against this is that a civilization that colonises more than two planets(which a K2 civ could do) has astronomically low chances of getting wiped out, so any that get there first should probably still exist. Which means the time gulf isn't really the problem.

So this is several theories wrapped into one. The Dyson Dilemma (meaning Dyson spheres seem inevitable for civilizations with no more tech than we’re expected to have this century) reduces this idea to civilizations tend to destroy themselves.

It’s important to remember that we are not arguing if some if not many or even most civilizations destroy themselves. For this to explain the Fermi Paradox you’re arguing that basically all do and there are lots of problems with that argument.

Dyson spheres are not subtle. We can say a high degree of certa8nty that no Dyson spheres have emerged within a billion or so light years of us where light has had time to reach us or we would’ve detected them.

Say 10,000 civilizations rose up within that sphere. Even if 9,999 of them destroyed themselves we would detect that 1 tha didn’t.

We have been able to derive an immense amount of information about our universe from observations and probes but we're still incredibly ignorant. We can't even determine whether or not there might be a substantial dark body (several times the size of Earth) orbiting within our own solar system. That hypothesis is being used to try to explain other things that remain otherwise inplexicable even within our own 'little' solar system. Grand claims about being able to detect dyson spheres with a billion light years are just silly.

And even when we do detect things reminiscent of what might be a dyson sphere there is a very logical and reasonable desire to not accept this and instead look for natural explanations. For instance KIC 8462852 was never fully explained and its dimming continues to this day. The only thing that stands out against it being an 'obvious' dyson sphere is the lack of ambient infrared, which we can attribute to a variety of factors, not the least of which being the all-encompassing 'technology we don't yet know'. But we don't do this precisely because when you start going down this road you can attribute basically anything to 'aliens' in the same way a religious person might attribute otherwise explainable events to a god. The point of this being that unless a LGM walks up to us and says hi, we're not going to attribute anything, seriously, to their existence.

You've gotta keep relativity in mind here. If a species can develop a means of simply traveling at roughly 1g acceleration indefinitely, they will become -in terms of time- practically immortal. A single human can travel literally billions of light years in a single lifetime by continuing to accelerate at 1g for years at a time. Here [1] is a calculator to determine how long it would take to travel a given distance at a given acceleration. A common misunderstanding is the difference between observed mass increases and perceived. Your mass does not increase as you approach the speed of light relative to something else. But your observed mass does.

Anyhow, the point here is that once a species reaches this level of technology, if it's possible, they will start to move beyond anything like the borders of time as we understand them.

In my opinion, the most simple and probable explanation is technology (we don't know what's out there), but that's closely followed by the terrifying great filter being complete and unadulterated pleasure. As lives become easier and more pleasurable, the inherent drive towards procreation becomes less and less of a factor. If that reaches below a certain point, that's lights out for a species. Create a guaranteed means of subsistence on a planet, perhaps entirely automated, and now create a technology that becomes more inherently enjoyable and rewarding than procreation itself. Congrats you evil villain, you've destroyed your species in a far more effective way than any weapon ever could. Society goes out not with a bang, but also not with a whimper; they go out with a moan of pleasure.

[1] - http://convertalot.com/relativistic_star_ship_calculator.htm...

This is basically what I think. Why traverse the universe when you can upload your brains into a matrix type simulation and place your hardware in orbit around a brown dwarf and then live basically forever. No one will ever find you.

One problem with things like this is the arrogance of the present. We had no idea that electromagnetic energy even existed until the later half of the 19th century. Even though it had been observed for centuries that lightning strikes could screw with a compass needle, we somehow never managed to put two and two together. Kind of funny in hindsight. Consequently all of our predictions for the future were cast through this lens. So their ideas of futurism was limited to things such as undersea exploration, flying machines, and ideas like covering an entire city in a roof so you wouldn't get wet while walking about.

Now we take electromagnetism for granted and can observe it everywhere, as it has always been. Yet the problem with this is that now, in order to have any meaningful discussion of the things of which you're speaking, you have to make the very questionable assumption that there will no longer be similarly revolutionary forces we will discover in the future. And so there comes a question of weighting that. What are the odds of that being true?

Our species' entire basis of knowledge is formed, almost exclusively, around observations based on one planet, in one solar system, in one galaxy. Everything else is just reasoning based on incredibly coarse observations of everything else. I think the idea that that we're even remotely close to unlocking the true nature of our universe is not really logical by any measurement other than 'well we're trying really hard and haven't been able to make that next step yet' which has, of course, been true throughout our species entire existence -- until that next step is invariably made. The increasing difficulty does not indicate anything like evidence of approaching an end to revolutionary discovery itself. Yet if we're not at the end then any meaningful big picture or very long term predictions are going to serve as little more than the butt of jokes for those with the opportunity to read such predictions from the future.

The point use that we don't need to assume any new physics or assume any new technology beyond what is considered highly likely for the next century to view Dyson spheres as admission inevitable. We don't even need to assume fusion.

New technologies exacerbate this problem rather than solve it. As do new physics. In fact Isaac mentioned multiple times that the inability the apparent absence of evidence of advanced civilizations is the best evidence for there not being FTL travel or communication (as just one example).

So while i can agree we don't know everything I'm not sure why it matters.

This is like in times past a people believing that they could detect any other intelligence by seeing the smokes from their fires. After all how else would they cook their food or create light to see in the dark? A dyson sphere isn't some profound insight into the universe. It's a relatively straight forward idea once we achieve the understanding that we can capture EM energy and convert it into other usable forms of energy. Of course before that revolutionary discovery or EM utilization it's something that would seem completely nonsensical.

I remember running SETI @ Home on my 300 MHz Gateway and watching the pretty graphs as if I was a real life alien spaceship pilot. It's funny to hear that it's actually a real thing (I knew it was real, but when I saw the size of the radio dish in the image, it's REALLY real)

Its the Greenbank telescope in West Virginia. I don't think its particularly associated with SETI.

The telescope is available on a rental basis. People just schedule it to point it wherever.

> I don't think its particularly associated with SETI.

That depends on what you mean by "associated". It's not associated directly with SETI the institute, but it was the site of the first systematic/scientific search (and false positive) for extra-terrestrial intelligence lead by Frank Drake. It is also the place where The Order of the Dolphin (Drake, Carl Sagan, Otto Struve, et al.) met and developed the Drake Equation.

The one in the picture is the 100m dish. Frank Drake used the 25m dish. Just being nitpicky, I get your point.

https://en.wikipedia.org/wiki/Drake_equation#History

The telescope there is amazing. It's worth a visit, they have a visitor's center and tours. I was there for the 50th anniversary celebration, in 2006, and want to go back some day.

Same on my 100 MHz Apricot. I like to think it helped. One thing that used to bug me is I wondered how much CPU time was being spent on rendering those graphs locally.

Underlying source : http://seti.berkeley.edu/frb-machine/

and paper : http://blpd0.ssl.berkeley.edu/frb-machine/CNNFRB_eprint.pdf

> The high degree of rotation of the nearly 100 percent polarized radio bursts is unusual, and has only been seen in radio emissions from the extreme magnetic environments around massive black holes, such as those at the centers of galaxies. The Dutch and Breakthrough Listen teams suggest that the fast radio bursts may come from a highly magnetized rotating neutron star – a magnetar – in the vicinity of a massive black hole that is still growing as gas and dust fall into it.
The short bursts, which range from 30 microseconds to 9 milliseconds in duration, indicate that the source could be as small as 10 kilometers across – the typical size of a neutron star.

Other possible sources are a magnetar interacting with the nebula of material shed when the original star exploded to produce the magnetar; or interactions with the highly magnetized wind from a rotating neutron star, or pulsar. [0]

Do any terrestrial sources create polarized radio waves? Would polarization help beamforming or other range-extending techniques?

[0]http://news.berkeley.edu/2018/01/10/seti-project-homes-in-on...

I'm certainly no expert, but the Wikipedia article on the subject says this:

> All radio (and microwave) antennas used for transmitting or receiving are intrinsically polarized. They transmit in (or receive signals from) a particular polarization, being totally insensitive to the opposite polarization; in certain cases that polarization is a function of direction. Most antennas are nominally linearly polarized, but elliptical and circular polarization is a possibility. As is the convention in optics, the "polarization" of a radio wave is understood to refer to the polarization of its electric field, with the magnetic field being at a 90 degree rotation with respect to it for a linearly polarized wave.

https://en.wikipedia.org/wiki/Polarization_(waves)#Radio_tra...

So it's less that it helps, and more that it's inevitable.

I've converted series of those images to audio, it's obviously swipes and trills only. I wish I could get my hands on higher resolution images to get a drop of a real alien dubstep, not some cheap microwave oven blues.

Could you post a soundcloud link or something? I’d be interested to hear what you’ve got.

Uploaded.

SoundCloud: https://soundcloud.com/xca8biolusw4/sets/seti-space-noise-ma...

Conversion script used: https://gist.github.com/ptytb/6eade153de6f54dbc0fc1fc0d46993...

no way would an Alien specie able of sending signals of such strength would send uncompressed / unpreprocessed audio. it is more likely that they would send perfectly compressed data that would appear indistinguishable from noise to us, as this is what optimally compressed information looks like

Inspired by NASA?

https://www.stufftoblowyourmind.com/blogs/symphonies-of-the-...

>For instance, the probes picked up the interaction of solar wind on the planets magnetospheres, which releases ionic particles with an audible vibration frequency. Essentially, we can then translate these waves into sound waves and put them on an album.

https://archive.org/details/SymphoniesOfThePlanets2

https://archive.org/details/SymphoniesOfThePlanets3

Wow, this seems really exciting. This could be huge!

Narrator: It wasn't.

It is exciting because we can't explain it yet. That makes it interesting and worthy of study.

>> This could be huge!

Don't get me wrong, I appreciate the humor and understand how the media tends to over hype any news that could potentially excite people interested in the discovery of little green men, but I never felt that this particular article was doing that.

Ok, but the point isn't little green men -- it's that SETI is now using AI and a convolutional neural network. Not that AI and ML isn't also a victim of media hype...

I felt like this particular article was almost bizarrely moderate in its tone. It managed to talk about ML and a new seti discovery in a balanced manner, discussing both the optimistic and realistic takes. I guess I'm just so used to modern headline writing that I'm pleasantly surprised when someone doesn't publish "Artificial Intelligence finds aliens." :)

>noisy galaxy 3 billion miles away

that's only 0.00051 of a light year, or a few light hours away.. either me or them has a big math problem.

Yes, 3 billion miles is closer than Pluto.

The press release says 3 billion light years. Probably just a mistake at TC

PR: https://breakthroughinitiatives.org/news/22

I wonder why many people visualize aliens to be entities with flesh or something else like how species (that move or grow) on earth. I think aliens can also be in the form of new elements, rocks, gases, waves, or some entity which is beyond the ability of 5 senses of humans to perceive. Currently we use other methods to transform perception of entities so that humans can see/feel/hear/understand. But the devices we build for this purpose are built using earth elements. It could also be probable that earth might not be having those elements which are required to give humans the ability to perceive other entities.

Depending on who you read, life could be quantum wave functions flying around the universe, or even dark-matter "birds" slowly tearing suns apart.

I may read too much sci fi.

Yes, the fight between Baryonic matter and Dark matter does promise to be quite the show: https://en.wikipedia.org/wiki/Xeelee_Sequence

Well, chemistry has some pretty good evidence on which elements do and can exist. I don't think we'll be seeing unknown elements (sorry Mass Effect) any time soon.

And if they exist beyond what physics can currently detect, then the point is sorta moot.

Not unknown periodic table elements, but new minerals, possibly formed in conditions not found in Earth, yeah

Chemistry would suggest we've found all stable naturally occurring elements too.

BUT I will say that there is extremely good evidence that there are plenty of unknown elements (I'd argue that every chemist agrees). Well, more accurately, elements we haven't created. Feynman says the limit is 137, but others think it is higher (relativistic limits). The thing is most of these are unlikely to be stable, though there are some predictions for stability in the 120's.

But to be life, they would need to be stable. And it would be EXTREMELY odd for life to be made from non common and non naturally occurring elements. Even more odd to be from unstable ones.

It's exceedingly likely that any new elements we discover will have half lives fractions of a second and not available anywhere in the universe other than the labs of civilizations at least as advanced as us. So there's almost no possibility that they play any role in alien life.

Well there are predictions of islands of stability[0] in the 120's (and further) because magic numbers[1]. But no one agrees on how stable those are (milliseconds or MUCH longer). And I do want to mention that I did suggest that these elements would need to be created in labs.

>> Chemistry would suggest we've found all stable naturally occurring elements too.

Because these elements are trans-uranium. IE: Man made.

> So there's almost no possibility that they play any role in alien life.

>> But to be life, they would need to be stable. And it would be EXTREMELY odd for life to be made from non common and non naturally occurring elements. Even more odd to be from unstable ones.

Read "odd" as "highly unlikely and unexpected".

I'm not really sure where we're in disagreement. Except for the island of stability part. But that's why I said

>> most of these are unlikely to be stable, though there are some predictions for stability

We don't know if they are stable or not yet. Because we haven't made them. And I am making ZERO claims that there are. But I am making claims that there are predictions of stability. Which is trivially verifiable.

[0] https://en.wikipedia.org/wiki/Island_of_stability

[1] https://en.wikipedia.org/wiki/Magic_number_(physics)

I completely agree. It's all we know so we don't think about it as humans but we have very limited sensory organs. We can only see like 0.0035% of the light spectrum, out sense of smell is nothing compared to what a dog can smell, and we can't even sense magnetism!

I imagine watching humans do technology from an aliens perspective is like us watching a chimpanzee use an iphone.

Actually we can see 100% of the em spectrum, we have tools and instruments, in fact that is what separates us from the chimpanzees you mention. Give your species a little credit.

Like roentgenium and basalt might be aliens?

Because carbon has the richest chemistry, making it the most likely basis for life:

https://blogs.scientificamerican.com/lab-rat/shine-on-you-cr...

I think there is more to life than just flesh and senses. Fundamentally, what makes living organisms "living" is the DNA (in primordial soup, it was RNA). Self-replicating systems lead to evolution almost magically... spontaneous processes (that minimize energy and are driven by thermodynamic imbalance) tend to create "competition" as they use up resources. The ones that make barriers or membranes, can protect the resources and end up replicating in larger numbers or faster.

We know that Carbon is essential in creating these self replicating entities. Its abundance is also known in the universe. So, it is not so unrealistic to presume that aliens won't be something that we can see on earth. I am curious of the differences of the forms of life that can originate though.

Imagine if we rerun 2 billion years of evolution again with a different initial conditions. Surely, we'd have different forms. Contrarily, eyes have evolved independently in many organisms over a dozen times. So, there is some commonality there. Just like the eye, there are many similar biological processes that evolve independently (arteries/veins, neuron, heart for circulation/extraction, ceramic structural components/bones, etc.)

I used to think about the same question that you are also wondering but the deeper you go down this rabbit hole, you are realize the importance of why things in living beings are the way they are. They're solutions (however imperfect) to an evolutionary problem.

Why would DNA be essential? Why limit "life" to just carbon-based lifeforms?

It could be another self-replicating entity. It doesn't have to be DNA. But self-replication is the __basis__ for evolution of life. Sure, it could be made from other elements...but why wonder if other elements can create self-replicating entities when you can measure the amount of Carbon in the galaxy...right from here on earth! Carbon is more abundant than say Strontium. Carbon is created inside a star, Strontium is created through Supernovae explosions.

Also, Carbon can form 4 covalent bonds more easily than Si (same family). Si can form 4 covalent bonds but they're weaker than Carbon due to the distance from the nucleus. I am sure someone more familiar with Chemistry can chime in, but Carbon is a special element in the Universe.

Indeed carbon is special in this regards it's also produced in star fusion and space is filled with organic material because carbon, oxygen and hydrogen are abundant.

Also the main reason why silicon is worse is because of catenation, which carbon is much better suited for: https://en.wikipedia.org/wiki/Catenation

Thanks for adding to the discussion. I learned something new.

You were right it's because of the covalent bonds formed, however the biggest difference seems to be not in how these are formed with other elements but how carbon is essentially optimal at bonding with itself creating huge chains.

This property is why there are so many different and interesting forms of elemental carbon.

These chains are the scaffolding for all biochemistry both because they are very stable and also because they have very interesting properties.

Chains can be either open or closed depending on various factors such as charge, temperature and other forces that play on molecular levels allows you to play with that geometry.

Having strong chain bonds not only builds stable chains but it also build chains that can change their state while remaining intact and biochemistry heavily relies on the ability to change the geometry of complex molecules without breaking them apart.

Because of physics.

> Contrarily, eyes have evolved independently in many organisms over a dozen times.

I'd argue that this is because we all have the sun in common. On a planet that orbits a star with a different spectrum or a planet that has a different atmospheric makeup, "vision" might look very different to what we're used to.

Life may also come in the form of a group of "artificial" robots that can mine and manufacture copies of themselves, with AI that can learn and teach each other.

Such "beings" (and indeed they should be indistinguishable from "natural" beings given a few hundred years) wouldn't need to evolve from scratch, so they don't necessarily have to be mostly built from basic elements like carbon.

We like to start small, then think bigger later

Ghost..is the word you are looking for.

Good point. If you haven’t read “They’re Made out of Meat”, you’ll find this short story very amusing:

http://www.mit.edu/people/dpolicar/writing/prose/text/thinki...

There's a short film adaptation of this as well: https://www.youtube.com/watch?v=7tScAyNaRdQ

Michio Kaku certainly argues for existence of aliens in the higher dimensions than our own-4th dimension has time element, all the way up to the 11th.

In fact he argues that it's possible that these higher dimensional beings figured out how to travel between universes (if you follow the multi-verse theory) by heating up to an insane temperature point where it rips a hole in the space-time fabric, allowing for the said civilization to continue living in another universe where it isn't collapsing.

To me the Minot airbase incident is the most telling based on all 20 something individuals that witnessed the same events where light orb like things deactivated the nuclear silos.

This suggests that the nuclear tests basically triggered a radar somewhere deep in space by said advanced civilization, then suddenly you have a spike in UFO sightings.

I think this scared a lot of people at the top, because their power base is directly threatened by an advanced adversary that has technologies far beyond your own, want to keep hush hush so they mix lot of hoaxes to make it impossible to distinguish real from fiction (a classic disinformation strategy with tall tale markings of tradecraft also used by Soviets).

What's even more strange are both USSR and US encounters with UFOs and the same type of hush hush, namely the Phobos satellite which was 'decomissioned' by a similar looking object found during the initial Apollo moon landings, which is riddled with censorship, including what appears to be unnatural and regular structures and objects you can observe with a powerful telescope (check out https://youtu.be/3xiJnDuVOFA?t=2m12s)

Just watch Unacknowledged on Netflix....it was frankly eye opening.

say what you will but the fact that US Navy released the UFO video captured by F-18 IR radar, the announcement of a "Space Force", it's all obvious that the next bogeyman won't be communists or terrorists but extra terrestrials....this is the ultimate logical conclusion one can make based on the following core belief that tests one's affinity for trust in higher institutions formed by humans.

We can detect elements in other star systems. Earth elements are pretty standard, it turns out. Interesting idea though :)

So, aren't we sending out radio signals in a spiral as the planet rotates that would be massively spread out over a distance of 3 billion light years? If I were broadcasting something into space constantly some alien civilization would only be exposed to perhaps a very short portion of the signal until Earth had fully rotated again and my signal lined up perfectly to their planet again.

Yes we are sending radio light out, but it certainly has not traveled 3 billion light years. Also, our weak transmission would be nearly invisible. FRBs are interesting because they are super high-energy bursts over short time durations.

Indeed, hell, our earliest broadcasts have barely made it past the closest star systems.

If we can control the amount of energy as these broadcasts, we'd basically be gods for all intents and purposes.

EM waves are spherical in nature (analogous to ripples in a pond) rather than directional. So the rotation of the earth wouldn't significantly affect the strength/reception of the signal by a distant planet. The bigger factors would be signal degradation because distance and other kinds of interference.

Well, that's true, but that is why we use dishes to direct the signal:

https://en.m.wikipedia.org/wiki/Parabolic_antenna

I think we generally believe that the dishes are used just for receivers but they are also used in directing transmitters.

In fact, there are also heavy regulations for high-speed long distance directed microwave antennas to not spread the signal too broadly:

https://www.fcc.gov/Bureaus/Engineering_Technology/Orders/19...

"EM waves are spherical in nature (analogous to ripples in a pond) rather than directional."

No, they aren't. This is an approximation taught to you in high school to make certain problems more tractable. You've got at least two methods of generating non-spherically-expanding EM waves sitting in your pocket right now; neither your phone's screen nor its flashlight are perfectly spherical in emission. This is trivially observable by the fact that the orientation of the phone impacts your perception of its brightness.

It's true that you can't make a "fully" directional EM wave with no spread whatsoever, but you can make it arbitrarily small with engineering effort, and they're trivially not spherical.

Regardless of the shape of the beam pattern, the signal strength scales with distance equally as with a sphere, which is the inverse square law.

I don't think anything from Earth will be detectable beyond more than a few light years.

Any EM waves created to be highly directional at earth-scale distances quickly lose that directionality at galactic-scale distances. Doesn't have to be spherical, but it will quickly spread out over distances much greater than typical solar system sizes.

Not true. See beam divergence:

  https://en.wikipedia.org/wiki/Gaussian_beam

> aren't we sending out radio signals in a spiral as the planet rotates that would be massively spread out over a distance of 3 billion light years?

We started sending radio signals in an appreciable amount somewhere around the 1920-1930s, and have since made our radios so efficient (also with the help of satellites) that by now they are basically too weak to be realistically noticable by distant civilizations.

Given that we started about 100 years ago, those radio signals only traveled 100 light years (enough to reach quite a few solar systems, but only about 0.1% of the radius of the milky way).

We don't know quite how good alien civilizations are at signal processing, but beyond 1000 light years or so it will be seriously hard to seperate our broadcasts from random noise. So not quite 3 billion light years.

For some clarity, the signals we have been broadcasting (mostly things like TV and radio) are MUCH weaker than the radio waves that the sun produces in the same spectrum. So our signals do get "washed out".

"Seventy-two new “fast radio bursts” from a mysteriously noisy galaxy 3 billion miles away"

Wait, what? I thought space is big. Really big. This mysterious distant galaxy is practically in our backyard.

Should be 3 billion light years according to other articles.

Not just practically, I would say 3 billion miles away puts it firmly on top of us.

About as close as Pluto. No wonder it can't be a planet.

Message probably says: "Get us in touch with your Plutocrats".

Our plutocrats don't take kindly to illegal alien aliens.

Three billion miles is roughly the distance to Neptune. So, yeah.

For reference, that's closer than Pluto is (normally) to the Earth.

Other sources all say "3 billion light years", which seems more accurate and believable.

I'd just like to address a pet peeve by saying that the Fermi Paradox is dumb.

It's often thrown around as a low-effort dismissal as if it were a fundamental law that must be fulfilled for extraterrestrial intelligence to be considered.

It's a relic of a less-informed era when space was filled with aether and green-skinned humanoids were fancied to inhabit the Moon and Mars, and flying vehicles were expected to be our primary mode of transportation by 20 years ago.

An extreme simplification that basically says "If X then Y MUST follow. If no Y then no X."

——

We have long had the technology to establish a permanent presence on the Moon, why haven’t we done so by now?

We have the tech to put men on Mars, why are we not even planning to do that already?

We can build photovoltaic cells, why isn't the Earth covered in them yet?

There are still uncontacted tribes on this very planet untouched by modern civilization, why haven't we uplifted our own species yet?

I guess we don’t exist either.

The fermi paradox works on a different timescale than the points you bring up, which is exactly why it keeps being brought up.

Our civilization has existed for only several thousand years. That is nothing on the cosmological scale. The fermi paradox asks why, when looking at the age of the universe, there is no visible (to our level of technology) trace of other civilizations. Even when expanding at a crawl, a civilization having had a million of years to do so should have reached every corner of our galaxy.

The fermi paradox is simply a question: why? Suggestions, like a civilization uploading itself to some sort super computer to experience eternal life, are answers to the fermi paradox. But they do not invalidate it.

> a civilization having had a million of years to do so should have reached every corner of our galaxy.

Why? Why indeed.

Why should they? Why is it desirable to do so?

Why haven’t we done many of the things that we technically could have done in our timescale by now?

“They should have reached every corner of our galaxy” relies on at least the follow assumptions:

• That it is desirable to them.

• That their ability to reproduce/replicate can keep up with their technology to expand.

• That their presence on every planet they colonize lasts indefinitely.

• That there is no force—natural, adversarial or internal—that counters unrestricted expansion.

• That they even can expand in all directions. (Again, consider our own solar system and how useless, hostile, uneconomic or unstrategic some of the planets in it would be to humans.)

• Following on the previous point, that they’re dumb enough to spread themselves thin by colonizing every sub-optimal planet, instead of cherry-picking the planets which are best suited for them or, indeed, constructing their own artificial habitats in space.

• That we have the ability to detect all signs of alien presence on all stars and all planets, including any possible artificial worlds and rogue planets.

• That we have the ability to detect all PAST alien presence: An species may have already colonized this galaxy once, but thanks to the aforementioned timescales we may have missed running into them by a few million years, like we missed the dinosaurs on our own planet.

——

The Fermi Paradox is a flawed premise that itself needs to answer many other “why”s before its “why” can be answered.

“Intelligent Life -> [Long enough timespan] -> Intelligent Life on every planet around every star.”

A -> [B] -> C, where [B] makes a ridiculous amount of assumptions, then takes the absence of C to invalidate the possibility of A.

The Fermi Paradox, like any good paradox, isn’t a “premise;” it’s a tool to reveal premises. Your thoughtful comment on many possible explanations for why we might not see aliens is exactly what I like about the Fermi Paradox - it makes you think.

My issue is with when it's still reverently referred to as a serious argument against the possibility of extraterrestrial intelligence, even after we have had enough time to see that an intelligent species doesn't necessarily expand to other worlds just because it can.

~ 100TB an hour of data.

I’m guessing it doesn’t compress well. Do they write that to disk or filter it in memory and only pass on a subset?

If it was compressible, that would mean there was a repeating pattern. The whole point is that the data is extremely noisy, so finding a pattern is difficult.

I imagine a lot of sensors are detecting the same silence or non-zero EM signal most of the time (when adjusted to be as-if they were pointed in the same direction, anyway) and differences are the rarity.

So finding SETI is all about finding compressible data ?

Actually, yes. There's a deep connection between the compressibility and predictability of things. But we're not good at learning the complex distributions needed for these sorts of things - there's a long standing competition for natural language compression, the idea being if you can do that perfectly you basically have human level semantic understanding.

400TB in 5hr??? So in 18000 sec (5hr×60min×60sec) they saved 409600 GB... which roughly is a transfer speed of 22.7GB/sec. I'm wondering what type of SSD raid they've got :-)

I'm sure the data is coming in from multiple sources and being stored on high capacity tape archives or something, if it's not just being thrown away at some point after analysis is complete.

Not possible, write bandwidth of tape is not very high.

My guess is they have a cabinet / 42U worth of HDD arrays, by the numbers they need ~ 176Gbps write bandwidth which is totally possible even in half a cabinet.

400TB worth of SSDs @ 176Gbps write bandwidth is also very possible, would be ~ 4U expect but extremely expensive.

" from a mysteriously noisy galaxy 3 billion miles away"

That is good news, that galaxy is close enough to visit;) :

https://www.google.com/search?source=hp&q=3+billion+miles+to...

https://voyager.jpl.nasa.gov/mission/status/

I am glad the information was not presented in a sensational way. I find Fast Radio Bursts really interesting. They have been discussed on HN many times. For those interested see: https://hn.algolia.com/?query=fast%20radio%20burst&sort=byPo...

It's cool that a single dish telescope discovered so many FRB within a short time but the fact that it was done with SETI time on GBT doesn't make FRB as a concept a SETI thing. It's an unexplained thing but broadband radio bursts aren't exactly uncommon in nature. FRB are just really far away.

The swept curve as shown in the spectrograms is probably because of distance to the signal and frequency dispersion due to charges along the line of sight. FRB are originally broadband pulses that distort in the medium getting here.

It looks like these ones are pretty simple quick burst. The latest discovered by the UTMOST all-sky interferometer recently had a complex bursty structure over time, http://astronomy.swin.edu.au/research/utmost/?p=1475

Instruments like UTMOST and other all-sky digital processed arrays (like SKA and children) should get some every hour once everything is running and optimized.

> 3 Billion miles

That is ridiculously close. For reference, the distance between sun and earth is about 150 Million miles.

The reporter probably assumed light years are a measure of time and "fixed" it.

From context, I 'm pretty sure its light-years, not miles, and this was a typo. The curvature of the pulses in the frequency domain implies that there's lots of ionized gas between the us and the source. Lower frequencies are delayed relative to higher frequencies.

Also, "mysteriously noisy galaxy 3 billion miles away" (emphasis mine).

Lets hope that they allready checked the microwave oven

Kmetan is serious. Half of the first detections of FRBs were traced to a microwave oven at Parkes Observatory.

What amuses me is the fact that we are so obsessed with finding civilizations that have an equal or superior level of technology than we do... If such civilization does exists, and if they are anything like us... Our history show us things will NOT end well for us!

The more advanced civilization will eventually (always...) conquer the less advanced civilization when in need (or desire...) for resources.

It is like if a deer were obsessed to find the hunter that will put its life to an end...

If the question we are trying to solve is "Are we alone?" we have better try to look for "less advanced" forms of life, like marine animals or something like that...

Otherwise we will get the kind of reply we are not looking for... IMHO

I sometimes imagine a species which is to us like we are to cockroaches...

> The more advanced civilization will eventually (always...) conquer the less advanced civilization when in need (or desire...) for resources.

I think this doesn't translate so directly into space. If they are thousands of light years away, then they will have plenty of other planets nearby to harvest for resources.

Especially while the planets aren't the first place you go to harvest resources.

It all depends on what sort of resources they are looking for, no one is crossing light years to come steal water from us, when there are other planets that have water (perhaps as ice) and would be undefended. However if they needed territory and the earth had an environment that was hospitable to them then yes they might very well travel light years to invade.

and they will probably (or at least hopefully) be more enlightened.

Perhaps they are trying to attract contact from less advanced species to find planets supporting life, so they can have more meat in their diet...

Resources are not solely iron ore etc.

https://en.wikipedia.org/wiki/Fermi_paradox

Liu Cixin does a great job exploring these ramifications in his "Three Body" trilogy.

Please let it be aliens

I'm interested in aliens especially because of biological curiosity. I wonder how did their evolution happen, what unique futures their species developed, from what sort of creatures they evolved (if they're primate-like too, that would be very weird), do they have emotions like humans, why did their brain evolve so large?

Please let it not be aliens.

The background radiation is actually the universal communication band broadcasting the entire knowledge of every civilization that has ever existed but sadly it is encrypted so appears to be random.

72 new bursts, on top of 21 already identified, in five hours of data. Total of 93 bursts in five hours, for an average of one every 3 minutes 14 seconds. That's... rather surprising.

It was a 5 hour session, but all of the bursts were discovered in the same 1 hour period.

>Initial “standard” algorithms identified 21 FRBs, all happening in one hour’s worth of the observations...Sure enough, the machine learning model picked out 72 more FRBs in the same period.

If it is actually an average of one every 3 minutes 14.159265359 seconds ... now you've got something.

The length of the minute and second are arbitrary.

Dream-killer. :P

You mean not every civilization chooses to make their unit of time multiples of 9,192,631,770 cesium-133 oscillations? /s

Plus, if they don't use Tau by convention, they aren't even worth discovering in the first place.

Now you've come full circle. You'll next be suggesting we use IBM 360 computers. http://ibmsystemsmag.com/mainframe/trends/z-os/complete_360/

That would be meaningless. Pi is 3.14159. But 3 minutes and 14 seconds is 3.23333 minutes. There's no special relationship between the numbers "3" and "14" in different arbitrary bases...

Using machine learning to anaylze mystery signals reminds me of Stanisław Lem's novel His Master's Voice (1968). It's a fictional memoir of a mathematician working on a Manhattan Project-like project to analyze a signal from space. The book is like a cross between Contact and Catch-22.

https://en.wikipedia.org/wiki/His_Master's_Voice_(novel)

Can we please stop calling FRBs mysterious signals when we already have name for them. It's not something new it's FRB. They set out to find FRBs and they found FRBs.

People are so quick to classify anything that can't be explained immediately as extraterrestrials. I would bet a lot of money that this has nothing to do with extraterrestrials only because after so many years there is no proof that such exist.

Come on everyone get back into reality and look for the true answer. A true scientist tries to disprove his/her theory until there can be no other answer as opposed to picking the first theory and going with it.

There is some evidence for it: https://en.wikipedia.org/wiki/2006_O%27Hare_International_Ai...

UFO does not equal extraterrestrial. It's an acronym for an unidentified flying object. Also, for many years the air force promoted the UFO idea as a way to cover their aircraft research.

https://en.wikipedia.org/wiki/UFO_conspiracy_theory

oops wrong link

Here's the right one:

https://www.usnews.com/opinion/articles/2010/09/16/the-truth...

If you haven’t read “Three Body Problem” - warning spoiler alert - the premise was mind blowing to me - that the reason aliens aren’t broadcasting signals is that more mature spacefaring societies use those signals as targeting vectors! Eg aliens aren’t interested in making contact, and our efforts to broadcast our location could be inviting our ruin.

That's exactly where my mind went when I read the link... whatever we do, don't answer the signal :-)

We'd be safe for 3 billion years, probably. Also I don't think we have the technology to answer that call (can radio waves sent by humans be visible after traveling 3 billion lightyears?)

Haha sounds like a movie preview.

Possible, but not something I'm worried about. Those "mature" societies are still limited to the speed of light, they would have to be willing to wait out an average trip of thousands of years just to wipe out new civilizations in our galaxy - assuming the new civilization survives that long.

Yes! The bursts from FRB 121102 took 3 billion years to reach earth.

> Those "mature" societies are still limited to the speed of light,

Isn't that just an assumption though? As short as 1000 years ago traveling to the moon seemed impossible.

FTL would break a lot of other evidence-based findings in a way that lunar travel did not.

Correct me if I'm wrong but my understanding is that newer theories of physics do not exactly overthrow older ones. The conservation of energy for example still holds true for everything that Newton observed it at but for in other situations it falls apart. So E=mc^2 is an extension of the original law. Same thing with the theories of relativity, they explain Newtons observations as a subsection of a bigger system.

Afaik nothing in current physics prevents FTL from being logically possible. Nothing predicts it either but that doesn't mean it's impossible.

Special relativity says it's not possible.

General relativity says that maybe you can get something equivalent by taking non-linear paths through space-time but those sorts of things require very radical types of matter to avoid collapsing into a black hole. And realistically, it's IMO very unlikely that these sorts of things would remain in a more complete (e.g. quantum) theory of gravity.

This is a well articulated point. You're right. My only counter might be something less articulate like "1000 years ago our understanding of physics/space/etc was incomplete." Possibly our understanding now is still incomplete.

With the technology in the "The Three-Body Problem", the aliens can monitor all the solar systems they like with sophons and then whack the dangerous ones with projectiles fired by the nearest space ship.

Not an assumption at all. All evidence seems to indicate that FTL travel is impossible. Also remember, you have to go way faster than that because everything in space is moving away from everything else. So really you have to go (faster than light + rate of expansion) = speed you need to go.

Also, its one thing to go the speed of the light, its another to slow down from it!

A mature civilization could probably perform a kinetic bombardment with masses accelerated to a significant value of c. There would be waiting, but there would be no need to travel here personally.

That said, I'm not particularly worried about it either. I suspect we will either have scientific value (independently evolve intelligence, which appears rare) or never pose a real threat to them, assuming learning curves remain exponential for civilizations.

To assume they are limited to the speed of light is like ants assuming that pheromones are the only method of navigation.

But ants can't build sensors to indirectly or more accurately observe other forms of communication, much less surmise about their existence in the first place. The complexity scale of intelligent life can't increase forever, and there's no reason to expect the ants:humans ratio to extend to humans:aliens. Whoever's out there is bound by the rules of this universe, just as we are.

> The complexity scale of intelligent life can't increase forever

What is the reasoning behind this statement?

> and there's no reason to expect the ants:humans ratio to extend to humans:aliens

the same is true of the inverse, being that there's no reason to expect that humans are at the limit of complexity, so for the purpose of speculation as to the likelihood of far more intelligent life, there's no good reason to exclude the possibility.

There's something called the Beckenstein bound[0] which is the higher bound on information density in a volume of space. That's probably the limit on complexity in life.

That said, we're several orders of magnitude away from that, and even we have a theoretical way of FTL travel[1].

[0] https://en.wikipedia.org/wiki/Bekenstein_bound [1] https://en.wikipedia.org/wiki/Alcubierre_drive

It is theorized that the laws of Physics can be different in different parts of the universe. Maybe elsewhere speed of light isn't an issue

If they are functionally immortal - and what sufficiently advanced species wouldn't make themselves immortal at first opportunity - thousands of years may not be a deterrent at all.

There's always things like the Alcubierre drive that circumvent the speed of light. Thousands of years isn't necessarily what is needed. It's just that they have to find out that there's someone here, which will need light from us to get there, and that might take thousands of years. Billions, probably.

That always seemed to me to be some particularly flawed reasoning. Any civilization advanced enough to be able to destroy another at cosmic scales is advanced enough to know that the universe will end some day, so there's no real virtue to killing off everyone who isn't you just so you can hoard all the resources until heat-death takes you.

Any civilization advanced enough to travel the distances in question has better things to do than pick on puny Terrans. It's like driving from California to Florida to shoot a squirrel.

Spoilers

The premise of the series is that the Universe is like a dark forest. A civilization is like a hunter wandering through a dark forest. Any sound is likely to first be met with a bullet and then curiosity. At galactic scales, by the time you first communicate with a civilisation, they might have advanced immensely from when you first detected them, and the slightest miscommunication could cause war at massive scales with high probabilities of losses on both sides, so you shoot at the first noise you hear with extremely low effort weaponry that will definitely kill an underdeveloped civilization.

The universe will end some day, but there's no point in letting your civilization end before that just because someone else decided to kill you when you were being generous.

To be clear though, I would rather be optimistic and say that civilizations can learn to work and live together, but the game theory explanation of this situation does make a lot of sense, and is backed up by a fair amount of historic data.

> The universe will end some day, but there's no point in letting your civilization end before that just because someone else decided to kill you when you were being generous.

But that's a philosophy of life that, taken to its logical conclusion, means that you should be doing your best to kill everyone that isn't you just in case, for instance, their progeny could hurt yours.

It is, frankly, very silly.

It's a common answer to the Fermi Paradox ("if life is likely, why don't we see it?") in the sci-fi world. Alastair Reynolds' Revelation Space [1] series of books (highly recommended) have the same premise, as does Greg Bears "Forge of God" [2] and from 1987 and its followup "Anvil of Stars". Also, I hear (haven't read it yet), Peter Watts' "Blindsight" [3]

Also the late Stephen Hawking's fears.

[1] https://en.wikipedia.org/wiki/Revelation_Space_universe

[2] https://en.wikipedia.org/wiki/The_Forge_of_God

[3] https://en.wikipedia.org/wiki/Blindsight_(Watts_novel)

Spoilers.

In Blindsight, humans are the only intelligent lifeform in the Galaxy that are conscious. Thus, they're the only ones that produce art, entertainment, or just talk to each other for "no reason."

Other intelligent life in the Galaxy does communicate, but only to exchange resources in a mutually beneficial way. So when a bunch of Earth transmissions of War of the World's or talk news finally make it out there, one set of aliens begins receiving and decoding this information. As it becomes clear the information is meaningless and worthless, it becomes obvious to the non-conscious aliens that humans are waging an information attack on the entire galaxy. They are essentially ddosing the Galaxy with worthless em radiation. So, the aliens come to kill them.

Luckily the space vampires beat them to it.

Are we broadcasting signals?

Yes, for about a century.

I've always thought of EM (Radio/Communication Technologies) as potential tools to confirm specific sources/locations of other intelligent life as well as possibly their purported agenda/intention/lifestyle/threat-level? (or level of intelligence and even to develop [flawed but useful, a.i. based] predictive algorithms of their future likelihood of physical contact/threat and/or their rate of scientific advancement, based on analysis of numerous factors including their encoding used, past broadcasts compared to current, means of broadcast, etc. Etc. Etcetera.) [STRICTLY LIMITED TO/AT the time of the broadcasts, not at the time we receive them... BIG DIFFERENCE IN ASSUMING THAT THE TWO ARE THE STILL THE SAME!]. Never in my wildest dreams, would I consider us as humans advanced enough to ACTUALLY RESPOND (IN WAY THAT WAS COMPLETELY SAFE, FORETHOUGHT, LOGICAL, CALCULATED, MORAL, AND MUTUALLY-BENEFICIAL!). We shouldn't knowingly, directly communicate or reply to forces beyond our wildest comprehension, for what we wish to be a dream for the future of mankind could quickly turn to its worst nightmare, if we are not careful, moral, loving, prudent, and conscientious. We should not have the audacity to treat our supposed Galactic neighbor(s) based on behavioral assumations, if we ever resort to treating them any way whatsoever, which until we reach a far greater point of advancement (both materially, defensively, socially, scientifically, technologically, and, in all honestly, Spirtually) I advise against, 100% completely. Just my take. Learn what we can without exposing ourselves.

I know we have optical telescopes in space. Don't we have radio telescopes in space too, like SETI? Why not?

Optical telescopes are in space to avoid the effect of the atmosphere. Radio telescopes aren't effected in the same way so I don't think there would be an advantage for them to be in orbit and it would cost a lot more.

The atmosphere is really good at distorting optical signals. It's not as good at distorting radio waves.

Additionally, radio telescopes tend to be enormous - much bigger then optical telescopes. It's one thing to launch a bus-sized instrument into orbit. It's another to launch a stadium-sized instrument into orbit.

3 billion miles away, typo?

lol yeah.

Other articles say 3 billion light-years, slightly further than 3 billion miles haha.

Ever so slightly.

> 3 billion miles away, typo?

"from a mysteriously noisy galaxy 3 somewhere between Neptune and Pluto"

So, the "mysterious signals" are Fast Radio Bursts?

I mean, it's not that we know what those are exactly, but I was under the impression that nobody really takes them as alien broadcasts. And they have been observed before- just not by SETI's CNNs apparently?

447 comments here and not one questioning how this "mysteriously noisy galaxy" ended up being closer to us than Pluto.. (article says this galaxy is "3 billion miles away", Pluto is 4.67 billion miles from Earth).

Seeking for alien messages sent to nobody is silly, we have more chances to find extraterrestrial civilizations if we look for two points that seem talking to each other, I know, easier said than done.

We are not looking for data. We are looking for slow, noisy beacons to know where to look for the data.

Much like WiFi AP beacons are on a lower frequency than data transfers or how lighthouses are hard to miss.

https://www.obspm.fr/spip.php?page=imprimer&id_article=2998

im Kind of stumped at the whole advanced life form contacting us thing.

1. We didnt even emit any real radio waves until just a century or so ago. How did they detect it to know to emit something to us? 2. How much power would that entity have to emit from that distance to be detectable by us? 3. And for civilizations more than 50 light years away, how did they know to even push a signal in our direction if they didn’t sense a single thing except maybe a certain type of atmosphere?

Don't respond right away, it looks desperate. Wait a day or two. Does anybody know if SETI automatically sends read receipts? Turn that off if at all possible.

Is there an explanation of FRBs that uses terminology that someone with a University education of DSP would be accustom to?

The first paragraph of the article says the galaxy is 3 billion miles away. That might be a editing error.

> a mysteriously noisy galaxy 3 billion miles away

Some close galaxy, that!

I want to believe in SETI's findings, but is this true?

This is cool, but TC's site is shit. THis seems to be just a article to push you to a iPhone advertisement that loads once you scroll down.

more like deficient machine learning code rather than actual intelligence findings.

The novel Contact by Carl Sagan was pretty good in this area of SETI.

I have trouble connecting to the cell tower down the street. I don't know how they are going to receive a real communication signal from that many light years away.

Doesn't have to be a signal with meaningful data, just something that can be identified as not noise.

As a serious question, aside from communications, what are examples of things they are looking for?

A lot of unexplained happenings occurring all of a sudden. First mysterious signals from space and now the sudden closure and lock-down of the New Mexico Solar Observatory: https://www.abqjournal.com/1219922/nm-solar-observatory-clos...

Was that observatory even operational?

That's a good question? Only someone local from that area, e.g. not me, would be able to answer that. Here's another question, even if it was not operational, then why all the secrecy surrounding the closure last Thursday. Even if it was some sort of break-in, or similar, occurrence, there is usually some sort of PR of some kind, but not providing information usually leads people to speculate, e.g. UFOs, aliens, which is now the case on social media sites: https://www.kansascity.com/news/nation-world/article21838556...

2 things is “a lot”?

Aliens == God

As humans, we wish something greater exists. It minimizes the noise in our otherwise meaningless lives. It gives reason.

And so we make up stories and find stories in signals and get excited at the prospect that _this_ just might be it.

But it never happens. And we go on searching and believing, and then we die.

How do aliens “minimize the noise in our lives” and “give us reason”?

The difference is that there are falsifiable hypotheses about aliens, and there are valid scientific reasons to believe they might (and statistically probably should) exist.

I have trouble finding it, but I think Thoreau at some point says you can find out what an atheist thinks of god by what they think superhuman aliens would be like. Definitely worked for Stephen Hawking.

Why do they have to be "something greater"? Most people would be thrilled if we found the alien equivalent to a jellyfish. People like aliens because we're curious creatures and aliens are unknown and interesting.

I've never understood why some people feel the need to inject their mopey nihilism into everything.

Quite the opposite, my friend. I'm a humanist. IMO each bit of energy expended in the search of aliens is an opportunity cost to do something real here on Earth. So while you get excited about theoretical space jellyfish (or colonizing Mars, or the Second Coming of Christ (not you, specifically, just in theory I group these together)), I will excite myself with the alleviation of human suffering and preservation of planet Earth.

> each bit of energy expended in the search of aliens is an opportunity cost to do something real here on Earth

How do you feel about other activities that don't provide immediate, tangible relief to human suffering or environmental impact? What is your opinion of people who devote their lives to artistic, literary, musical endeavours, or who write software for social-media companies?

How long would it take radio waves to travel 3 billion light years? If it is a communication it would be from very far in the past. Assume it takes life about the same time to evolve on other planets wouldn't that mean that we wouldn't expect to start hearing radio communications until billions of years from now?

Radio waves travel at the speed of light...so 3 billion years.

Yes, assuming this is an actual intelligent life sending us radio waves, we're seeing their signals sent 3 billion years ago. So it's entirely possible their species already went extinct or they left their home planet for galactic expedition. Practically, nothing is the same about this civilization since they sent this signal.

To put this into perspective: when this civilization sent this signal, there was merely unicellular life on the earth!

Reply on news.ycombinator.com