Jokes aside, is there really any practical value in this sort of research, or is it the kind of thing that we do because it's interesting and kinda cool? Don't get me wrong, I think it's valuable for that alone, but...
Also I think science works the way that you use your fantasy to come up with outlandish things, and then try to rule them out with logic.
Once it is done, possibly much much much later, somebody may stumble upon it and use it in some creative (and unforseen) ways for other research.
On the other hand if you give any probability to alien existence, then this is very much practical already in the search for them.
In many ways it is too early to do this research, so it is a kind of art (as is a lot of research, imho). As long as only a few people do it, it's cool and useful so we can be aware of our potential future.
On the other hand, since we have no credible evidence of extraterrestrials, it would be surprising to find a civilisation so advanced to build a Dyson sphere. If they can build Dyson spheres, wouldn't they already be all over the place?
Ok, I suppose I should actually go read the paper now...
Would such a civilization spread to more than one star is actually also a question, or would they control their population rationally stay on their Dyson sphere and only start to move when the star had less than 100,000 years left to go.
Only some Dyson sphere variants, like Shkadov thrusters, are primarily conceived as ways to move around. Which personally seems to me less likely, is a civilization, as well as the ability to construct these objects, also going to have a species level interest in going exploring?
Check your math: this galaxy is ~10^5 light-years in size and ~10^10 years in age.
1. Not control their population for some reason.
2. Had some sort of interest in exploring.
3. Implicit also in the speed of light thing, would find it really interesting to send a portion of their population to the next available and suitable star which might be enough light years away to make communication impractical. I mean for our civilization there is some level of argument that says it would be a ridiculous idea to move to a new solar system and we have an intellectual exploratory streak in our species.
I mean we are currently not at the level of being able to do a Dyson sphere, it took us 4.543 billion years (age of earth) to get to the part that somebody could conceive of it. There is also some discussion as to whether or not our civilization is going to last, so given that and the other things I said it seems unlikely to me that any Dyson sphere civilization would actually build more than one, but maybe some build two because binary stars or some other weird circumstance which makes it worthwhile to do.
on edit: if we get to Dyson sphere building capabilities which seems really unlikely, will we build more than one? How many more?
So again, still haven't heard any argument why an alien civilization achieving the ability to build Dyson spheres, even if they did so far enough in the past that they would then have adequate time to traverse the galaxy afterwards, would then have to be everywhere?
yes, there is, if the achievement of Dyson sphere building happened long enough in the past for there to have been sufficient time. 50,000 years ago even, no. The length of human civilization is 6000 years approximately, what if this civilization much, much older than ours 6000 years ago just started building it's first Dyson sphere. For some reason the assumption is that it was far enough in the past that they COULD be everywhere if they wanted to.
But then the phrasing is not that they could be everywhere but rather they would be everywhere, hence no civilization has built Dyson spheres. A lot of this theory that the aliens will go about building lots and lots of Dyson spheres seems based on the assumption that they will be a lot like us, but actually I don't even think we would ever build more than one. If we built a Dyson sphere it would be because we were at the point we needed the energy and we had the technology to do it of course, and we had a political system that could harness everyone to do it. But once we had the Dyson sphere I am not sure we would ever be at the position were we would need another one. Since people tend to have fewer kids the higher their standard of living it may be that with the standard of living of Dyson sphere civ that our population would be at replacement level, that is to say we would never need to move from one Dyson sphere until the sun was just about used up.
So again, sure there is sufficient time with waves of colonization (started far enough in the past) - but waves of colonization assumes a species that has a colonization urge and perhaps one that has a colonization urge greater than that of humanity. That's a pretty big if, considering all the other big ifs in the whole building a Dyson sphere scenario.
Galactic orbits are far more chaotic than the sedate stable orbits within the solar system - stars closely approach each other on a somewhat regular basis.
They’re crappy computing devices. Even if you figured out how to program one — and that’s an “if” that would make Sagittarius A* look like a neutrino — there’s no way to read the information out except Hawking Radiation, and that would take 10^70 years.
https://youtu.be/0GLgZvTCbaA (8:36)
I figure they'd have to be.
They'd need more than a solar system's worth of raw resources to build the sphere. They may need more than a solar system's worth of resources just to build the tools and craft to be able to build the sphere. They're going to need an insane amount of production facilities for various components, and that's going to take a massive amount of resources. That's going to require exploring quite a bit of a galaxy.
The number I’ve seen quoted is 50M years to colonize the galaxy: http://www.sentientdevelopments.com/2012/01/new-mathematical...
> they calculated that any galactic empire would have spread outwards from its home planet at about 0.25% of the speed of light. The result is that after 50m years it would extend over 130,000 light years, with zealous colonisers moving in a relatively uniform cloud and more reticent ones protruding from a central blob. Since the Milky Way is estimated to be 100,000-120,000 light years across, outposts would be sprinkled throughout the galaxy, even if the home planet were, like Earth, located on the periphery.
It’s actually so fast that advanced civilizations would have had time to colonize the galaxy and go extinct many times over without us noticing.
Or maybe their spheres were built so long ago they’ve already collapsed and been consumed by the stars again.
It’s a great mystery and interesting thought experiment though.
Our ancestors from 50M years ago are all extinct. So a civilisation spreading through the galaxy would have evolved in all kinds of different ways. It's not obvious to me that these diverse evolutionary strands would all still be interested in Dyson spheres, or space travel, or even astronomy.
There's a belief that's hard to shake off, that the properties humans have that we think most important represent some kind of evolutionary pinnacle. Typically, those properties are language, and a large brain for processing language. But if language and a large brain are really such great evolutionary advantages, why are humans the only creatures on Earth that have evolved those properties? Possibly language and a large brain are an evolutionary backwater.
At 0.25% of the speed of light, it would take us 1,600 years to reach Proxima Centauri; but it might take a lot longer to reach a star with habitable planets. We'd definitely need generation ships. After (say) a million years, we'd presumably have evolved to adapt to life on generation ships. It's not obvious to me that such adaptations would leave us fit to inhabit a planet. And perhaps adaptation to life on a generation ship means adapting to eating your fellow passengers.
Given the history of humanity, I find it hard to believe that the population of a generation ship could survive as long as 100 years without war breaking out on-board. We've had large brains and language for about 50,000 years, as far as I can tell; we've been warring the whole time. Maybe large brains and language pre-dispose us to war? If that's right, then it seems unlikely that intelligent life would ever spread far from it's planet of origin.
I'm very sceptical of the idea that any "civilisation" could ever spread far from its home planet. There are two things that we refeer to as a civilisation: a culture, and a species. Culture changes very quickly - over a single lifetime. But on a scale of millions of years, speciation is also pretty quick. So I can't see how any kind of homogenous civilisation or species could spread through a galaxy. They would have diversified before the train even reached its first stop.
So I don't have any insurance against being kidnapped by aliens.
Only two minor nits:
> why are humans the only creatures on Earth that have evolved those properties? Possibly language and a large brain are an evolutionary backwater.
Nearly every animal has language, for cooperation, competition, raising their young or to find a mate. Bees, whales, primates, birds, etc. all communicate strategically with some type of language.
> Given the history of humanity, I find it hard to believe that the population of a generation ship could survive as long as 100 years without war breaking out on-board. We've had large brains and language for about 50,000 years, as far as I can tell; we've been warring the whole time.
There’s been war somewhere the whole time, but not everywhere. Costa Rica, Iceland, Panama and several minor countries have no military: https://en.m.wikipedia.org/wiki/List_of_countries_without_ar...
It’s possible to find many countries who have not fought wars in the past 100 years. If you look more narrowly it’s possible to find communities unaffected by local war in hundreds or maybe even thousands of years (in other words, they fought a war but did so by traveling great distances, not fighting each other).
A ship would be much more like a tiny, isolated island colony rather than the geopolitical tensions that dominate the news.
Finally, wars rarely result in the extinction of both sides. Even if there was a large scale conflict it would likely be resolved prior to social collapse. There would be little incentive to kill so many of your fellow crew to the point where you’re putting every survivor at risk.
> Nearly every animal has language, for cooperation, competition, raising their young or to find a mate. Bees, whales, primates, birds, etc. all communicate strategically with some type of language.
There is currently only one species on Earth capable of even imagining the things being discussed here. On the other hand, it seems there may well have been more, but the others are now extinct.
One of these issues only we are discussing is the evolutionary viability of those abilities, and the fact we can do so suggests that it is, to some extent, up to us whether or not they will be.
Yes, I elided that bit, in the aim of brevity. I think there is a difference between human language and animal languages, in that human language is "creative" - we can freely create new utterances with new meanings, and expect to be understood. We know this of human language, but I would be very interested to learn of evidence of it in other species (chimps come close).
But I think the cones thing is still interesting; it means that for any given maximum travel speed, there must be other civilisations that can never know anything about you, nor you about them.
There is no need for all, or even most, of the civilizational variants to retain those characteristics. As long as some variants do, civilization would continue its inexorable interstellar spread, it would just end up being lumpy rather than a relatively even wavefront.
Indeed, survivorship bias would seemingly tend to conserve the required characteristics and possibly start constraining the ways in which civilizational offshoots can vary. And it isn't hard to imagine stay-at-home variants succumbing to the influence of later arriving spreader variants to become spreaders once more.
It's difficult to imagine a discovery that would have more practical import than the discovery of an extraterrestrial civilization.
But anyway looking for Dyson spheres will not reveal any extraterrestrial civilizations.
To make the point, literally nothing can be classified as "discovered" under your rules because any alien civilization may know about everything we'll ever find or figure out, and if they know about it we can't have discovered it.
Columbus was a murderer and people in America before he got there deserved way better but this type of nitpicking correction is just noise if you don't even say what is a more appropriate phrase.
Why, yes, of course - even in the immediate short term the ships returned from expeditions with gold and slaves; and from the very start the exploration voyages were planned and funded solely as a practical endeavor for trade and looting, not as an intellectual curiosity.