Where are they? Why I hope the search for ET life finds nothing (2008) | Hacker News Reader

Where are they? Why I hope the search for ET life finds nothing (2008)

fermatslibrary.com

78 pointsgodelmachine117 comments

There's an obvious possibility that people ignore because it's not very sexy: maybe life is common, but sending messages clearly over interstellar distances is pointless and extremely expensive.

Maybe the energy cost of transmitting a signal that can be clearly heard over interstellar distances -- mixed with the time/distance barriers of interstellar travel and communication -- makes it kind of pointless outside of novelty. (Not to mention any communication would happen on the scale of rise and fall of civilizations -- how do you even have a coherent conversation across hundreds of years?). I mean maybe most societies that form just don't have the energy and willpower to colonize outside their solar system. They might also be like us where dominant civilisations and philosophy’s rise and fall every few years — meaning not enough stability for a 50000 year long conversation

Perhaps the universe is silent simply because there's no reason to speak up.

Presumably any space-faring civilization would be interested in knowing if others exist; at a minimum, first contact (should they have any expectation of external life) would likely offer an extreme advantage in whatever competition they have locally (eg technological gifts, information exchange, prinary point of contact, etc). Furthermore, if they are spacefaring, they will require long-range transmissions regardless: it would be odd to think they’d send ships into multi-year journeys without being able to phone home, or having the tech and not utilizing it (a lost ship is likely costlier than transmission).

A civilization not capable of spaceflight might be in your position, incapable of producing transmission cheap enough, and not being curious enough to cast it into the void, but otherwise, any being capable (and willing) of long-distance travel should find sufficient use for long-distance communication to utilize it, independent of a search for alternate life.

That is, advanced civilization should be noisy for their own sake. (Though perhaps in a manner we can’t detect, or don’t expect).

Communication within a civilisation is quite a bit different from highly speculative permanent signals to billions of starts in the hope that someone is listening. And even if someone is listening, they might not be able to answer. So this sounds rather unlikely to me.

A bigger issue is: would they actually send spaceships on multi-year journeys to other solar systems? If they would, then why aren't they already here? Some of those civilisations must have a million or billion year head start on us. Plenty to colonise the galaxy, yet we see no trace of them here.

So the odds of there being interstellar civilisations out there is extremely slim. I think our best bet to find alien civilisations is by detecting the signature of alien megastructures; Dyson Spheres and the like. Tabby's Star sounds to me like the most likely way we might find alien life.

> If they would, then why aren't they already here?

Space is really really big and there are a lot of star systems. Maybe it's just statistics.

> Plenty to colonise the galaxy,

I think you're seriously underestimating how big a galaxy is: https://www.reddit.com/r/theydidthemath/comments/2i6le7/requ...

I know how big the galaxy is, but I also know how much a billion years is, and how fast exponential growth grows.

Of course a civilisation won't be able to keep growing exponentially for ever; pretty soon only the outer rim will have anything nearby to colonise. But still, a billion years is a lot.

But if colonies don't grow up to colonise other planets, you're stuck with linear growth, which is never going to be enough.

> maybe life is common, but sending messages clearly over interstellar distances is pointless and extremely expensive

It certainly is. I've heard that we wouldn't be able to detect Earth's most powerful broadcasts from a distance of half a light year. So expecting broadcasts to make it across interstellar distances is ridiculous. Tight beam signals might work, but then you've got to know somebody is listening. Nobody knows anyone here is listening, so nobody is sending anything to us.

But I thought the real paradox according to Fermi is not that we don't receive signals, but that they're not already here. If interstellar travel and colonisation is even the slightest bit possible, and spacefaring civilisations are somewhat common, then some of them must have had a millions or billions of years head start on us, which should have been plenty to colonise the entire galaxy. Why did nobody discover this fertile planet somewhere during the age of the dinosaurs?

The obvious solution here is of course that interstellar travel is so impractical that even in a million years, nobody will ever colonise another solar system.

That, or Erich von Daniken was right.

>The obvious solution here is of course that interstellar travel is so impractical that even in a million years, nobody will ever colonise another solar system.

It's also entirely possible that a civilization that colonizes another solar system won't also inevitably colonize the entire galaxy. I think people assume this because the mathematical progression makes sense and because the precedent of humans colonizing other continents makes it seem intuitively plausible, as if space were just a bigger ocean. Decades of space opera and science fiction stories have turned the metaphor into an archetype.

Yet if it is true that rockets and radio waves are all anyone ever gets, then every new colony is an investment of hundreds or thousands of years' effort or more, assuming there is always a stellar body nearby with a planet which is amenable to colonization, as if stars were equidistant from one another, and assuming all previous colonies continue and survive.

Many people seem to assume that either the entire galaxy must be converted to computronium by Von Neumann probes or no life exists elsewhere in the universe, but to me, detecting the signs of interstellar civilization anywhere in the universe is the least likely possible scenario even if life is common.

Even if it takes a colony 10,000 years before it's ready to colonise, a billion years is a lot of time. If each colony spawns a new colony every 10,000 years, that's enough to colonise the galaxy.

But it's entirely possible that colonies don't feel such an urge to spread. We may feel it because our planet is fairly densely populated, but a high-tech colony with all the education and medical tech to not require large families, might grow so slowly that their planet will never feel cramped.

One thing that strikes me about the idea of colonising the galaxy is it has practically no economic benefit to the people making that investment. Not to mention that any society you set up on a neighbor star is likely to diverge culturally (and perhaps biologically) in significant ways — perhaps to a point where they’re more likely to be mysterious rivals rather than friends.

>Perhaps the universe is silent simply because there's no reason to speak up.

Perhaps the interactable bubble of our simulation end long before the next closest star.

Perhaps other civilizations never even messed with radio transmissions, perhaps they got to fiberoptics before or around the same time and decided to just used wired connections for everything.

Perhaps other civilizations long ago abandoned radio for some other form of transmission that we've yet to even discover, some multi-dimensional/subspace communication or some sort of quantum entanglement or maybe they communicate chemically and can transmit massive amounts of data with particles in the parts per million or billion.

Or maybe their civilizations came and went time and time again spanning billions and billions of years.

I once did some math ( https://www.ryanmercer.com/ryansthoughts/2014/11/30/this-jus... ), if we assume 1 sextillion stars in a total of 100 billion galaxies in the universe (likely a quite low figure) and that 1 in 2 of those stars has a body orbiting it that hosts life and that 1 in 2 of those worlds has at least one tool-building species that gives you 250 septillion planets with tool-building life. That gives you an average of 25,000 tool-building worlds per galaxy.

Now let's take our galaxy and let's assume that in the first billion years of our galaxy, there were ZERO tool building species. That leaves you with 12.21 billion years to divide 25,000 civilizations over a galaxy with 100,000-180,000 light year diameter. Let's assume 140,000 light years. That's more than 15,000,000,000 square light years.

That gives us 1 tool building civilization per 600,000 square light years spread out over 12 billion years.

Obviously this figure could be way way lower than in reality. If a species develops space technology they could easily begin to spread. Even if a civilization needed a thousand years to spread to a neighboring star in 10,000 years you could have a presence in 512 star systems, in 20,000 years 524,288 star systems.

> There's an obvious possibility that people ignore because it's not very sexy: maybe life is common, but sending messages clearly over interstellar distances is pointless and extremely expensive.

That's the simplest solution to the Fermi paradox. Perhaps interstellar communication and travel are simply too challenging and uneconomic to be feasible.

This seems unlikely. We already know about technologies that seem likely candidates to enable communications and travel between stars. Give us a couple of centuries without global disasters and we will master them.

Do we? Our physics today suggest there are hard limits. We do have some creative theories (Alcubierre, wormholes) to work around those limits, but they could run into issues and in current forms require massive energy that could well be impossible to generate or harvest. Laser/solar sails seem most likely to me, but could be limited to small payloads and the general vicinity of our solar system. As much as I like sci-fi and real science, it seems quite likely that there are physical limits that keep intelligent life constrained to their solar system. Space is really really big.

> Humans have, to date, seen no sign of any extraterrestrial civilization.

We do not know that and it may very well be false.

Yeast was known of and observed for thousands of years, but was not discovered to be life until the 1800s. The signs of life were there, but were not recognized.

It is just our human bias to envision complexity as only occurring on earth-like planets, on human-like time and size scales, communicating over the EM spectrum, formed of baryonic matter...

We don't ask what Great Filter prevents the aliens from speaking English. But we might if English was the only language known on Earth. What languages other than DNA are spoken in the universe?

It is just our human bias to envision complexity as only occurring on earth-like planets, on human-like time and size scales, communicating over the EM spectrum, formed of baryonic matter...

The argument works just as well if you stipulate that it covers only sufficiently human-like complex life. The speculated existence of life composed of galaxy-scale non-baryonic matter or something doesn't affect at all the question of where all the other more prosaic life is.

I vaguely recall an article describing reasons why really exotic (e.g. galaxy scale) life doesn't make a whole lot of sense. One problem is that no matter how it is organized or what it is made of, light speed prevents it from communicating rapidly. If it doesn't communicate rapidly within itself, it can't develop or evolve much in the lifespan of the universe, at least so far. You can deduce various constraints on "intelligent life" without making simplistic assumptions a priori that humans are normal, but rather starting with what we know about physics.

Since we're on the topic of really exotic, how about a complex proton arrangement inside a star having all the properties of intelligent life? This wouldn't suffer from light speed constraints. Would it violate other constraints from fundamental physics?

It reminds me of the Boltzmann brain hypothesis. https://en.m.wikipedia.org/wiki/Boltzmann_brain. It's indeed really exotic and I'm not sure how long this intelligence could exist.

Frederik Pohl wrote a novel about just such a creature.

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

What if intelligent life exists all around us, but operates on vastly different time scale? For example, being thousand of time slower or faster? It would be almost impossible for us to notice each other either way.

Time lapse photography can make plant behaviour seem intelligent. The way pea plants put out fronds that 'reach out' to attach to nearby structures in order to stabilise the plant as it grows taller.

I think of time lapse photography sequences as how a tree might see the world. The movement of animals too fast for it to react to in a similar, but larger-scale, way that flies are usually too fast and agile for humans to catch or swat.

In one of Terry Pratchett's books an intelligent tree wonders why the sky keeps flickering.

There’s a lot wrong with this “maybe they’re all ascended beings that we can’t detect” line of thought.

Firat, the EM spectrum is radiative energy. Simple as that. It’s everywhere, and postulate that it isn’t detected because the Ascended Ones have moved to woo[0] technology, assume ms that woo tech doesn’t radiate anything in the EM spectrum, not even heat. That’s an even bigger lift.

Furthermore, this transition to woo technology occurred far enough into the past, that no evidence of pre-woo technology exists in the light cone[1] visible to Earth. Keep in mind, even Bronze Age development can be detect in atmospheric samples.[2]

Second, “formed from baryonic matter”? Are you postulating noncoporeal life? If so, I’m running a subscription service to educate people how to communicate these noncoporeal living beings. I take cash and Venmo.

[0] https://rationalwiki.org/wiki/Woo

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

[2] https://www.sciencemag.org/news/2018/11/why-536-was-worst-ye...

You projected this "ascended beings"/ghosts interpretation onto parent post which said nothing of the sort.

All parent was saying is that there could be life that look unlike anything that we currently know to be life. There could be organisms that are the size of solar systems, operating on such long time scales that we might not recognize it for life.

Anyways non-baryonic matter includes: neutrinos and free electrons, dark matter, supersymmetric particles, axions, and black holes.

Suppose there's a life form based on dark matter or black holes.

Neutrinos pretty much don’t interact with anything, including other neutrinos. Black holes are singularities, which arent intelligent, nor meet any definition of life.

Dark matter... well given that we can’t even describe what it is, I’ll pencil that in as “maybe.”

Regardless, all of this is pointless speculation with no evidence to support, nor even inform this line of thought. One might as well be arguing about a pinhead’s carrying capacity of noncoporeal entities, the nutrient value of unicorn meat[0], or flat earth geography.

[0] While the meat itself is superficially similar to horse meat, it’s unfortunately poisonous due to the Unicorns’ Unfortunately, there’s none, due unusual biochemistry involving arsenic, lead, and polonium.

It's irrelevant anyway: the argument is specifically about the conditions required for "...an Earth‐like planet to produce an intelligent civilization of a type that would be visible to us with our current observation technology".

Intelligent clouds of dark matter just don't bear on the argument, whether they exist or not.

Right, and the author glosses over UFOs but the evidence is undeniable.

The evidence that there is something happening in the skies is pretty strong, but the evidence that it's extraterrestrial visitors is weak.

They're a complete mystery. There is extensive evidence that US and international militaries and space programs have released. That evidence points to physical objects in the sky that respond to our aircraft and behave in a way that physicists have said is not possible given our level of technology.

Maybe they're from a small African nation that's hiding their technology in plain sight. Maybe they're time travelers. Maybe they're the result of some distortion in the earth's magnetic field. Maybe they're aliens.

It's a scientific mystery but it doesn't get the proper funding and respect because of the stigma. This is a huge loss.

Do me a favor and stop right here before going further and defend this position.

I didn't say they were aliens. Militaries have released footage UFOs and physicists have poured over the footage and ruled out every other possible explanation.

> physicists have poured over the footage and ruled out every other possible explanation.

This seems unlikely, to put it mildly.

I should rephrase, scientists have ruled out natural phenomenon and the result of human technology. There are other explanations but they are further on the fringes than alien civilizations.

See my other comments with credible sources and the discussion here: https://news.ycombinator.com/item?id=16002771

Do you have any sources for that?

https://www.washingtonpost.com/outlook/the-military-keeps-en...

http://www.nationalarchives.gov.uk/ufos/

https://cosmosmagazine.com/space/why-we-should-take-ufo-sigh...

https://www.cia.gov/library/readingroom/collection/ufos-fact...

Credible sources, if I may add. As in, what is the scientific consensus?

I am often asked by friends and colleagues, “Why don’t astronomers see UFOs?” The fact is that they do. In 1977, Peter Sturrock, a professor of space science and astrophysics at Stanford University, mailed 2,611 questionnaires about UFO sightings to members of the American Astronomical Society. He received 1,356 responses from which 62 astronomers – 4.6 percent – reported witnessing or recording inexplicable aerial phenomena. This rate is similar to the approximately 5 percent of UFO sightings that are never explained.

As expected, Sturrock found that astronomers who witnessed UFOs were more likely to be night sky observers. Over 80 percent of Sturrock’s respondents were willing to study the UFO phenomenon if there was a way to do so. More than half of them felt that the topic deserves to be studied versus 20 percent who felt that it should not. The survey also revealed that younger scientists were more likely to support the study of UFOs.

https://cosmosmagazine.com/space/why-we-should-take-ufo-sigh...

> Over 80 percent of Sturrock’s respondents were willing to study the UFO phenomenon if there was a way to do so

Over 80% say that they would study them, but there's no way to do that (in a scientific way). More than 50% say they should be studied. The majority did not conclude that they are extraterrestrial.

There are plenty of non reproducible phenomena that are studied scientifically and UFOs wouldn't be any different. Funding can be allocated to deploying observation devices with instruments specifically for this purpose. Evidence can be cataloged and analyzed to find patterns. Unfortunately no prestigious scientific institute is going to allocate the proper focus.

This isn't happening to the extent that it should because of the stigma involved, not because of the lack of evidence or lack of capability to investigate that evidence. There are no good hypothesis that fit within the framework any conventional scientific theory but that doesn't make the evidence any less reliable.

Let's stick to the facts, because you're speculating here:

- There are UNIDENTIFIED flying objects

- (it would seem that) the scientific consensus is "we would like to investigate this, however we cannot"

- a small percentage of these UFOS are not explainable in conventional ways.

The rest are conjectures and speculations. Non-reproducibility is not the biggest issue, non-falsifiability is a bigger problem.

Scientists are saying: "we don't know, we should investigate, but we can't". You are saying: "they can't investigate, then it's obviously aliens"! I say they are Santa's little elves using camouflaged reindeer (this also explain the "flying lights": it's Rudolph's nose): prove my theory wrong.

TL;DR: if you can't scientifically study a phenomenon, or if no studies are done, science is not telling you what the phenomenon is. You can believe you know what that is, but it still just your belief.

> You are saying: "they can't investigate, then it's obviously aliens"!

You're putting words into my mouth. Nowhere have I said that scientists should investigate the extraterrestrial explanation of UFOs, they should investigate the phenomena without any preconceptions.

> Scientists are saying: "we don't know, we should investigate, but we can't".

They aren't saying that. They are saying there's a lack of funding and will. Take the time to read that article that I quoted:

https://cosmosmagazine.com/space/why-we-should-take-ufo-sigh...

What does the 'U' stand for again?

There are a number of flaws with this argument, but one major obvious one is the idea that finding life on mars would show the probability of life generating on a random planet is high. The premise of this argument relies on assuming life arising on Earth and Mars are stochastic processes that each occurred independently; on the contrary, there could be shared featured of Earth and Mars that make life more probable on those two planets than elsewhere.

The 'great filter' could be shared between the two planets.

Finding life on Mars, or anywhere in the solar system, would be huge and would radically improve our ability to predict life elsewhere. If it's chemically different from earth life, that would revolutionize our knowledge of complex chemistries. If Mars life is chemically similar but independent of earth life, that would suggest that life tends to use common chemistry. If life on earth and mars has a common origin, that would tell us a lot about the early solar system. In short, N=2 doesn't sound great, but it is lightyears better than N=1.

Earth and Mars are also close enough to have seeded each other: https://en.wikipedia.org/wiki/Martian_meteorite

Given the amount of waterbears and the fact that they are small enough to get blown off the top of the atmosphere by solar winds, I suspect that perhaps one waterbear per century has the conditions to briefly wake up on Mars and wonder what the hell is going on before dying.

Considering that they can survive the vacuum of space, 1000 times more radiation than other animals, few days at -200C (30 years at -20C), and they can be dehydrated for 10 years, i'd say they'd probably briefly wake up, wonder what the hell is going on, then doze off in a 30+ year hibernation state.

It's about as meaningful as asking 9 people in the same, small, rural town if they like going to the library, then concluding that x/10 people, in general, like going to the library. Maybe that particular town has a really shitty library.

Depending on the result, it could tell you a lot more about libraries than no result. For example if a large proportion do use the library, that's not necessarily evidence of high library use generally, but it does show that high library use is possible and that libraries are used in some places at all, where before you might not have known either of those things.

Furthermore even if life on Mars was seeded from earth, it tells us that seeding between planets is possible and therefore likely occurs in at least some other solar systems.

See the German Tank Problem. Even a sample of one tank is vastly better than no tanks, and even two tanks can be a surprisingly useful data set.

Or a really good one.

Or, maybe 9 just isn't enough to get an idea of the other 900,000,000,000,000,000,000... planets.

I like reading, but i hate libraries (as in physical buildings), at least in the western countries. With almost everyone having internet access, there's no point. Digitize everything, put it online.

I hate sports, but I don't argue there's no point to them because there's no point to them for me.

A library's advantage isn't just "musty old books" books (some young people, myself included, love physical books and have small apartments!). It's also a free, public space you can come to just be. If you're a kid who has no spending money, you can come to do your homework, or code. Especially relevant for kids who have a poor learning environment at home (too many siblings, parents fighting, etc.)

Are you currently in charge of the UK government, by any chance? I only ask, because presumably someone has to be and it doesn't look like it is the people on the telly.

Thanks for sharing your opinion I guess?

> The premise of this argument relies on assuming life arising on Earth and Mars are stochastic processes that each occurred independently

That isn't the premise. It's the premise of how it got there for a straightforward example, but doesn't avert the filter questions (regardless of how it got there).

I think you are on to something about shared dependencies, but have trouble thinking about the impact of these might be. They share more similar cosmic positions in the galaxy, perhaps have more similar chemical compositions, they both share the same sun. Is that enough?

This is an old argument, covering well-trod ground.

Somewhere in the ocean there's an island with only one colony of ants.

In that colony, there's a little ant-Enrico Fermi, doing little ant-things, writing in little ant-journals, wondering little ant-thoughts, including "Where are they?"

You have to bring a great amount of hubris to bear on this problem to reach any kind of conclusions. After all, we only have an example of one Earth, with one species of humans on it. I'm not sure we'd know what an alien was if one were standing next to us (metaphorically, perhaps actually). We have no common frame of reference to reason about such things. The best we can do is string together a lot of terms representing concepts through multiplication. This gives us the unsurprising result that lots of things multiplied by each other tend to get either really large or really small really quickly.

The question Fermi asked was a truly profound one. It was profound because it points the finger back at us, asking just what do we really know about the entirety of universe we live in?

It's a great question. We will be fortunate to see little tiny pieces of the answer in our lifetimes.

Highlighting text on a webpage so that you can focus on a particular sentence should never move the text and make you lose your place. I like the idea but don't make it a pop-in sidebar that moves the page.

Yes, the ux was horrible, especially on mobile.

On firefox I couldn't even enable reader mode on this page.

For an article that looks like typewritten pages, you'd think it would be perfect for printing. But it gets horribly butchered if you try to print it or save it as a PDF. Modern web development has robbed us of the beauty and simplicity of plain text.

Charlie Stross' "Accelerando" floats an interesting idea: Post-Tech-Singularity civilizations might naturally become isolationist because consciousness becomes tied to computing hardware that is dependant on abundant energy and low communication latency that you don't have unless you all cluster closely around a star, i.e. a small Dyson sphere. Leaving those ideal circumstances becomes unthinkable for the individual because it would mean lobotomizing yourself.

However, we should be able to see those Dyson spheres, and we don't.

Isnt the purpose of a Dyson sphere to keep all Energy inside? If thats the case, how would you detect such a sphere?

Maybe that's where the dark matter is. 80% of the universe, packed into small Dyson Spheres, where live is sprawling and we just cant see it. ;-)

> Isnt the purpose of a Dyson sphere to keep all Energy inside?

No, because that would be both impossible (see "black body radiation") and useless. The purpose is to use all energy produced by the star. But "using" energy doesn't mean it's gone (see conservation of energy) or that you have to trap it. What it really means is you want to use the low entropy inherent in a concentrated source of energy to perform work.

They would glow in infrared.

I think this is not giving enough thought on the topic of population growth. I believe in most rich/advanced countries population is declining, unless they have a lot of immigration, United States for example. Hans Rosling has some studies on this, his studies say that the world population won’t exceed 11 billion.

Also, people are having less sex than before. https://www.theatlantic.com/magazine/archive/2018/12/the-sex... which obviously is going to affect population growth.

Although, this could change if somehow we manage to live considerably longer lives. Then population would grow again. Which is the main promise of Scythe by Neal Shusterman.

We would need a very good reason to spend the resources to go colonize other planets.

Why does there have to be 'one' great filter... I think it's more a 'tiered' system... I mean on any given planet getting to eukaryotes is difficult..once you do, you've made it past 'a great filter'.... onto the next...

Everything in life is a battle to survive - even evolution. I don't think there even being a great filter means that we necessarily wouldn't pass through it... -- I guarantee you there's a great filter...if we never become space faring this world will die -- the sun will supernova. If humans survive to that day, and never leave the solar system then all life here will be snuffed out... If we do survive eons past the end of this solar system at some point the entire universe could contract, entropy could run out and all life would be snuffed out...

On a long enough time line -- everything in this universe will be filtered out.

Not to detract from your other points, which I agree with, but our star won't supernova. It doesn't have enough mass. It will go red giant and toast our planet.

It's because the simulation was built to simulate a culture that wasn't yet aware of aliens and alien interaction isn't part of the experiment. It's also less expensive in compute resources.

Our own DNA-based life may actually be the von Neumann probes the author mentions -- self-replicating spacecraft, controlled by AI and capable of interstellar travel via "Panspemia".

There is currently an excellent podcast exploring these ideas: "The End of the World with Josh Clark"[1]. Nicely produced, fairly deep content -- including audio quotes from Nick Bostrom among others.

This link is to episode 1, but for convenience in subscribing look it up on iTunes.

[1] https://www.stuffyoushouldknow.com/podcasts/the-end-of-the-w...

I've thought along these lines before, and am writing a hard science fiction novel with this premise. I love thinking about the possibility of other advanced civilizations etc as much as the next guy, but it does seem like the _other_ possibility is less represented in sci-fi and maybe in current thought in general. It's so fun to think about life existing and those implications, less time is given to thinking about life _not_ existing elsewhere and what that would mean. I get that to a degree. I feel like Debbie Downer just saying it, but in order of likelihood based on current observation, I would arrange the scenarios like this:

* Intelligent life only exists on Earth. This is what we have observed so far, so in absence of other evidence this is "most likely" with a large margin of error ;)

* Intelligent life does exist and is abundant, but we are among the most advanced. Hard limits in physics mean it is impractical to travel out of one's solar system, much less galaxy.

* We're among the most advanced because of a "great filter" after our current stage.

* We're among the most advanced because of a "great filter" before our current stage.

* We are a simulation

The idea that we'd most likely encounter a colonising civilisation in the form of von Neumann probes seems reasonable.

Imagine there was one (or even a few dozen) such probe currently occupying an asteroid somewhere in our solar system, slowly completing the millenia-long task of replicating itself. Would we have noticed yet?

If to expand that line of thought even further we shall conclude that we are alone in observable Universe.

Life as we know it tends to preserve itself - the instinct of self-preservation is the main feature of life. Others are just consequences.

"Hi-order" life will preserve not only one particular incarnation of it but various others too.

So as soon one civilization will pass the filter - it should help others to pass it.

And if we do not see that other hi-order one yet then it means this role is ours and no one is out there.

For humanity "hi-order" state of life is definitely far ahead - long way to go. If not the filter is ahead of us :)

>> So as soon one civilization will pass the filter - it should help others to pass it....

unless neither civilization knows 'when' the great filter is...and continues to expect it's in the future... this could cause fear of each other... fear leads to the dark side...

Interstellar war probably isn't good for the less advanced civilization. Let's hope when the time comes we're not the less advanced civilization...or the other one will become our great filter..

The great filter also could be a predatory civ that snuffs out any sign of life after they find it. For this reason many civs could be afraid to do anything to draw attention.

The possibilities that come to mind are:

1. We happen to be first.

2. They are on their way.

3. They are within reach and are not malevolent, nor allow the spread of malevolence, given the 'typical' billions years gestation period.

Or they exist but because the universe is huge and sparse we’ll never encounter each other.

My hunch is that life is actually prolific. It’s in the oceans of Encledeus (sp), may be in extremes on mars, and possibly more in other places. But it’s not industrial the ways we are.

> Or they exist but because the universe is huge and sparse we’ll never encounter each other.

That's a good hunch. As we've learned more, the universe has appeared to be larger over the years. This could keep destructive contagions from spreading. If destructive contagions are likely, we probably wouldn't be here.

I sort of file it under 1. where they are causally unreachable and we are singular in our sphere of influence.

Or maybe 2., but over time even if space is vast, we ought to bump into each other eventually. Folks won't rest until they probe under every rock. So maybe they are out there, maybe even prolific and they (or we) are on the way to meeting each other. Humanity ought to make itself durable to see it through.

> But it’s not industrial the ways we are.

I find this very unlikely. If you do some computer simulations, you can see that if "life" has minimal amount of freedom to get modified, it diverges to really interesting objects and exploits a lot of phenomenon happening in its virtual universe. Something as absurdly unlikely and crazy as symbiogenesis occured multiple times in our planet. It's unlikely if there is life out there, it'd stay simple and invisible.

My hunch is that life is extremely rare, if it exists at all. We know from computer science that evolution is a very good method to find ever-improving local optimas, so to me it's very likely if life exists, it'll evolve to galactic empires in a few billion years. And thus thanks to Fermi paradox, this convinces me that life must be extremely rare, or the Great Filter must be very effective or intergalactic communication/travel must be extremely expensive.

Our industry is possibly an emergent phenomenon. There are many species on this plant and only one has taken technology to our extremes. That could be a differentiator.

4. Or they haven't developed yet, or, they died out 50,000 years ago.

The Universe is a big place. It's taken us billions of years to reach this point where we're on the brink of becoming a multi-planterary species, and frankly, I'm still not 100% convinced we'll make it.

Depending on how much life there is in the Universe, and how effective The Great Filter is, the amount of civilizations reaching an advanced stage may simply be so low that the odds of two of them being within communication range of each other, while being at a suitable tech level, may be very low.

They haven't developed yet seems possible. Someone will be first, however unlikely it seems to them.

As scary as the great filter and dyeing out is, life is pretty durable. Even if we kill ourselves, some organism will probably slither out from under a rock after the ash settles and start afresh.

There seems to be a selection force that works against aggressive forms of life becoming too powerful. If your both belligerent and powerful, you have a chance of shooting yourself (your species) in the foot. So it appears that any sufficiently advanced civilization would be pretty benevolent and that this might be a necessary condition to advancing.

If we fail, there's still a chance that another intelligent species manage to develop on Earth before the planet becomes inhabitable for whatever reason.

That doesn't help us, although it does raise a few other questions, like "How do we preserve knowledge for the future?".

If you liked this, you might enjoy "Light of the Same", which examines the Drake equation and seti in the light of all the planets that have been discovered.

https://www.goodreads.com/book/show/36236156-light-of-the-st...

I wonder if the availability of fossil fuels is the great filter? My understanding is that all that plant matter didn't decay only because fungi hadn't evolved thr ability to break it down, and thus fossil fuels are a one time burst of energy that isn't going to ever be available again.

Do you have a citation for this understanding? I hadn't heard this before so I did a brief search and found [0], but this seems to apply just to coal which goes through a lignite phase during its formation [1]. I'm not familiar the details of how other fossil fuels are formed, but I was under the impression it usually happens under the seafloor, are the same mechanisms at play in an undersea environment? It seems like fungi are more common on land than at sea [2].

[0] https://clarknow.clarku.edu/2012/06/28/findings-point-to-fun...

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

[2] https://sciencing.com/types-fungi-grow-ocean-8467074.html

Ah, TIL.

I am wrong. I was unable to find any source for this, and, like you, found some countervailing posts, like this one:

http://www.abc.net.au/science/articles/2013/02/18/3691317.ht...

So, please consider the above comment retracted.

My latest favorite tin foil hats are The Watchers & The Cosmic War because otherwise perhaps we're going thru a Great Filter right now with global warming due to energy consumption, etcetera & I dunno if we're gonna make it at all

Human also occur in the earliest likely epoch of the universe:

* We have, astronomically speaking, just entered the epoch where the universe can support life. We have the required abundance of elements and conditions that give rise to life (stellar nucleosynthesis).

* Intelligence is an incredibly strange thing to evolve. Evolution is a gradient (the evolutionary whitening of the polar bear is probably the best example of this). There is no gradient to move down towards intelligence. You have it or you don't; you are reactive, instinctual, or intellectual.

* Intelligent life has also been demonstrated to be unbelievably improbable. With nature as the best laboratory, out of all the species that have ever evolved, only one on Earth evolved intelligence.

In layman terms, we are likely the "ancients," or rather we might be, as we could simply go extinct.

> There is no gradient to move down towards intelligence. You have it or you don't; you are reactive, instinctual, or intellectual

Disagree with this. You can compare the intelligence of various animals (humans, chimpanzees, dolphins, crows etc.) and see that there is a gradual scale rather than a binary (ternary?) switch.

> * Intelligent life has also been demonstrated to be unbelievably improbable. With nature as the best laboratory, out of all the species that have ever evolved, only one on Earth evolved intelligence.

I wonder whether this is actually true. Imagine the human society being transported to dolphin or shark bodies (they'd spawn there). Assume the following: food is not an issue in the short term and we retain our knowledge and we have quite a good control over our new bodies and can do what sharks or dolphins normally do.

Even with these advantages, could we recreate what we made on land?

Good point.

I would say that the defining feature of human intelligence is immediate and self-directed teaching. House training a dog takes many weeks and many rewards. Stopping smoking is a decision that a human makes and can immediately put into practice.

Using sharks and dolphins as an example, both would learn to avoid fishing nets and communicate that danger (which is not unique to humans), remember it (which is) to each other and their offspring (again, unique to humans). What's not done is seemingly more important than what is, because beating opposable thumbs is pretty hard (as you've pointed out).

No. Dolphins don’t have thumbs, and fire is a lot more problematical underwater.

Astronomical epochs are pretty long. While it's unlikely that extraterrestrial life has arisen billions of years before life on Earth, civilizations that are thousands or millions of years older than us should be as common as intelligent life in general. For example intelligent reptiles are not unthinkable, and their order had a hefty head start on mammals.

It's very hard to read these not-HTML and not-quite-PDF sites on mobile, especially with all the popups. Author might have something interesting to say but I can't tell.

Space is BIG with a capital BIG !!! Small is human.

Title needs a (2008) tag.

Bostrom dismisses, as a fallacy, the idea that the relatively rapid appearance of life on Earth is evidence for it being somewhat probable, yet it is just about as fallacious to think that the absence of life on Mars would be evidence for humanity having long-term prospects.

> UFO‐spotters, Raelian cultists, and self‐certified alien abductees notwithstanding, humans have, to date, seen no sign of any extraterrestrial intelligent civilization. [...] If large telescopes, NASA satellites, and omplicated mathematical data analysis are involved, it becomes harder for outside observers to mistake the work for the ramblings of UFO‐nuts and other crackpots.

The author makes it clear that for a serious scholar "UFOs" can a priori only be a subject of ridicule.

This behavior evidently started with Zeno of Elea's run on logic through reasoned argument. He's the reason we have the scientific method, basically.

Fortunately, the scientific method produced technology that allows me to post this comment. Unfortunately, limiting a culture's philosophy to only discussing things we can attempt to disprove results in limiting the ability to discuss something as if it were true, before we know it to be true by proof.

Example: I believe ʻOumuamua was a spacecraft. Can't prove it, but can't talk about it as a truth either, which sorta sucks given I figured (when I was a kid) aliens would be here by now. ;)

I'm picking up a lot of existential angst in this one. The author hopes we are the only intelligent species in the universe because why? I think spending so much time on the nature of ones own existence is to neglect the here and now. I say this as someone who confronted his own existential angst - it can drive you in any number of directions, none of which really matter for someone with an expected lifespan of 70 years. If life is so precious, why not go experience it while you can?

>The author hopes we are the only intelligent species in the universe because why?

Because if there is other life in the universe, then it's more likely that the Great Filter is ahead of us and that human civilization will end sooner. If we are the only intelligent species, then it's more likely that the Great Filter is behind us and humanity is more likely to spread across planets.

All I know is that if we're going to locate or communicate with any other advanced civilization out there, it's sure not going to be with radio waves. It will be with something a little more subtle that may not necessarily be constrained by gravity or the speed of light. Just my $0.02

It's likely that everything in the universe is constrained by the speed of light, so maybe radio waves are the best form of communication?

I think a lot of folks don't realize most real and hard science is done with radio waves. The tech is often associated with antiquated devices for music and news of erras by gone, but scientifically speaking, radio waves are pretty high tech. Electromagnetic Radiation has it's own brand problems though. We really new words not associated with early use cases.

Sadly most people don't realize what they see is 'radio waves', hence OP's misguided comment.

What you claim is indeed so very sad, but I wouldn't gnash teeth or loose any sleep over it.

There is no reason at present to believe such things exist or can exist. It also makes the fermi paradox much worse.

Without faster than light travel its possible to legitimately imagine that the size of space is a major barrier to colonizing the galaxy/observable universe. Maybe civilizations don't expend the energy required to expand when trips take thousands of years or most civilizations don't persist for the potentially millions of years required to saturate the galaxy.

Once you posit faster than light travel you have a situation where you have to explain why nobody in sphere bigger than the observable universe decided to saturate the observable universe in the mere centuries required to exponentially expand everywhere.

I wasn't positing faster than light travel, but rather a medium allowing a ftl transfer of information.

Outside of being a useful trope in scifi can you imagine any reason why information but not matter would be able to be transferred faster than light?

Spooky interaction at a distance shenanigans entanglement?

None of this can even theoretically be used for communication. Information doesn't travel faster than light.

Never say never

> All I know is that if we're going to locate or communicate with any other advanced civilization out there, it's sure not going to be with radio waves.

Never say never, indeed.

How can someone claim to not know and yet be so, so sure and arrogant?

I don't know

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