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Stephen Hawking - Image courtesy GrayWizard.net
We must leave this planet before we get hit by rocks or become part of a Ben Affleck movie

In a rare interview, Stephen Hawking said to the BBC that humans must move to another solar system in order to ensure the survival of the species. “Once we spread out into space and establish colonies, our future should be safe,” he said. Hawking made a similar suggestion back in June.

 

He believes that life on Earth could be wiped out by a nuclear disaster or a massive asteroid hitting the planet causing Armageddon with its Deep Impact. He said that, since we have no similar planets on our solar system, we would “have to go to another star” to find a suitable habitat.

 

Before humans could even dream of such a move, we would need to develop a viable means of transportation. Hawking proposed “matter/anti-matter annihilation” propulsion. He explained: “When matter and anti-matter meet up, they disappear in a burst of radiation. If this was beamed out of the back of a spaceship, it could drive it forward … It would take a lot of energy to accelerate to near the speed of light.”

 

Even at near-light speeds, it would take six years to reach a new star. While Hawking, 64, may not see our escape from Earth in his lifetime, he still wishes to see the planet from space.  “My next goal is to go into space; maybe Richard Branson will help me.”

 

Hawking was recently awarded the Royal Society’s Copley medal, their highest honor, for his work in theoretical physics and cosmology leading to classifications and further knowledge of black holes.

 

Lord Rees, president of the Royal Society, stated “Stephen Hawking has contributed as much as anyone since Einstein to our understanding of gravity. This medal is a fitting recognition of an astonishing research career spanning more than 40 years.”

 

In a statement issued by Hawking after learning of the award he said “This is a very distinguished medal, it was awarded to Darwin, Einstein and (Francis) Crick. I am honored to be in their company.”



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EVERYTHING IS RELATIVE
By Visual on 12/4/2006 6:17:08 AM , Rating: 2
One aspect of space travel that i didn't see mentioned in this thread, and quite an interesting one I think, is that relativity effects kick in.

No long travel times are needed...
... well, from a certain point of view, anyway.
That is, from the traveller's point of view, the journey to anywhere could be arbitrarily brief.

Open up http://www.cthreepo.com/cp_html/math1.htm and scroll down to the Long Relativistic Journeys section. Make sure you have javascript enabled. Then have fun changing the distances and acceleration. Keep an eye at the "Trip time" field...
Theoretically, even if we use the quite comfortable constant 1 g acceleration we can reach the other side of the galaxy (estimates are from 90000 to 160000 ly) in under 24 years, get to the nearest galaxies (all the ones listed at http://www.answers.com/topic/list-of-nearest-galax... for example) in under 32 years, etc...
Surprised by the results? We can go virtually anywhere in a lifetime.

On the other hand, even getting to the nearest stars is going to take atleast 3 years at 1 g acceleration. Not exactly a quick journey... so while we might not need colony ships spanning multiple generations, we still would need life-support for atleast a few years, or decades for the faraway places.

Perhaps cryogenic sleep would be the way to go?

Or... you can change the acceleration and see what happens. 10 g cuts the travel time around ten times for the larger distances. 100 g would let us cross the galaxy in 4 months... get it into the thousands, and the calculator starts to overflow and give errors, but it'd make huge journeys look like just days or minutes to the travellers.

Another interesting fact to note here, is that the "Earth time" doesn't get much different wether the acceleration is 1 g or 1000 g. A couple of years difference for crossing the galaxy. So we, with a primitive but comfortable 1 g seedship, can get there around about the same time as our superadvanced alien neighbours travelling at 1000g, if we start at the same time and distance :p

Sure we can't survive a journey at even 10 g. 1 g is the best option we can start with, it will be just like artificial gravity for the ship. I bet we can also manage slightly more than that, for example adapt to 2 g. In cryostasis we might be able to survive an order of magnitude more, but we'd never get much beyond that.

But maybe we'll find a way around this - some technology that would allow us to apply this acceleration uniformly to the whole ship, or atleast uniformly to the whole human body, so it doesn't feel the stress. Remember, you can fall even with 10000000000 g acceleration in a uniform gravity field without feeling a thing, just because it is uniform.

Ok, now a reality call of sorts. That page I showed you, it is just math. It assumes we can keep up a constant acceleration (from the traveller's viewpoint) for half the journey and the same constant deceleration for the other half. But can we? No, definitely not at our technology state, even if we assume we get the antimatter engine itself. As we get closer and closer to the speed of light, collisions with interstallar matter or even the light of the stars infront of us will become a significant problem. Relativistic aberration would mean that the closer we are to c, the bigger part of the universe will appear to be infront of us instead of behind us, so we'd get more light trying to slow us down (on the same principle that light we emit behind us accelerates us). Also light we receive from infront will be increasingly more blueshifted and energetic, increasing its slowdown effect. On the plus side, we can use this as a bonus for the deceleration phase of the journey, but facts are there is no free lunch - we'd have spent much more energy during acceleration.

And things slowing us down might be the least of our problems... rather, i think things might just be destrying us :P I.e. at some point even non-harmful light will appear to us like gamma rays and become deadly. And we won't be hitting just light on our way, but massive matter too - a single hydrogen atom might destroy the whole ship at a velocity high enough.





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