Originally Posted by Saquist
I don't think you understood.
Have you not seen how many impact craters there are on Earth? 25 Identifiable craters at 20 KM or more that we've been able to find... 14 of them are earlier than the Dinosaur killing asteroid. All but the BIG TOP 3 were under 100 KM. This is a very common event.
And Frankly if life is as rare as Mr. Hawking belives it to be at this intelligence level they we're really playing Russian Roulette here because it says there are a lot of life killing events our there and we've been Lucky.
Further, Hawking is not talking about just Mars, but planets ELSEWHERE in the universe or our galactic neighbor hood. Any Ex-solar Colony would have to be self sufficient...Period. That's the whole purpose in find EARTH like planets to colonize.
Biological and Nuclear War are still THE likely ways the world will end according to him because we have the technology but not the temperment. It noted that Russia and the US still have thousands of nukes in their arsenal and haven't stood down from the Cold War even today.
THERE HAVE ALREADY BEEN MANY OCCASIONS...
Where we've comes seconds to full nuclear exchange.
Oh, I know about Apophisis, and impact crators, I'm also aware of the dangers of biological and nuclear war. I live in the U.S., and I watched X-men First Class, so I know about the Cuban missle crisis. I'm also aware of the dangers of global warming, I live near the coast. I simply believe humans would survive such disasters. I think the position of humans on another planet would be very precarious. Unless, we can successfully terraform a planet like Mars and make it habitable, but that is hundreds of years off, if it can even be done. There might be some unique environmental circumstances that might prevent us from creating a long-term, stable, habitable environment, and breathable atmosphere on Mars. Scientists will first want to study Mars "as is" and learn as much about its past history, this will take a long time. Terraforming is controversial and risky, some scientists may oppose it, it will take huge political hurdles to overcome the political obstacles. Its likely the first colonizations of the Moon or Mars will simply be tiny, research outposts. Colonizing Mars is hundreds of years off, so not a good short-term solution to global warming, or nuclear war risks. As far as planets elsewhere in the universe, I don't think you realize how far off we are from that techwise. With current propulsion technology, it would take is tens of thousands of years to reach the nearest star, Alpha Centari. The humans that launched wouldn't outlive the voyage unless they could be put in some sort of stasis, like in Alien or Prometheus. We would need really well designed spacecraft that could operate independently and with minimum maintenance for tens of thousands of years. Sound realistic? No, of course not! That's why I say interstellar space travel is the stuff of science fiction/fantasy.