Fast Radio Bursts from Extragalactic Light Sails
arxiv.org
arxiv.org
1. the wavelength is relatively long, because you want a sparse microwave sail
2. the antenna is of finite size
3. the distance involved is intergalactic
Come to think of it, even if they were aiming directly at where we are now I would assume the light source would still be occulted regularly by everything between us and them.
A lot of people talk about bussard collector (magnetic scope for hydrogen/helium) to power fusion. But instead of collecting gas use it as a drag chute.
It could be an intra(inter)-galactic ballistic missile (i.e. no deceleration);
It would be a slap to the face though, look at these aliens that can choose to anihilate us or enslave us. (bad case). Just my thoughts, I'm nobody, no credentials, this is purely opinion/current mental maturity haha.
I don't know it's always depressing to me how massive space is, 40 years traveling at 50-150,000mph and the voyager just leaves our solar system hahaha. Crazy. (my numbers might be off depending on reference but that idea of 4 years of 9,000,000 feet per second) to get to the nearest start (dot in the sky) holy christ.
edit: haha holy crap it's approximately 984 million feet per second for like 4.6 years
edit: voyager speed ~36,000 mph, not sure how long that took to build up to that speed.
Plus new tech, new perspectives, old power structures being overthrown, etc... etc...
Things would change, and change is good for the future, but dangerous to those living through it.
this.
Muslim scholars have considered the possibility of life in the heavens as far back as the Middle Ages. Companions of the Prophet openly considered the possibility of religious beings in the heavens. It was recorded of Ibn-e-Abbas that "He even went so far as to say that they may have a Prophet like Muhammad (pbuh), a Adam like our Adam, a Noah, like our Noah, an Ibrahim like our Ibrahim, and a Jesus like our Jesus."
The Roman Catholic Church has also officially accepted that there may be intelligent aliens. So that covers a pretty large chunk of the world's religious believers already explicitly ok with it.
http://www.philipstallings.com/2015/06/the-biblical-flat-ear... Leaps readily to mind, along with the current state of Israeli politics, and you know... just a lot of politics.
You're right that lots of theologians are frankly much more impressive than the average adherent. What a pity that we're not surrounded by billions of theologians.
Similarly Zionism is not really a religious view as much as it is a political one. This can most clearly be seen in the fact that orthodox Jews oppose the state of Israel. They correctly interpret the Torah as saying that Jews have had the holy land taken away from them by God and it can only be re-established by God, not by the the act of men. Similarly the Koran says outright that Allah had given the holy land to the Jews, and groups like the Muslim brotherhood and Hamas that seek take Israel are motivated by political, not religious goals.
If anyone is going to create violence and chaos at first contact, it's not religious people but rather politicians that have a stake in a system that exposure to other, more equal or efficient systems may upend and industrialists that have a stake in the technologies that first contact will replace. There are so many other, historically consistent places to look for potential sources of revolt than mere ordinary people (in fact the majority of the human population) who are merely in search of the divine and greater meaning.
It's always these little small subsets hiding the allegedly "vast silent majority", but unfortunately they add up, they fight, and they ruin it all for the rest of us. I don't worry about the physicists with faith, I worry about the other 99.9999%.
I never thought I'd live to see the day Netanyahu was "moderate".
Do I have that about right?
(Short answer: we're alone, or at best among the very first tech civilizations in our galaxy. Longer version: given sufficient time and space, even the most unlikely possibility will take place with probability near 1. If there have been technical civilizations in galactic history at a level slightly above our own or better, it's near certain that somebody would have launched a self-replicating interstellar "Bracewell - von Neumann" probe, and they'd saturate the galaxy for the rest of time. We don't see them, though.)
Also, don't assume that alien life is like ours. It could be many orders of magnitude more efficient and in all likelihood isn't even biological in nature if they've reached the point where a million-year journey is feasible. It could just be a bunch of AIs constantly re-making themselves from resources they pass by as they coast through the universe.
They might not even have a destination! They could literally just be a bunch of machines that "live" in space. Floating around from place to place, grabbing resources from asteroids as they go by.
Lastly, in regards to energy: Why assume solar? Once you've reached speed you're not going to slow down much. Just leave the sails open to protect your craft from debris. I'd also expect a nuclear battery in such a craft to power on-board components. There's plenty of radioactive material in space to draw from for renewal as well. You also don't have to worry about disposal! Just toss it towards the nearest star system or asteroid belt and get a bit of thrust out of the action :)
> They could literally just be a bunch of machines that "live" in space. Floating around from place to place, grabbing resources from asteroids as they go by.
Whenever I think of what an advanced civilization would look like, I picture something like this (though not necessarily just machines). Something semi-nomadic, an entire civilization of ships in a big fleet, wandering together through the galaxy, stopping at various systems to gather some resources or explore the planets. Maybe the fleet breaks up and goes in different directions for a time, and rendezvous later.
The current thought now is that there's likely quite a few "rogue planets" out there, and other asteroids that haven't gotten captured by a star. However, the density of such things is likely to be so low, and you won't know until you get there what they're composed of, so it seems like a bad idea to plan a trip assuming you're going to stop at a bunch of asteroids and rogue planets to pick up supplies; you'll easily make your trip far, far longer. Don't forget also the big problem in long-distance space travel is speed. If you want to get to a particular star system, you need to get up to speed and stay there until you're ready to decelerate. You can't afford to slow down and stop at a bunch of rocks along the way, and you'll be going far too fast to capture the small ones. Most of your fuel will be used in acceleration and deceleration, so you can really only do that once most likely.
>Whenever I think of what an advanced civilization would look like, I picture something like this (though not necessarily just machines). Something semi-nomadic, an entire civilization of ships in a big fleet, wandering together through the galaxy, stopping at various systems to gather some resources or explore the planets. Maybe the fleet breaks up and goes in different directions for a time, and rendezvous later.
That doesn't sound like an "advanced civilization" at all, that sounds like a nomadic gang. An advanced civilization will value stability, and stay on their home planet(s) where all their infrastructure is located. They may very well send out exploratory missions, but those nomadic wanderers will not be the civilization itself, just one small part of it.
My thoughts were that a sufficiently advanced civilization would desire exploration, both for resources and scientific advancement. And you don't want your people spread out too far (for some definition of far), for a variety of reasons, the biggest being the consequences of the delay in communication and travel. For instance, scientists in different solar systems would find in next to impossible to collaborate: it could take years for news of one group's findings to reach the other, at which point they may very well have independently discovered the same thing, which is inefficient. Also, if one of the systems is attacked, or has some sort of crisis that requires assistance (plague, natural disaster, etc), the rest of the civilization would be unable to react in a timely manner. In short, it's safer to stick together.
Therefore, it would make a lot of sense to put your whole civilization into a fleet of ships with all your infrastructure (or maybe a single giant ship, Death Star sized), and move around. You could stay in a single solar system for a few millennia mining resources, or hop around looking for life.
Sticking to one place or a few nearby places is also an option, but I think it lacks certain advantages a fleet civilization would have.
Even on Earth, where the latency between devices on opposites sides of the planet is measured in hundreds of milliseconds, this is true.
The ten closest stars to Earth are within about 10 light years distance. While two way communication would be impractically slow, sending a continuous stream, UDP-style, to another colony would probably do the job sufficiently well.
This is incorrect. This is the "all your eggs in one basket" problem: if you have a big crisis in your civilization, you don't want everyone in one place, because your whole civilization could get wiped out. A civilization this advanced is likely also a very large civilization, so it makes more sense for it to have different parts in different places, just in case.
As for communications, as the other responder pointed out, a continuous transmission, assuming the data rate is high enough, will help keep the different locations in sync. Who cares if scientists independently discover things? Hopefully a civilization that advanced won't be so worried about patent rights.
As for "hopping around" looking for life, you'll do a whole lot better keeping your civilization in one place (or a few permanent locations better yet) and sending probes or exploration teams to a bunch of different places at once. Moving your entire civilization to only one star system at a time would be horribly slow, and sticking everyone in a giant death star means your energy requirements for transporting your civilization between stars would be ridiculous.
A fleet civilization wouldn't have any advantages besides mobility. You only need that if you have something you're trying to get away from, or have a well-founded concern that staying in one particular place could be dangerous. For Battlestar Galactica, it made sense because they were constantly being chased by the Cylons, and even then, the show did a pretty good job, at least at first, of showing what a PITA it is constantly being on the move. For a large, highly advanced civilization that doesn't have a bunch of genocidal robots chasing it, I just don't see how there's any advantage to remaining highly mobile. Mobility requires a lot of energy and greatly limits you in other ways. For a modern analogy, look at people today who live in RVs. Sure, they can drive their whole home away quickly and don't have to worry much about packing up to move, but they don't have much space, their home is easily damaged compared to normal dwellings, and it costs a lot to move it (because of the poor fuel economy). The only way living in starships makes any sense is if energy is basically free for you, which includes having a way to store immense quantities of it, because you'll need a lot when you're between stars.
My only other point is that the continuous transmission idea only works up to a point. Two populations that sufficiently far (I'd say hundreds of light years, but it could be thousands or millions of light years) apart are essentially different civilizations, because their societies would drift out of sync. Think about how much our culture, our language have changed in the past few centuries, and the rate of change in our society in only increasing. Extreme longevity or immortality might slow down the rate of change, but I'd argue that it wouldn't stop completely.
I guess my point is that civilizations have a maximum radius over which they can function, otherwise societies will drift apart until they are essentially distinct.
That's something I don't see much on these forums! Thanks!
>I think I was overvaluing mobility, because I figured once reaching a post-scarcity society exploration would become the top priority.
I know Star Trek isn't the most realistic TV show in the world, but I do think it (esp. TNG, esp. seasons 3+ because 1-2 sucked!) did a pretty fair job of showing what a post-scarcity society would look like, though to be fair energy was somewhat limited, but not that much.
In the show, most people/beings in the Federation lived on their home planets, or on colonies. There were a LOT of colonies; it seemed they were shown or mentioned every other episode. Most biological beings, assuming they evolve on a planet, and don't upload their minds into androids or something, are probably going to want to continue something like the lifestyle their ancestors had. In addition, there's huge logistical advantages to having stable facilities on planets. Where does the Federation build its starships? On planets, or in orbital construction yards (most likely, the components are largely made planetside, especially small but valuable ones like their computer equipment, and the ships are assembled in orbital shipyards). Where does the Federation mine the resources needed for ships and other stuff? Probably largely on planets and moons, though not necessarily the ones they live on, but the mines are probably very long-term and stable. And where does the Federation get the antimatter it needs to power its ships? According to the technical manual IIRC, they synthesize it from solar energy somehow, since antimatter is not naturally occurring in this universe. So all the infrastructure their society depends on for exploration (which is what many of those starships spend their time doing) is located in relatively fixed locations. Plus, the number of citizens in the Federation is surely enormous (they have thousands of members IIRC, and Earth alone probably has at least 5 or 10B by that time, depending on how many perished in WWIII and how many left the planet for colonization and of course the birthrate). The number of Federation citizens living full-time on starships is surely a tiny, tiny fraction of the total number.
>Two populations that sufficiently far (I'd say hundreds of light years, but it could be thousands or millions of light years) apart are essentially different civilizations, because their societies would drift out of sync.
That's true, but it really depends on the size of the civilization. If our civilization grew to span the nearest 50 star systems, for instance, they'd still all be within 16 light-years [1]. That's a pretty good-sized civilization IMO, and 16 years isn't that long to wait for a news about what's going on the homeworld (though it also means it's about 32ly between the farthest two colonies). A civilization spanning thousands or millions of ly would either be an incomprehensibly enormous civilization, or one which is really picky about which star systems it bothers with.
[1] https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brow...
If you expand that radius to 30ly, now you're looking at probably hundreds of stars. Couple that with the immortality you mention, and assume very stable governments (since a civilization with governments like ours is not going to be spanning multiple star systems, and wouldn't even get far off the planet) and I do believe the rate of change will be much slower so that it's not that big a deal if you don't learn about some interesting news or new music or something from one of the other colonies until it's 50 years old. And don't forget, we consider ourselves (humanity) as having a singular civilization, but how in-sync are we between different nations? Not that much; we don't even speak the same languages much of the time. Most likely, in such a civilization, the different worlds would have different cultures, and there's only be so much interconnection between them, mostly for trade but also probably tourism and such. But I guess now we're getting into an argument over the exact definition of "civilization"; do we have a singular one now, or are the US and China two separate civilizations with trade and cultural exchange? What about centuries ago when communication was all by hand-carried letter or word-of-mouth?
You don't need to travel in your biological bodies. You can upload your brains to the AI and then have the machine basically run forever. The machine becomes your universe, and it figures out how to best survive in the universe(Mine planets, asteroids, prepare better versions of it self etc etc)
we've always observe things in nature and then replicated them, if we saw something move faster than light that would advance our technology even if it's just by knowing it exists elsewhere.
I agree, the real value is know something is possible from there all things related make more sense and many decisions can be made based on that one fact.
We got along okay with Newton until Einstein came along and upgraded the model.
Does that make sense? I mean, if we discover that there are multiple universes, or that Block Universe is true.... who knows? Even then however, I suspect we'd run into something like Novikov Self-Consistency Principle, or we'd have noticed time travel by now.
For example, if you look at the maximally extended Schwarzschild geometry (the Kruskal-Szekeres extension) you see two asymptotically flat regions of spacetime connected by a "wormhole". It's probably just an artifact of the model though, and not anything physical.
A lot of the, "Math allows" stuff probably falls into that category, which is why when it comes to relativistic masses and velocities, you can't ignore quantum effects either.
I'm not sure it matters as long as space-time in one section is independent from another section. Maybe? Of course, I don't really know what I'm talking about since I'm not a Physicist. On a related note: As a kid, when I was still an innocent soul, I tried to build a perpetual motion machine and transmit high rate video-without first encoding it- through a phone line. It wasn't until I learned about conservation of energy and bandwidth that I understood the error of my ways. Point is, my ignorance is probably taking me astray.
However
What if you could connect those regions with this "warp drive"? You could create a causal link between regions that would otherwise be causally disconnected. You could carry information from the past to the future, or visa versa. You could essentially ignore the very fabric of spacetime.
Now... maybe that's possible, but I doubt that it's possible in the context of warping gravity. If M-theory is correct in some form, or MWI is correct (basically any multiverse theory) then maybe you could do it. After all, if the universe is a lower dimensional structure embedded in a higher one, you could imagine traversing those spacelike separations in the same way that you could do things in 3D that someone bound to 2D could not. That however, depends on so many "if's" that it's basically magic.
NOTE: I don't know nearly enough about astronomy to speculate which phenomena could be potentially artificial, but I do think it is a distinct possibility.
We are researchers, we try to explain the universe by improving our understanding of the physical processes that lie behind what we observe. The moment we bring aliens or gods into the picture to explain something for which we don't have an answer, we are doing a disservice to science.
If the elvish hypothesis proposes some experiments for testing and disproving it, then yes - it sounds more scientific.
We don't even know for sure that the majority of FRB data we have are from non-terrestrial phenomena. FRB occurrences at Parkes correlate strongly with lightning storms near the observatory.
But sure, it's probably angels or little green men. Why not. That's a hypothesis, you're doing science Jimmy!
With this attitude, much archeological evidence of pre-Columbian civilizations would never have been found. In fact, the entire field of archaeology wouldn't exist.
Although the possibility that FRBs are produced by
extragalactic civilizations is more speculative than
an astrophysical origin, quantifying the requirements
necessary for an artificial origin serves, at the very
least, the important purpose of enabling astronomers to
rule it out with future data.
It should be possible to distinguish between FRBs of
natural and artificial (light sail) origin based on the
expected shape of the pulse, as the beam sweeps by to
power the light sail. More specifically, the sail
would cast a moving shadow on the observed beam,
thereby leading to a diffraction pattern and multiple
peaks in the light curve based on the sail geometry.
A series of short symmetric bursts would be observed as
the beam’s path intersects with the observer’s line of
sight. Hence, looking for similar signatures in the
signal could help determine whether FRBs are powered by
extragalactic civilizations...Your attitude turns people off science; it's a plodding, unimaginative attitude that pours cold water on every novel idea without even bothering to explore it properly. The history of science is full of discoveries resulting from accident or whimsy, and I think speculation is an important exercise. Nobody ever got to the top of a mountain by meticulously documenting every step of the route.
So there's a risk you'll pin some hopes on an idea that turns out to be wrong. That shouldn't be bad for your career unless you do it all the time. A scientist who is never wrong about anything isn't taking any risks.
If you want that kind of excitement, try other area, in here, the only excitement comes from finding an answer to a problem based on science, not in some sci-fi novel.
P.S.: The simple explanation in this case is of course some physical process we can't understand. Not an alien civilization making planet sized machines to power their spaceships. This ain't star wars.