Where Does Stephen Hawking Think We Can Go?
Posted by Karl Withakay on August 11, 2010
Stephen Hawking thinks we need to start looking for another home– not necessarily a replacement, but a summer home, perhaps. He says our existence is fragile enough that we shouldn’t put all our eggs in one basket and that we need to hedge our bets by spreading humanity to other worlds, just in case something happens here.
I admit that we face all sorts of threats, both from ourselves flirting with disaster and from the universe potentially trying to kill us as well. Hawking cites climate change, and nuclear or biologic war as man made threats to humanity. We also face threats we have little power to influence, such as an asteroid impact or a gamma ray burst aimed right at us.
Hawking says “It will be difficult enough to avoid disaster in the next hundred years, let alone the next thousand or million”. So what are our options, really? I’ve already covered the relative implausibility and impracticality of interstellar space travel in a previous series of posts (here, here, and here), and we’re not talking about a little exploration scout ship here, we’re talking about an big, massive ark. It’s arguably questionable whether we would ever have the resources to reseed ourselves on a planet orbiting a distant star if we somehow managed to find one suitable enough to relocate to. Certainly in the 200 year time frame, we have to think more locally. We’re talking Mars or one the large moons of the solar system. Saturn and its moons are a long way out, and the amount of sunlight that reaches Saturn is about 1% of what reaches Earth; that’s not exactly a good setup for a self sustained civilization with no support from the potentially destroyed Earth. Jupiter is a little closer, but the Jovian system still gets only 4% the solar energy Earth does and 3 of the 4 large moons are bathed in high levels of radiation due to Jupiter’s magnetic field to boot. As Mercury is too close to the sun, and Venus is pretty much worse than we could hope to make Earth by ourselves, this leaves the Moon or Mars as the most likely candidates. Mars gets about 44% the solar energy Earth does, and that’s likely enough to use to provide energy and grow crops, plus it has water and a (very) thin atmosphere. It has no magnetic field to protect against cosmic rays , but we’ve got to work with what we have.
But, how practical is creating a reservoir of humanity on mars or the moon? We’re not talking about a base or an outpost, we’re talking about a fully self sustained, independent colony here that has to be able to survive on its own. It has to support a large enough population to provide sufficient genetic diversity to allow our species to survive, at least 1000 people, and it probably needs to be able to grow. Sure Mars has water and solar energy, and with those two things, you can also have oxygen, but how independently habitable can you make it within 200 years? How bad would the devastation to the Earth have to be before Mars was more survivable than Earth? You either have to terraform Mars to make it earthlike enough to support an agrarian civilization , or build an entire self contained infrastructure capable of supporting itself without any support or resources from Earth. Frankly, if an extinction level asteroid hits the Earth in the next 200 years, my money is on the people who stay behind on Earth; they’ve got a lot more to work with. A devastated Earth is probably a safer bet than Mars. If we had the resources and technology to terraform Mars enough to make it habitable independent of technology (technology requires infrastructure over the long term to keep it going), we’d probably be able to neutralize global warming and clean up all the pollution to boot here at home.
Any refuge inside the solar system only works for Earth specific disasters anyway. Everything in Phil Plait’s Death From the Skies after chapter one would be just as bad for any other location in the Solar System as it would be for the earth, and I’ve previously covered that I don’t consider interstellar travel particularly likely or practical.
If we want humanity to survive really long term, we better hope we do find a way to get humanity to the stars. Even if we get lucky and dodge all the bullets we and the universe have aimed at us, the sun’s out to get us. In a billion years, the Earth will definitely be uninhabitable, and nine or so billion years after that, the sun will be a burned out white dwarf providing very little energy to whatever is left orbiting it at that time. However, even if we manage practical interstellar travel, we’d only be delaying our inevitable doom. One way or another, there will be an end to the universe as we know it. Whether it’s a heat death where all stars are burned out and everything in the universe is in thermal equilibrium making work or energy transfer impossible, a big rip, a big crunch, or the decay of ever proton in the universe, eventually there won’t be any place in the universe for humanity to survive. Sure, we should do what we can to stay alive, but maybe what’s really important is how we live while we are around. After all, that’s all we really can control. In the words of Phil Plait at TAM8, “Don’t be a dick.”
EDIT 8-12-10: Stephen Hawking also has expressed the thought that the possibility that we might be invaded and killed by extraterrestrials is another reason why our existence here on Earth is tenuous, but I’ve already addressed why we shouldn’t worry about being invaded by ET in the posts I cited above. (here, here, and here)
EDIT II 8-12-10: Apparently I’m not the only one who thinks colonizing other world is prohibitively impracticable. PZ Meyers has an interesting post this morning where he discusses a post by Charlie Stross that discuses the same idea of how it is just so absurdly impracticable that it is essentially impossible.