I think my solution is better because it’s far less expensive (far less mass needed to maintain frozen genetic material vs thousands of frozen/sleeping people)… for every one of your ships that could be sent out, hundreds (or perhaps thousands) of mine could be- so even if the success rate is just 1% or even less, my idea would have a greater chance of successfully spreading humanity than yours.
The only disadvantage of my idea is the psychoses that would inevitably develop from having babies and children raised by robots and computers- even if these robots and computers were soft, huggable, human-like, and used lots of media that displayed plenty of (long-dead) real humans.
This is a very tough one, given what we currently know about physics. Making wildly optimistic assumptions about energy sources (antimatter?) and rocket engines (advanced ion drive?) you still end up having to consume a troublesome percentage of the ship’s total mass as reaction mass to make the journey even once (accelerate to an acceptable velocity, then slow down at the destination).
The (very sensible) provision to allow for multiple journeys (because the originally chosen destination proves useless) will increase the mass, cost, and complexity of the ship exponentially.
Conclusion: we’ll need some new physics (e.g. a way to produce thrust without reaction mass - IOW a violation of conservation of momentum) for this to be doable.
I remember an argument I had with a roommate back in 1995. He thought science had pretty much discovered everything important, and now we’re just filling in the details.
I naturally have some problems with this view :).
When I think about what life will be like in 500 years, I imagine explaining World of Warcraft to someone from 1513. I don’t have the technical knowhow to convince someone from that time that the game is possible, and they could likely give me very good reasons why my description (“I can sit down in front of a piece of glass and move an object that looks like a mouse carved from ivory, while pressing buttons on what looks like a drastically modified printing press typeset box, and the glass will glow with internal light, creating a painting that moves in response to my movements of the ivory mouse and the typeset, telling a narrative about fantasy creatures, some of whom are manipulated by other people sitting at similar glasses in other parts of the world, but really what I’m doing is causing tiny manmade sparks to flow through certain invisibly-tiny pieces of metal and silicon, and we do it because–oh, forget it”) was impossible.
To say what our generations-distant descendants will be capable of strikes me as a wee bit hubristic. We’re only a few centuries away from the beginning of the enlightenment, and already look what we’ve done. We don’t even know what the next cognitive shift in our species will be–or if there is another one coming. Will it revolutionize technology as much as the Enlightenment did?
So your reasons look good, AtPG, but I’m not buying :).
On an interstellar trip the radiation is going to be cosmic rays, which are more or less a known constant. Unlike in system when solar flares or radiation belts are a problem.
Also: if you’re in hibernation/suspension you body’s self-repair mechanisms are as slowed down as everything else, so you need much more radiation protection. Still, enough shielding is probably a trivial problem if you can mount an interstellar journey in the first place.
That may be, but all that implies is that we are likely to get something we didn’t know was possible. But what far too many people keep believeing is not that we are likely to get some things we didn’t know were possible, but that we will get one specific thing we know to be impossible - or at least a lot of technologies we can use to do an end-run.
Aside from which, your roommate may have been closer to correct than you think. The era of big physics discoveries may well be over. The era of big scientific discoveries itself may be over.
Neither am I, but the math is high-school physics and probability and the data is stuff I’ve looked up on the web. You can do this stuff too.
Nothing is safe. Every activity has some risk associated with it. Interstellar journeys are going to be dangerous; no doubt about it. But there’s a big difference between a 1% chance of failure and a 99.9% chance.
There are some finite odds that tomorrow, a large asteroid will hit the Earth and kill all life bigger than an ant. At some point, you simply have to say that the odds of some event are negligible and ignore it.
Dark matter is not neutrinos, but it’s something like neutrinos. As such, it barely interacts with normal matter. There is at the moment a large flux of neutrinos (and probably a smaller flux of dark matter) passing through you right now. The colony ship probably won’t even have a dark matter detector since it would have to be massive (though maybe you could double-purpose the water/ice tanks). It certainly couldn’t “hit” the ship.
We actually do have a good idea of most of the variables. There are multiple very good reasons to believe that the interstellar medium has very little matter of any kind, and what matter there is is mostly hydrogen and helium gas or plasma.
As I said, there will probably be a fair amount of dust. I don’t know yet if it’s significant. I’ll see if I can find figures.
The size of the craft doesn’t matter here since it’s much bigger than the objects it might hit. The only two inputs we really need are the mass of the particle and the speed of the ship.
Not for the dust grains, as I already showed.
Let me take your side for a while. What do we need to actually have an atomic-scale energy release? A modest atomic bomb is 10 kilotons, which is 4.2e13 J. Running this through the KE equation, we get a 9.3 kilogram object.
So, clearly it would be bad news if that hit you. I can’t use my math above to show that the odds are still nil, because close to a billion 9.3 kg objects fit in the original asteroid you proposed.
But as I said, I made an absurdly conservative estimate–probably by a factor of a million or more. But showing that will require data I don’t have right now, so I can’t exclude it completely.
That said, shielding is an option. One proposal is to have your shields far ahead of the ship; perhaps held in place by laser pressure. You build them out of very thin foil, and there are many layers. When an object hits the first layer, it starts breaking apart, though without losing much energy/velocity. As it progresses through the layers, it breaks apart more and more until it forms a cone of dispersing particles. By the time the cone gets to the ship itself, it is spread apart quite widely, and the conventional shields on the ship can deal with the debris.
Of course, the forward shield is destroyed. But because it’s made of such thin foil, you can just replace it immediately, and you can keep hundreds of replacements on board. You can also recycle the remains of the shield.
The short answer is that we won’t know until we try it. But we already know a lot, and our instruments will be fantastically better in just 100 years, let alone 100k.
Well, you should. Every time you step out the door you risk your life (actually, every time you don’t step out the door, you also risk your life). The chances of it happening on any given instance is low, though, so you don’t think about it.
More importantly, the people who build this ship will be aware of probabilities. The engineers who sent men to the Moon were aware, and built in a certain degree of redundancy: for instance, the Saturn V could handle a single first stage engine loss. And they needed it on Apollo 13, because the system wasn’t 100% reliable. It couldn’t have coped with losing two engines, though, even though that was clearly a possibility. You define a level of acceptable risk and build the system to meet that.
Might not be possible. It depends on how good your sensors are. The longer the range, the more time you have, and the less fuel you have to use to maneuver. But it may not matter.
It’s not impossible that there’s a danger, and it’s something to think about. It just doesn’t look insurmountable, because there just isn’t that much matter out there, and what stuff there is isn’t that dangerous. I think I can safely say that we’ll know for sure in under 100 years.
I am not arguing in favor of the proposition “We are going to be doing any interstellar space travel.” I am arguing against the proposition “We are not going to be doing any interstellar space travel.” In other words, I certainly don’t think it’s likely we’ll do interstellar space travel, but I also think it’s awfully premature to predict that our 10,000 years from now descendants won’t figure out how to do it.
Since he said that, a fifth state of matter has been discovered, the acceleration of the universe’s expansion has been observed, the human genome has been mapped (to take a non-physics example), and the Higgs boson has been found. We’ve had less than half a century to apply the computing power of a single iPad to the study of our universe. I’ll continue taking the bet against my roommate :).
I am in a pessimistic mood today. While I agree there are going to be discoveries made that we cannot fathom today, keep in mind that all the good things you mention in your last paragraph were accompanied by developments in faster and more efficient methods for us to butcher and slaughter ourselves. All our great discoveries to come may be for naught if we cannot get a handle on our inbred savagery, purposeful ignorance, and greed.
Vinor Vinge had a similar idea in A deepness in the sky (1999) except he tacked on humans biologically adapted for space and added human longevity. Wiki: “The book discusses some of the problems of trying to maintain an interstellar trading culture without access to superluminal travel or to superluminal communication.”
The last paradigm shift was plate tectonics, during the 1960s. So accepting this premise, we have about 50 years of fully mature science to extrapolate on. How far out would you want to project forward based on that, 200 years maybe?
The Fermi paradox (1950) is based upon the ease of intra-galactic travel over 5 - 50 million year time spans. 200 << 5,000,000. Admittedly, the Fermi paradox cuts both ways: if space travel is so easy, where are the aliens?
I’m probably not able to be convinced, so I’ll certainly forgive you if you give up on trying.
I’ll respond to the above in a moment.
Folks say I’ve got hubris when I suggest that science is not the same as magic and there are actual limits on what we can do, even considering technological progress. If it simply isn’t possible to fold space then science can’t fix that. It’s not magic. If it requires more energy than is contained within a star system, then it becomes useless to us long after we master a different method of interstellar travel, and may never be useful.
This isn’t Futurama, not everything is possible if you imagine it.
To me, it takes a fair amount of hubris to suggest that we know the odds that somewhere on a several trillion kilometer journey that we will encounter an object of less than ten kilograms.
Yes, I believe it’s possible to suggest an average density of space. That’s easy math.
You’re traveling at speeds that make it impossible to steer the ship, and an impact of 10 kilograms will obliterate you. Your math suggests that matter in space is not very dense, on average. That objects such as those are going to be rare.
Except of course, for an object that was ejected from a stellar system, which the math and probabilities says isn’t even there. Because yes, it is a rare event. But like I said, it only has to happen once. And we are traveling from one star system to another. That tells me we might encounter other objects which have been ejected from a star system. And if folks are telling me they can know the precise odds of such a thing happening or not happening, I am suggesting they are placing too much trust in their ability to know the unknown.
I believe we can use observation and determine that there isn’t much of anything out there. I believe we can determine to a fair degree the mass of the galaxy. I believe we can know a lot of things that are difficult to know.
But never would I believe that, having never traveled to another star system, having never even sent a survey probe, that we could plug in the rather unrelated numbers of average matter density of space and distance traveled and arrive at a safe conclusion. That’s hubris. That isn’t what we need to calculate. You don’t just need to know how much matter there is on average. You also need to know that there’s nothing that is not-average in your way. And you can’t know that.
You might be able to tell from gravitational lensing that there’s no star or planet in your way. Yes, I can buy this. But I can’t believe that you can venture into the great unknown and suggest it is known via probability.
I think it is a lesser leap of faith to suggest we are actually bound by some of the physical properties of the world around us, and that science isn’t magical. I think it’s a great leap to think even our greatest scientists know for certain that there’s no rocks between here and the next star system, particularly when we’re finding more and more and more rocks in our own backyard all the time, that we never noticed were there.
Some things are just not calculable without some actual data. And I don’t think average density of the matter in space is enough data to state what you state with such confidence of the odds.
That’s my position. If I just can’t grasp this matter then so be it. I’m not the one you’d have to convince anyway. I’m just a random skeptic.
Worse, for such things to be discovered, it is necessary for the basis of a good deal of our current science to be overturned - not the results or products of that science (of which there are many), just their basis.
So in order for warp drives and FTL travel to come into daily use, we will also need to develop brand new explanations for how we managed to invent things like LEDs, nuclear reactors, radios, etc, whilst all the while fundamentally misunderstanding why they worked.
The problem is really just that you’re making a very strong claim–you’re saying we can’t do it, even in 100k years. What I’m suggesting is that there are no obvious showstoppers to a generation ship.
Maybe it is the case that there are a bunch of 10 kg objects surrounding our solar system. It would be very unusual since they couldn’t surround all the solar systems in the galaxy due to mass considerations, but maybe there’s something special about ours. Still, you have to make the further bold claim that we can’t possibly shield against such things, even though we already have designs that look like they would work, and even with 100k years of development.
Personally, I see a lot of reasons to think that warp drives and the like will never be possible. Our best physics says they aren’t. Generation ships don’t have this problem–so far, it’s just an engineering problem, and reasons why they* can’t* work are speculation.
Obviously, there is the chance of failure. And such ships will be expensive enough that we won’t try very often. But it’s not impossible that once we have our entire solar system’s resources at our disposal, that we can make an attempt every few centuries. Even if the first few fail, surely we will learn from those mistakes and fix them.
In short, you need better evidence before claiming that generation ships are impossible. Improbable–sure, have at it; economics seems the biggest problem to me. But impossible is a scientific claim and needs something backing it.
I don’t think anyone says what you claim folks say in that first sentence. The hubris doesn’t come from distinguishing science from magic. The hubris doesn’t come from saying there are limits on what we can do.
The hubris comes from a 21st-century person claiming to know what the limits will be on a 9,999th century person.
I think you (and I, for that matter) are only slightly better qualified to determine what those limits are than a -10th-century-person would to determine what the limits are on 21st-century people.
You observe the current state of knowledge and project it into the future. I observe the current rate of knowledge change and project it into the future. I think I’m on firmer footing.
Again, I don’t suggest that we will be able to engage in interstellar travel. I suggest it’s too early to say.
The problem with that is it’s so expensive to send anything into space and the technical challenges are so complex, those resources would be much better used right here on Earth.
You’re saying that current scientific knowledge is only slightly better than it was 1,000 years ago - I disagree, but if you’re right, I wouldn’t hold out much hope that your 9,999th century person will have fared any better.
Are you mathematically extrapolating though, or falling into the trap of making false analogies - I mean, the fact that people once had quite mistaken and uninformed views about this or that limit doesn’t necessarily have any connection at all to whether or not our views are correct or properly-informed.