Will we survive earth?
I watched a program on one of the many sciency type channels on sky today (the program was called ‘space’) It was IMO crammed with pseudo-science (fake science) but it planted a seed - It stated that humans have overcome seemingly impossible obstacles throughout history with apparent ease. Obstacles which were thought impossible before.
Will the human race survive earth and develop the technology necesary to tracel the vast distances required to find habitable planets?
Failing that, will it discover ways of using the near planets to survive for many thousands of years more?
*Will the human race survive earth and develop the technology necessary to tracel the vast distances required to find habitable planets? *
Yes. But I don’t think that finding habitable planets will be the driving force. I believe it will be a drive for resources and for exploration. I believe that habitable places will be far easier, safer and more comforatble to build (e.g. perfect gravity, temperature, & beauty, no bad indigenous bugs or folks), than finding “second earths”. Terra forming will probably also be more common than colonizing habitable planets too.
In short, do I think in 17,005 C.E. there will be a big Habitat the size of Conneticutt sized habitat (or a Babylon 5 style ship or pleasure asteroid or Dyson sphere) full of humans circling a star in the Andromeda Galaxy? Yes I do.
*it discover ways of using the near planets to survive for many thousands of years more? *
Yes. I expect that my Grandchildren will be the first generation to do this and my great grandkids to be in a society that couldn’t survive as is without the resources it harvest from the solar system
The Andromeda galaxy is roughly *2.9 million * light years from Earth. Barring some kind of superluminal propulsion (for which there are some theoretical possibilities but no conception of how to actualize them or knoe if they are even physically realizable) we aren’t going to be there in fifteen thousand years, or a hundred and fifty. Maybe in fifteen million.
But I agree that, once (if) we extend into space we aren’t going to be that interested in habitable worlds. We don’t really have any good data on the frequency of earth-like planets, but even a planet roughly the same size and in a zone suitable for us would still mostly likely lack a breathable atmosphere or be otherwise uninhabitable just as the earth 1.5 billion years ago would have been uninviting to us. As for terraforming, that would require spending an enormous amount of effort to get a relatively small return in living space. The biggest thing the planet does for us that we can’t readily build into a spacecraft or orbital habitat is act as a filter for radiation. Protection from radiation takes either extremely powerful magnetic fields–to powerful for a small habitat or ship–or a lot of mass, which the earth provides via it’s rotating iron core and thickish layer of air. By the time we have the capability to manage resources on the scale demanded by such projects, we’ll probably have no need for them, as we’ll have had to find some way to dispense with all of the extraneous plumbing and delicate tissue that serves to enclose and act as a vehicle for our intellects. Hauling around huge masses of oxygen, water, food, et cetera that we use so wastefully just isn’t feasible for long-term space habitation. (Hey, it’s not our fault. We “grew up” with such a large allowance that we never had to conserve these things.)
But it may be a long while before we have a need to leave the solar system. The resources between earth and Jupiter’s orbit alone are a wealth that Andrew Carnegie couldn’t imagine in an LSD-induced fantasy. It’ll take a long time to make a dent in those commodities, and the energy cost of traveling between stars using any conceivable technology is so high that we’ll do it not because of a need for resources (that would be cost-prohibitive to transport back anyway) but because we want to explore. There’s no predicting, or even realistically speculating on what we’ll be able to do in the future; we only know that we’ll have capabilities we can’t even imagine today, any more than Babbage would have imagined the personal computer.
That is assuming, of course, that we survive long enough to get to that point. Any number of things could happen to clean us out, including a lot of things we threaten to do to ourselves, not to mention being destroyed to make way for a hyperspace bypass.
The Earth will be around for at least 4-5 billion years when the sun goes red giant, and even then it might not be swallowed. Given that this is a similar amount of time from when life first appeared on Earth and that homo sapiens has been around for less than a mere million years, the species which survives Earth will be “us” only insofar as “we” are those first prokaryotes.
And, of course, many obstacles which haven’t been overcome yet, like flying by flapping our naked arms or travelling through the sun. It might be that travelling faster than light is similarly out of reach of any possible engineering.
We’ve actually pretty much got it already. The problem is that you can never come back, we’ve no idea where we would go, and people might have to set off knowing that it would likely be their grandchildren who actually arrived (absent any ‘stasis’-type technology).
Nothing we could possibly do to Earth will make it less hospitable than the other planets.
Every generation has probably had its share of shortsighted naysayers - like the legendary (or do I mean mythical?) patent office clerk who resigned because everything that could be invented had been invented, but the mere fact that people in the past thought something impossible that is today achievable, does not automatically guarantee that things we today consider impossible will one day be child’s play.
It simply doesn’t work that way - that stone age men never thought human flight would be achieved - and were wrong - does not give me license to wave away what we understand to be genuine technical obstacles to something like interstellar transport.
I call that the Sneelock argument - from Dr Seuss’ If I ran the Circus; “…He’ll Manage just fine; Don’t ask how he’ll manage. - That’s his job. Not mine…” and it is just a way or repackaging the Argument from ignorance
Interstellar transport may be just too hard to do - I’m not being pessimistic here, just trying to acknowledge the genuine difficulties;
-The distances between the stars are truly enormous
-The further/faster you want to go, the more fuel you must take, which is more mass to be accelerated, which requires more fuel to do, which makes the craft even more massive etc…
-Collision between your spacecraft and, say, a grain of sand at relative velocities that are an appreciable fraction of the speed of light is going to release unbelievably large amounts of energy (i.e. your ship is totalled).
-Deflecting an object to prevent a potential collision is also going to take huge amounts of energy to achieve (=more fuel you have to carry), if you even see it coming.
That’s just for starters.
Probably the most feasible method for putting humans on an extrasolar planet would be to send out multiple unmanned, autonomous probes that can reconstruct humans from scratch (intellectually and socially, as well as physically) when it arrives on a suitably habitable world, if it arrives - design the probes for very long-term survival in deep space and send them out more or less ballistically.
But then again, what would be the point? It may never work; we’d certainly never know it had worked, so what’s the point of creating a brand new, but ultimately pointless, human civilisation on some far-distant, forever-unknown planet at some point in the very far future? Why spoil the place?
We already understand the physics to move between Mars and Earth. The implementation is the question. Sure a gas core nuclear rocket is buildable on paper, but what kind of materials last in space, how do you construct it effectively, what kind of re-use is possible and how do you refuel it?
Stellar travel is harder by orders of magnitude but not impossible. I can see humanity settling amongst the stars, but I don’t see it being a close knit Star Trek, or B5, federation of states. I see it more as lonely islands of humanity.
As to Lib’s pessimism, the best way to allow new experiments in human social organization depend on getting far enough away from current governments. Then those that work can be emulated, while those that fail can be avoided. However the harnessing of the powers required to move in space and between stars will be the big test as to whether or not we deserve to. A race unable to control itself and its use of space technologies (moving asteroids, TW lasers, anti matter production, fusion rockets etc.) will eventually snuff itself out.
Step 1. Controlled fusion is generally available
Step 2. Large Kuiper Belt or Ort Cloud asteroid/comet gets colonized.
Step 3. Mine deuterium from the comet for power
Step 4. Small delta V to escape the Sun’s gravity well and drift into space.
It’s a generation ship writ large, but with no specific target in mind, but eventually they have to aim for a place to refuel. Or die out, nothing’s perfect.
I’d rather hope that classic fast ship design work but your point of a .5c proton wreaking your day is valid.
I’d like to know what kind of effective density does the interstellar medium have when you’re traveling at x% of C? You might be able to minimize the drag (impacts) by effectively design. Still gives you problems though.
We could also use a solar sail to power a spaceship out of the solar system, thus avoiding the fuel problem entirely. Now as for large distances, consider. We have a spaceship that accelerates at 10 meters per second squared, thus producing gravity equal to Earth normal. After one minute, it’s traveling at 600 meters per second, or .6 kilometers. After one hour, it’s traveling at 36 kilometers per second. After one day, you’re up to 864
kilometers per second. After a year, you reach 31,390 kilometers per second. Nine years will get you to 282,510 kilometers per second. At this point, relativistic effects kick in and you don’t age much while you cruise through the galaxy. So nine years to speed up as you leave Earth, and nine years to slow down as you approach the next star. In short, it would be fully possible to get a human being from this solar system to another one, without even having to use a generation ship. As for the collisions with space dust totaling the ship, future technology will solve that somehow.
The barriers to exploring the stars are not technological. They are primarily social. If the CEO of an American corporation wanted to spend money on a very costly space project that wouldn’t produce profit until years or decades into the future, and might never produce profit at all, the board of directors would shoot him or her down. Since corporations control almost all money in the major western countries, that inhibits space travel. Governments can spend some, but will always have trouble justifying the cost of space programs while there are more pressing problems on Earth.
In reality, the only hope for space exploration is to convince people that the dream is worth it despite the economic costs.
Our ancestors moved from being able to raft across rivers and lakes to seas and then oceans, but it isn’t the same.
a) Imagine the Phoenicians, after having gotten the hang of navigating around the Mediterranean, facing as their next-closest frontier a shoreline 4 million miles away. It’s too massive a leap of scale. Such is our situation now. We gradually got to the point the entire world was easily within our grasp and we’ve put footprints on the moon, but interstellar distances are huge and it’s very very empty out there.
b) There’s a fuel and speed problem. Those hypothetical Phoenecians could theoretically develop the technology to power some kind of craft across a 4-million-mile gap in a tolerable turnaround time. We, on the other hand, contemplating interstellar vastnesses, bump into an absolute speed limit (lightspeed) which we can’t even approach to an appreciable degree without running up against an almost insurmountable fuel-supply problem. Even if you posit new technologies like matter-antimatter annhiliation, Star Trek style, you start off with heat and heat does a lot of impressive things but doesn’t intrinsically propel you. You need thrust. You pretty much need to hurl something out the ass end of your starcraft with lots of emphasis so as to make your starcraft accelerate, so you’ve got to have on board with you some stuff to shoot out the back, whether it be rapidly-expanding hot combustion-products or steam or whatever. You’ve got to carry with you enough of the stuff to accelerate you to near-light-speed, and you’ve therefore got to accelerate your supply of stuff, i.e., it adds to the mass of your total vessel which is what you’re accelerating at any given time. Oh, don’t forget deceleration upon approaching destination. And at least during the initial explorative phases, we can’t assume there will be any opportunity to refuel or restock the expulsion-ballast or whatever we want to call it.
c) Again the Phoenicians’ situation doesn’t scale in every respect. We’re still stuck with essentially the same human lifespan. Colonization and spread works when there is a cultural continuity, a shared sense of “us”. I don’t think you’d have that when outposts are separated from each other by more than a lifetime per round trip. That draws you a very small circle with very few stars within it.
I think you’re numbers might be off a bit. After 9 years of 10m/s[sup]2[/sup] you’d be raveling at 27x10[sup]8[/sup]m/s (classic mechanics, not relativistic). That’s way too large.
It’s a question of energy ultimately. Your example of a 1 g solar sail neglects the fact that the mass of the sail requires additional area to be used, that the light falling on the sail maintains a constant intensity despite the range from the source increasing dramatically and it fails to take into account Mangetout’s points about interstellar particles hitting the ship at significant fractions of the speed of light.
For a cost perspective let’s say we need move a 100 ton ship at 1g for 34 days. The thing should be moving about .1c by then. That requires about 4.5x10[sup]19[/sup]J, or 12.5x10[sup]12[/sup] kWhrs. At 1 cent per KwHr that winds up being 125 Trillion dollars. CEOs are not holding us back.
I now eagerly await my math mistakes being pointed out.
This is only a problem if you want to travel at a significant fraction of lightspeed. It’s very possible that this could be infeasible—that the engineering difficulties we foresee today are insurmountable, or that energy will never become cheap enough to make high-speed interstellar travel practical.
But we’re talking about a timescale of several billion years before Earth becomes totally uninhabitable. The outer planets might be usable for significantly longer. Humans today aren’t willing to seriously entertain the prospect of a project that will come to fruition hundreds or thousands of years in the future, but is it really feasible that we will never advance beyond that point? That no person or organization will ever be willing and able to expend the resources to send out interstellar colonies, over a time hundreds of thousands of times longer than all recorded history?
Even making very pessimistic assumptions about the cost of a mission, it seems almost inevitable that humans will settle other star systems eventually, unless:
[list=a]We wipe ourselves out in the very near future; or[*]They’re already taken.[/list]
Technical nitpick: in a matter-antimatter reaction (say electron-positron or proton-antiproton) you get radiation. (Not having a proper reference with me I don’t know what the wavelength would be and I’m too lazy to calculate it out, but it’s definitely in the upper gamma range.) Heat is a thermodynamic term for the transfer of energy between reservoirs, or the loss of energy internal to a reservoir to the outside universe.
Radiation does have a momentum, and if you had some way of reflecting gamma rays you could use potential use the radiation itself as the propellant. A practical application of this is difficult to conceive due to the extreme energies of the radiation and by any proposal based upon extrapolation of current technology we wouldn’t be able to use more than a fraction of the energy from the reaction, but it could be that some new discovery, like magnetic monopoles, might give real capability to control and use the reaction.
If you are able to erect powerful magnetic fields, you can collect your propellant from interstellar space, in the form of free hydrogen, Bussard ramship-style. There are some serious problems with the concept; namely that a field powerful enough to collect material would kill any life form and wipe any electromagnetically stored or transmitted data right out of your computer, but if some way is found to shield against the magnetic field (which symmetry taunts us with but reality has yet to provide) then it could be feasible.
But like I said, trying to predict what will be discovered and how that will increase our capacity is a fool’s game. We have only the vaguest notions, fragments of understanding that are long yet to be unified into some kind of genuinely coherent model of everything. All we know is that it will be nothing we can imagine today.
That is, if we don’t wipe ourselves out while arguing over some petrochemical goop in the middle of a fricken’ desert. People are not know for their length of vision or patience.
Nah, we’ll never leave earth. We’ll never achieve FTL travel and we’ll never have technology advanced enough to build a ship that can actually travel several light years without critical failure.
