http://waitbutwhy.com/2015/08/how-and-why-spacex-will-colonize-mars.html
warning: long as fuck
http://waitbutwhy.com/2015/08/how-and-why-spacex-will-colonize-mars.html
warning: long as fuck
When the sky above us fell
We descended into hell
Into kingdom come
New Horizons snaps remarkable hi-res images of Pluto as it treks onward ...
Astronomers find probably not aliens.
But only probably.
Originally Posted by http://www.slate.com/blogs/bad_astronomy/2015/10/14/weird_star_strange_dips_in_brightness_are_a_bit_ba ffling.html
When the sky above us fell
We descended into hell
Into kingdom come
1500ly is a little too close for comfort if you ask me. Whatever it is we're seeing these scrubs get up to around their star, they were doing it about the time Rome fell. So lord knows what they'd be capable of right now, as I write this.
I for one am hoping for space dust as the explanation.
When the sky above us fell
We descended into hell
Into kingdom come
It is pretty close. If it were an alien civilization, then it would mean that they have no interest in systems outside their own, or they know that our system has a life bearing planet. That we're pretty uncolonized would imply certain things.
But it's probably just space dust or something. A shattered planet could be pretty cool too.
It could be the former, although science is going fast there is still no realistically plausible (let alone implemented) method of getting Faster Than Light travel. Even in thousands more years there might never be. In which case its entirely possible that the universe has lots of planets with sentient life on it but has not been colonised because the entire concept of colonisation in practice is implausible and just not worth it.
Hey, I was going to post that! Or they're already here, secretly, as shapeshifting reptillians.
But without FTL travel I don't think colonisation is practical unless you're approaching the death of your sun. Hell, I expect humans to terraform the rest of the solar system first, and even that is quite a feat.
Keep on keepin' the beat alive!
Assuming KIC[numbers] *is* their home system, not some outpost on their frontier.
I don't think we need to worry about being colonized per say, because why bother, but what if they show up in our system, and start building a dyson swarm round the sun? We'd be like "uh, excuse me, do you mind? We're fucking using that" but they don't hear because they only perceive the upper 6 dimensions or some shit.
Alternatively, if they are only in their own system that kind of implies things like the alcubierre drive are a wash which is pretty meh.
When the sky above us fell
We descended into hell
Into kingdom come
Outpost or not, if they're starting to construct a Dyson sphere before they've run out of places to colonize it would mean that FTL travel is at least impractical. It has to at least be harder to shift population to other places with easy energy & resources than to build megastructures to support them.
To be clear, a dyson sphere (shell/swarm) as originally conceived isn't for living on, it's for harvesting energy.
And not necessarily; constructing one of those beasts could simply how they generate enough energy to travel between stars. Alternatively, they could just find constructing fuckhueg space structures more efficient than terraforming worlds, or perhaps they have cultural reasons why they don't like terraforming and prefer to leave the planets they find in their natural state (this is actually the official position of NASA). Or maybe it's a vanity project? Or maybe it's simply some artefact of their technology which is beyond our comprehension (just think how you'd explain what you do for a living to someone from 500 years ago).
IDK, if we found an Earthlike around Alpha Centauri, I think we could put a colony there inside a couple of centuries if we put our minds to it and perhaps four if we don't; with currently existing technologies we could get there inside a century and with conceivable future technologies I think we could get there in just south of a decade.But without FTL travel I don't think colonisation is practical unless you're approaching the death of your sun. Hell, I expect humans to terraform the rest of the solar system first, and even that is quite a feat.
Meanwhile, IMHO terraforming is overrated. You can change a worlds atmosphere, you can add oceans, you can (somehow, I guess) find a way to give the world a magnetic field to keep people on the surface from being overly irradiated but you can't add mass to the planet and give it anywhere close to the 1g we evolved to live in. We know that microgravity causes all kinds of health-complications in astronauts from loss of muscle and bone mass to vision damage and god knows what else; all easily manageable with trips measured in months but people living our their lives in low gravity? Being born in low gravity? Obviously, the 0.4g on (say) Mars isn't going to be as bad as what the astronauts experience on the ISS but I think there's a good chance we're going to see health-complications for any permanent Martian population. "Come Live on Mars, die sooner" < not a winning slogan.
Oh, and the other terrestrial worlds have way less gravity than even Mars. Only Venus is really suitable for terraforming. And Venus needs a lot of work doing to it.
Is that really any more impractical than just... popping to Alpha Centauri, Barnard's Star, Sirius if we happen to find an Earthlike around one of them?
When the sky above us fell
We descended into hell
Into kingdom come
Yes, I know. I was assuming it was a swarm of solar panels supporting people on a planet or maybe culture orbitals or something, not an actual sphere being built in bits.
I was careful to always say "impractical" and not "impossible". If they need to build a dyson sphere to get the energy to send out spaceships, moving population via spaceship is probably impractical. If it weren't, they'd probably just spread out instead of getting all their energy from a single star. They're not going to have large-scale FTL.And not necessarily; constructing one of those beasts could simply how they generate enough energy to travel between stars. Alternatively, they could just find constructing fuckhueg space structures more efficient than terraforming worlds, or perhaps they have cultural reasons why they don't like terraforming and prefer to leave the planets they find in their natural state (this is actually the official position of NASA). Or maybe it's a vanity project? Or maybe it's simply some artefact of their technology which is beyond our comprehension (just think how you'd explain what you do for a living to someone from 500 years ago).
I think NASA was giving about half a metric ton of mass-energy for a warp drive? A dyson sphere might be a reasonable investment for starship construction if starships are prohibitively expensive, and for some reason your civilization really needs/wants them anyways.
On vanity projects, it seems unlikely. The main reason is that for it to be a vanity project that would imply a pretty massive civilizational level of power, and it's hard to believe that they'd be confined to one system with that level of power if travel to other systems weren't extremely throttled somehow. There's a good chance they'd at least send out slowboats by the time they started building stellar scale monuments to themselves. There's a limit to how widespread they can be if this is the first time we've detected them. Not impossible that it's a vanity project, just unlikely IMO.
Basically what I keep getting at is that if that actually is bits of a megastructure or some other result of intelligent life we're seeing, then influencing the universe on that scale without colonizing the galaxy first implies some sort of throttle on colonization. An attitude-based throttle (some sort of prime directive type thing, like what you suggested) would work. We should probably expect to be in the same boat as them either way though - that they're that far developed and haven't colonized the galaxy means that there's very likely good reason for that.
Sorry dude.
Well, this may be a bit like the ancients looking at nuclear weapons and all the cost and energy that goes into producing them (imagine the cost of a single device would by easily equal to the GDP of several medieval European kingdoms, if not way more), and wondering "wouldn't it be cheaper to just send an army to massacre the population?" I mean, yeah, technically, it would... but you're not fully appreciating the context in which these things are actually being built.I was careful to always say "impractical" and not "impossible". If they need to build a dyson sphere to get the energy to send out spaceships, moving population via spaceship is probably impractical. If it weren't, they'd probably just spread out instead of getting all their energy from a single star. They're not going to have large-scale FTL.
We don't actually know that they're confined to one system. We've just seen them in one system, it doesn't mean they aren't in others where we haven't seen them. We only saw them here, assuming we saw anything at all, because they were undertaking a vast construction project, they could be in literally 100s or 1000s of star systems where they haven't done this yet (as of 500 BC) and we wouldn't see shit.On vanity projects, it seems unlikely. The main reason is that for it to be a vanity project that would imply a pretty massive civilizational level of power, and it's hard to believe that they'd be confined to one system with that level of power if travel to other systems weren't extremely throttled somehow. There's a good chance they'd at least send out slowboats by the time they started building stellar scale monuments to themselves. There's a limit to how widespread they can be if this is the first time we've detected them. Not impossible that it's a vanity project, just unlikely IMO.
In fact, no - even if they have done this a few times we still might not see it. It took some guys taking a close look at data from this one star and then writing a paper about it for us to notice something weird was going on there. We've catalogued millions of stars which might mean 10s or 100s of thousands of stars in the area of space where this hypothetical race might theoretically hold sway. Have we looked at all of them for weird dips in starlight? I'm betting no.
Maybe they're doing it right now. The period of time between "single planet civilisation" and "has colonized the galaxy" is probably millions of years, especially if they're doing so via STL.Basically what I keep getting at is that if that actually is bits of a megastructure or some other result of intelligent life we're seeing, then influencing the universe on that scale without colonizing the galaxy first implies some sort of throttle on colonization. An attitude-based throttle (some sort of prime directive type thing, like what you suggested) would work. We should probably expect to be in the same boat as them either way though - that they're that far developed and haven't colonized the galaxy means that there's very likely good reason for that.
That said, you may well be right; the seeming lack of intelligent life kicking around the galaxy is puzzling and none of the explanations I have heard sound compelling to me. It seems we're missing an important piece of the puzzle. Perhaps advanced civilisations come to understand the physical universe in ways that simply make spreading out like that irrelevant.
When the sky above us fell
We descended into hell
Into kingdom come
I get where you're coming from, but first of all you're relying on the big if that a possibly earthlike planet exists relatively near us. But wouldn't it also be be very likely that such a planet would still not be exactly like earth, and require similar terraforming as, say, Mars would, and have the exact same problems you've described here in addition to the problems of getting there in the first place, and the additional problem of getting the resources there to do this? So yeah, I do think terraforming in our own system is likely to happen first because you would need it as a step to go to another galaxy.
And I thought the majority of the issues you've described are due to weightlessness, and would be significantly reduced (or even absent) at low gravity as opposed to (almost) none, and IIRC most proposals for centrifuge like stations aimed for a lower artificial gravity than earth's. Then again, I don't think we know much about this at all right now so it's mostly speculation, and there's likely problems we don't know about yet. Which, I suppose, would be easier to test on a nearby planet instead of flying to another solar system and hope it will be okay (not to mention the health problems of a decade long space flight). Optimistically people would simply adapt to their home planet, and as long as you don't travel you'll be fine. Babies born there might even be better adapted (though have bigger problems returning to earth), with an emphasis on 'might' because it might also be impossible to give birth to a healthy baby under the circumstances. And again, is it that likely that the coincidental nearby earthlike planes are exactly like earth and won't have these problem toos?
Also your gravity claim is untrue, the other terrestrial planets do not have "way less" gravity than Mars. There's only Mercury, which has almost identical surface gravity (0,38g instead of 0,376g, so actually marginally bigger), and Venus, which is closer to Earth at 0,905g. Unless you meant minor planets and moons, which are indeed a lot lower.
Anyway, talking about why they haven't reached us yet, your post describes it might be possible to colonize a near star, 1,500ly away is quite a lot more and might simply be impractical without FTL technology.
Keep on keepin' the beat alive!
I forgot to write that I think artificial habitats are a more realistic prospect for human space habitation than living on planetary surfaces, in this or any other system.
P.S. if you put engines on a space habitat now it's called a generation ship.
I think the idea of a permanent presence on Mars al la Antarctica (these places have quite a lot in common actually) is a good idea, I just don't think a proper colony with people being born, living out their lives and dying there is viable - unless I'm wrong about the gravity thing, which I'm very happy to be.And I thought the majority of the issues you've described are due to weightlessness, and would be significantly reduced (or even absent) at low gravity as opposed to (almost) none, and IIRC most proposals for centrifuge like stations aimed for a lower artificial gravity than earth's. Then again, I don't think we know much about this at all right now so it's mostly speculation, and there's likely problems we don't know about yet. Which, I suppose, would be easier to test on a nearby planet instead of flying to another solar system and hope it will be okay (not to mention the health problems of a decade long space flight). Optimistically people would simply adapt to their home planet, and as long as you don't travel you'll be fine. Babies born there might even be better adapted (though have bigger problems returning to earth), with an emphasis on 'might' because it might also be impossible to give birth to a healthy baby under the circumstances. And again, is it that likely that the coincidental nearby earthlike planes are exactly like earth and won't have these problem toos?
I did.Also your gravity claim is untrue, the other terrestrial planets do not have "way less" gravity than Mars. There's only Mercury, which has almost identical surface gravity (0,38g instead of 0,376g, so actually marginally bigger), and Venus, which is closer to Earth at 0,905g. Unless you meant minor planets and moons, which are indeed a lot lower.
I'm not so sure. If you can go 0.8 or 0.9c with some futuristic proposition drive then I think the time dilation gets to the point where the travellers should live to see their destination. The logistical challenge for going to nearby stars is the same as the one for going to distant stars; you just need to be able to build a ship that'll keep people alive for years or decades.Anyway, talking about why they haven't reached us yet, your post describes it might be possible to colonize a near star, 1,500ly away is quite a lot more and might simply be impractical without FTL technology.
But you wouldn't be expanding your own civilisation that way, just starting new ones.
Your other option is you colonize nearby habitable exoplanets, wait a couple of centuries until they're supporting developed cultures of their own then *they* send out colony ships to worlds near to them and so on and so on. After a few million years of this, your dudes are probably on a significant %age of the milky way.
When the sky above us fell
We descended into hell
Into kingdom come
Well, they could know about us, but not have any means of doing anything about yet. 1500ly is a damn long way to send a transmission or a weapon of any kind.
They could be doing the 'Don't broadcast, and maybe we won't get noticed' strategy.
Brevior saltare cum deformibus viris est vita
I wouldn't expect a communication or annihilation attempt. Earth is pretty obviously life bearing, but I don't think aliens that far away would have any way to know there was sapient life here. But all indications are that life bearing planets should still interesting in this galaxy, and their lack of presence suggests that a visit is impractical even for them.
1500 LY is probably too far away for us to tell if they're broadcasting anything or not. Any transmission that isn't point-to-point would be extremely weak by the time it got to us. I doubt we'd be able to notice any signal they weren't intentionally beaming out to us.
The other implication if that were an actual alien race would be that it'd suggest the Great Filter is still ahead of us.
I find the assumptions behind the theory of a Great Filter deeply flawed. There is an assumption that life would both be able to spread through the universe and would want to.
While self-replicating machines etc could be created, what would be its purpose? Life spread across Earth because it was to the advantage of those alive then, what immediate purpose does it serve to send out self-replicating machines that would never return home?
As I said, the very notion of universal colonisation could be false. If FTL travel is impossible then colonisation may be implausible. In which case there may not be a Great Filter as sentient life could be abundant throughout the universe but undetectable to us.
So, if they're so superior why don't they get used in any conflicts? In fact, they must be inferior to our conventional weapons because we never use them. Right?
It's unlikely that they're the first. If there are two sapient races, then there are almost certainly many. If the reasons are political or cultural, then you need to assume that all races have political or cultural reasons not to do it. I consider this unlikely, but if it were true there's no reason to assume we'll be any different at that stage. The difference between this and assuming that there is some logistical reason not to do it is negligible right now.
I think the assumption here that I have an issue with is that the cost-benefit analysis of total colonisation vs limited colonisation vs megastructure buidling is uniform across all of time and space. Just because it makes no sense for them to do it now, in this part of the universe doesn't mean it won't make sense for them, us, or someone else, to do it at some other point in time or some other part of the universe.
The assumption is also that regions of space, once colonised will stay colonised more or less indefinately.
This is that massive coincidence again, though. On further reflection of the likelihood of this, I can only pray that this isn't the case. For colonization to be worth doing, and for it to not have happened until now, and for sapient life to be so common that two races could coexist so close in time and space, it won't matter how far off their expansion horizon is from us - we are almost certainly thoroughly fucked. The Great Filter will be ahead of us, and it is going to be angry.
The Great Filter will learn to *fear* us.
This is solved by a version of the anthropic principle. Our conversation here is nothing special. I could be having a similar conversation on some other forum, or with someone else. If you weren't here, I'd probably be doing something equivalent with EyeKhan. Right now, other people besides the two of us are probably having similar conversations. Nothing is special about what we're doing right now, so it's a believable outcome.
I am trying not to be offended here.
The same cannot be said about the idea that they exist, are colonizing the galaxy, but haven't gotten to us yet. That would place both us and them in a privileged position in the history of the galaxy. It's not impossible, but it's extremely unlikely, only more so because the galaxy has been capable of supporting life such as our for billions of years before now.
The situation can only be resolved by assuming there's nothing special about our situation. We aren't privileged. If we had existed at some other time in the the past or next billion years instead, or in some other galaxy, we would still be able to look out and see most stars empty, with a scant handful stars having megastructures built around them. The only way this can be true (if that is a megastructure we're seeing), the only way to maintain our unprivileged status, is if interstellar colonization just isn't a route civilizations go down, for whatever reason. Otherwise, the universe doesn't meet what we should expect as unprivileged observers.
Alternative theories:
* if life on Earth began elsewhere that would potentually add billions more years to the timescale of the evolution of life meaning that it is only around now that intelligent life begins to develop
* Once intelligent life is advanced enough, it stops expressing itself in ways which are detectable to us
It actually doesn't, the point of it is to escape uniformity of motive. If galactic colonization is not merely inconvenient, but has intractable problems of some sort which throttle it, societal motivations don't matter - it's just not going to happen much, or maybe ever depending on the nature of the problems and how parallel universal sapient development is. One possible solution is that building something in your own star system is just so superior to colonizing the galaxy that nobody ever really gets too far from their home systems before just doing that instead.
The problem I have with this is that intersteller colonisation is plausible even with current or near future technologies (although not easy); certainly more plausible than megascale engineering, so it's hard to imagine what would keep civilisations from doing it *across the board*; especially when some races may find it a lot easier than we do - if they're on a world with lower gravity, getting into orbit isn't such a pain in the ass, races longer lived or less suseptable to radiation damage would find space travel a lot easier etc. I mean, space travel is hard but not that hard.
The bottom line is that if that actually is an alien civilization building a megastructure, their existence implies that it is very unlikely that interstellar colonization is something we'll ever actually do, even if we don't understand the reasons yet. If we look closer and find out that they are colonizing systems even while building this thing, that they're expanding outwards in a manner consistent with eventual galactic colonization within the next hundred million years or so, then we'd better hope that galactic colonization actually is a terrible idea and we just managed to spot them before they figured it out themselves and stopped completely. Otherwise that implies that there's a very high probability that oh shit oh shit oh shit fuck fuck fuck fuck fuck.
Alternatively, a species rate of technological progress is no constant; after a certain point you reach more of a plateau and we'll catch them up before they get near us.
When the sky above us fell
We descended into hell
Into kingdom come
They are being used, they're just not being detonated. They cannot possibly be replaced by swords, no matter how big - swords just can't hope to accomplish the same things.
Also, I was trying to steer it towards "bombs" and not just nukes because you really need to see the full suite of what were doing instead of medieval weapons for the comparison. But we're already pretty far off track here now.
If it's ever a good idea, then in a high sapient population universe (which there mere existence would imply - one species might be an anomaly, but two so close implies many about), then colonization should have already been done to death. We're also at least 4 billion and probably closer to 8 billion years late to the party - the universe should be packed if colonization were the way to go for anyone at any time. Once colonization starts, it should be virtually unstoppable, because once one system successfully sends out colony ships, now you have many systems with the tech to colonize the stars and they all have proof that it's a good idea.I think the assumption here that I have an issue with is that the cost-benefit analysis of total colonisation vs limited colonisation vs megastructure buidling is uniform across all of time and space. Just because it makes no sense for them to do it now, in this part of the universe doesn't mean it won't make sense for them, us, or someone else, to do it at some other point in time or some other part of the universe.
The assumption is also that regions of space, once colonised will stay colonised more or less indefinately.
Maybe some disasters will locally wipe out some populations, but on a cosmological scale then yes, once a region becomes colonized it should stay colonized until that becomes impossible (probably the degenerate era). Otherwise, this implies that races never get more than one or two steps outside of their star before somehow dying out totally, leaving nobody to recolonize. That isn't substantially different from no colonization at all.
The first one seems pretty unlikely, as if intelligent life were only now emerging into the universe but was doing so in large numbers it would mean we're one of the first races out of the gate. It would mean there's nothing special about our evolutionary history, except that we were faster at it than most. I guess maybe it's true, but damn that'd make us incredibly lucky. This also seems to go against what I know of evolutionary history - there were a couple big leaps that had to get made, and it should have been just chance that made them take as long as they did. There should be races far luckier than ours even if all/most life comes from panspermia.Alternative theories:
* if life on Earth began elsewhere that would potentually add billions more years to the timescale of the evolution of life meaning that it is only around now that intelligent life begins to develop
* Once intelligent life is advanced enough, it stops expressing itself in ways which are detectable to us
I can't come up with any strong objections to the second at the moment, as it's stated.
Some could leak out of their systems, as long as they figure out that it's a mistake before they get too many generations into it. If it stays a good idea in the long term for even one civilization, we get back to the problem of how the galaxy should be filled, but if colonization is anomalous whenever it happens, a mistake that gets fixed or contained, then we can have a populated galaxy with our system still being uncolonized.The problem I have with this is that intersteller colonisation is plausible even with current or near future technologies (although not easy); certainly more plausible than megascale engineering, so it's hard to imagine what would keep civilisations from doing it *across the board*; especially when some races may find it a lot easier than we do - if they're on a world with lower gravity, getting into orbit isn't such a pain in the ass, races longer lived or less suseptable to radiation damage would find space travel a lot easier etc. I mean, space travel is hard but not that hard.
It's not them I'd be afraid of. It's whatever the thing is that keeps killing off other technological species before they can catch up to where those guys are right now. If they are anomalous, we can't count on being as lucky as them.Alternatively, a species rate of technological progress is no constant; after a certain point you reach more of a plateau and we'll catch them up before they get near us.
Distant observers (in space or time) would not have access to the full suite of what we are doing, just like we don't have access to the full suite of what the KIC guys are up to.
We *are* one of the first races out of the gate; the universe is only 14 billion years old and most models of the ultimate fate of the universe have it remaining this way for at least tens of billions and possibly trillions more. Assuming those models are correct, we're in a very young universe.The first one seems pretty unlikely, as if intelligent life were only now emerging into the universe but was doing so in large numbers it would mean we're one of the first races out of the gate.
It doesn't necessarily make us the first or even close to the first, it just lowers the amount of time in which other intelligent races can potentially have been kicking around out there quit drastically (from billions down to millions); therefore potentially explaining the lack of evidence we see for them.It would mean there's nothing special about our evolutionary history, except that we were faster at it than most. I guess maybe it's true, but damn that'd make us incredibly lucky.
The more I think about it the more sense it makes, our science has already begun shown us that the reality we perceive in our day to day lives and the reality as it actually exists are not the same thing, and questions such as why the universe exists and is the way it is are currently completely beyond us; it makes sense that as a civilisation advances in knowledge over a period of millions of years they will come to understand our reality in ways we cannot even comprehend and will, presumably, also develop technology anchored in that understanding.I can't come up with any strong objections to the second at the moment, as it's stated.
An related idea is that intersteller colonisation *is* a good idea until you reach a certain point of development at which point it stops becoming a worthwhile endeavour. This may happen in fits and starts. For example:Some could leak out of their systems, as long as they figure out that it's a mistake before they get too many generations into it. If it stays a good idea in the long term for even one civilization, we get back to the problem of how the galaxy should be filled, but if colonization is anomalous whenever it happens, a mistake that gets fixed or contained, then we can have a populated galaxy with our system still being uncolonized.
* Interseller colonisation is current theoretically possible but very expensive so not worthwhile
* Technology develops; now it's worthwhile because it's cheaper and we're running out of living space
* A few hundred years later and now technology has developed to the point where we can build things like Halos/Culture orbitals and other elaborate megastructures to live on, so we don't need to expand into other stellar systems for more living space; we still do it sometimes just for the hell of it but there's no massive push to expand as there was in previous eras and expansion slows to a crawl
* Thousands of years later our society is so fantastically advanced we now need dyson spheres to meet our energy needs so we have to start expanding other stars again to meet our resource needs.
* Perhaps a million years on we're now so advanced we can now manipulate reality itself and everyone just moves into the giant Tardis we made
When the sky above us fell
We descended into hell
Into kingdom come
Looked at that way, sure. But I meant that it's been billions of years since life such as ours should have been possible. Our star formed a few billion years later that a star like it could have, and we took a couple billion years longer evolving than we theoretically could have. So if sapient life is common, then there should be races in the galaxy with a couple billion years head start on us, more than enough time to fill it at even a sluggish pace.
A singularity or a vastly different way of life would probably be a perfectly good reason not to head out into the stars. Why colonize the galaxy when you can hop into a pocket universe instead, or you're all uploaded to an infinite capacity mainframe housed in a microsingularity, or you can make TARDISes arbitrarily bigger on the inside? Or some explanation that no human is even capable of thinking of.The more I think about it the more sense it makes, our science has already begun shown us that the reality we perceive in our day to day lives and the reality as it actually exists are not the same thing, and questions such as why the universe exists and is the way it is are currently completely beyond us; it makes sense that as a civilisation advances in knowledge over a period of millions of years they will come to understand our reality in ways we cannot even comprehend and will, presumably, also develop technology anchored in that understanding.
For the record, I wrote my TARDIS example before I read yoursAn related idea is that intersteller colonisation *is* a good idea until you reach a certain point of development at which point it stops becoming a worthwhile endeavour. This may happen in fits and starts. For example:
* Interseller colonisation is current theoretically possible but very expensive so not worthwhile
* Technology develops; now it's worthwhile because it's cheaper and we're running out of living space
* A few hundred years later and now technology has developed to the point where we can build things like Halos/Culture orbitals and other elaborate megastructures to live on, so we don't need to expand into other stellar systems for more living space; we still do it sometimes just for the hell of it but there's no massive push to expand as there was in previous eras and expansion slows to a crawl
* Thousands of years later our society is so fantastically advanced we now need dyson spheres to meet our energy needs so we have to start expanding other stars again to meet our resource needs.
* Perhaps a million years on we're now so advanced we can now manipulate reality itself and everyone just moves into the giant Tardis we made
This actually works I think. As long as colonization has constraints, it'd fit without resorting to low-probability scenarios while still allowing relatively common sapience.
I don't have an answer for the Fermi Paradox, but I think many of you are vastly overestimating the ease with which we could establish an interstellar colony. Current propulsion technologies just aren't really good enough to move anything of substantial mass such a long distance - especially since we'd need to slow down at the end. There are fundamental limits based on the energy density of our currently available fuels. Sending enough technology to establish a self-sustaining habitat in an unknown and likely hostile environment isn't just expensive - it's damn near impossible with our current level of technology. There's a tradeoff here - you either need vast resources to keep a generation ship alive, which dramatically increases the weight of your payload, or you need very high speeds, which isn't practical for anything but the smallest of payloads.
That's ignoring the fundamental issues with technology mooted by Vinge and others - to set up a high-technology society at interstellar distances you need a surprising amount of stuff and population. This isn't Mars, where we could imagine robotic ships providing a regular supply of high technology goods to keep things going. This is at distances so far that everything needs to be self-sustaining - from materials sourcing to purification to manufacturing to repairs. It requires a lot of people and a lot of equipment. Some people have tried to estimate just how much population would be required to support our current level of technology on Earth, and the numbers are often in the tens of millions. Even if you ruthlessly cut this number down by eliminating positions of marginal importance, you still need an enormous critical mass, especially given the challenges posed by the (likely) hostile colonial environment (which eliminates the possibility of establishing a low tech colony). One could imagine technological breakthroughs in robotics, AI, and nanotechnology that might address this issue, but for now those technologies are science fiction. Self-perpetuating technology simply doesn't exist.
If propulsion gets dramatically better, it will at least be feasible, even if ruinously expensive, to set up a colony. But absent a lot of other fundamental shifts in technology, there's no way it's going to appear to be worth it.
"When I meet God, I am going to ask him two questions: Why relativity? And why turbulence? I really believe he will have an answer for the first." - Werner Heisenberg (maybe)
Forgot to reply earlier, but:
Regarding the gravity thing, obviously it's all unknown at this point. But from what I've read, most designs for, say, rotating spacecraft, aim for a much lower gravity and it's assumed/hoped that this will be enough. Most problems come from a lack of gravity (fluids not going to the proper places etc.) and are thought to be much less of a problem if you have at least some gravity. But of course this has not been tested yet. Obviously an Antarctica like base would also come before any actual colonization. But still, any problem you'll encounter trying to colonize other planets in our solar system are likely also encountered on exoplanets (unless you're extremely lucky and find a copy of Earth nearby), so I think it makes sense to try it here first. If you can do it here, you might be able to do it in another solar system. but if you can't even do it here, where the distances are relatively short and there's at least some prospect of direct aid, or even evacuation if it all goes wrong. So I think colonization in our solar system is basically an essential step to colonizing exoplanets. And even if you don't want to go terraforming and colonizing planet surfaces, you probably still want to try it out in nearby space before flying to the next solar system with nothing more than hope to try and make it.
And again, that big 'if' in 'if you can go 0.8 or 0.9c', it's a big if to speculate about future propulsion. I'm a bit rusty on time dilation etc. so I'm not sure if you're correct on that.
Lastly, if you're not going to expand your civilization but starting a new one.. Bluntly put, would a society be willing to pour vast resources into a project like that, which does not have any added benefit for their own civilization? Sure, it'd be cool, but would that warrant the presumably vast expenses? The Apollo project took NASA funding to almost 5% of US budget, but at least had direct benefit and prestige in the cold war.
Keep on keepin' the beat alive!
Astronauts on the ISS currently do 6 months tours in microgravity and this is enough for noticeable but not serious health effects. For spacecraft that produce gravity, but lower than earth's, will presumably mitigate health problems to the extent that missions measured in years will be possible without astronauts suffering too badly. But over the course of human-life time, I believe there is a good chance that 0.4g is going have an impact on people living on Mars and people born on Mars. No one will want to go and live and have children on Planet Osteoporosis.
Here's the thing: I don't think any space colony has a hope of being sustainable unless it has a genuine economic reason to exist; after the first few generations the population will just drift away otherwise. "to try it out for when we do it on exoplanets" is not a genuine economic reason; the people are there for the sake of being there, not because there's some advantage to being there. I don't say such a thing couldn't or shouldn't happen, I can picture NASA or someone doing exactly that, a little model community on Mars made up of volunteers to study long term effects of life on Mars on human beings. But that wouldn't be a true, self-sustaining colony that could survive if something bad happened to the Earth.Obviously an Antarctica like base would also come before any actual colonization. But still, any problem you'll encounter trying to colonize other planets in our solar system are likely also encountered on exoplanets (unless you're extremely lucky and find a copy of Earth nearby), so I think it makes sense to try it here first.
Society isn't a monolith. Some entities in society made decide they just don't like the way things are being run around here (here = Sol) and take off in a generation ship.Lastly, if you're not going to expand your civilization but starting a new one.. Bluntly put, would a society be willing to pour vast resources into a project like that, which does not have any added benefit for their own civilization? Sure, it'd be cool, but would that warrant the presumably vast expenses? The Apollo project took NASA funding to almost 5% of US budget, but at least had direct benefit and prestige in the cold war.
When the sky above us fell
We descended into hell
Into kingdom come
I always got the impression that a lot of the biggest problems with lower gravity stem from expecting the astronauts to return to Earth. If there's no such expectation, then it's not as big a deal if you adapt to lesser gravity.
A Martian space elevator can be built with currently existing materials.Here's the thing: I don't think any space colony has a hope of being sustainable unless it has a genuine economic reason to exist; after the first few generations the population will just drift away otherwise. "to try it out for when we do it on exoplanets" is not a genuine economic reason; the people are there for the sake of being there, not because there's some advantage to being there. I don't say such a thing couldn't or shouldn't happen, I can picture NASA or someone doing exactly that, a little model community on Mars made up of volunteers to study long term effects of life on Mars on human beings. But that wouldn't be a true, self-sustaining colony that could survive if something bad happened to the Earth.
Totally agree that new colonies won't survive without an economic reason to exist. We don't want Space Detroit.
When I say it's "we could start a colony at Alpha Centauri with current or conceivable technology", wiggin, what I mean it is not actually physically impossible for us to do it, not that I think such an undertaking is likely or even a good idea.
If aliens showed up tomorrow and issued an ultimatum: "This is getting ridiculous now; If don't at least have a colony on Alpha Centauri by 2200 we're going to exterminate you. You're making the whole galaxy look bad." and we just devoted like 25% of the entire planet's GDP to making it happen, it could be done. That's what I mean, not that I think a project like that would happen under any realistic economic and political constraints.
But the fact that it's a theoretical possibility even now has implications for assessing how difficult it it would be for a vastly more advanced society than our own.
The other caveat is that it all rather depends on the presence of an Earthlike planet within approximately 20 lightyears with a reasonably non-hostile biosphere. No point going to Alpha Centauri to colonize a hellhole when we have so many hellholes much closer to hand.
I can't really envisage a future where we get vastly better propulsion but all other technologies stay exactly the same. Now *that* would be science fiction, which is a genre where, apparently, future societies have mastered the reality bending physics of FTL travel, and the engineering challenges involved in constructing miles long space warships but everyone's day to day lives are more or less identical to the present day, perhaps even absent day to day conveniences like smartphones or the internet. (Somewhat off-topic but it's a pet peev so fuck it)If propulsion gets dramatically better, it will at least be feasible, even if ruinously expensive, to set up a colony. But absent a lot of other fundamental shifts in technology, there's no way it's going to appear to be worth it.
When the sky above us fell
We descended into hell
Into kingdom come