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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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RE: anti matter
By joset00 on 12/3/2006 9:27:33 PM , Rating: 2
@ AzureKevin:

True. But, there's a bigger catch, hidden in E=m*c^2.

Matter & Anti-matter produce high-energy photons, during anihilation; photons are massless particles, no matter how energetic they are.
The push-per-unit-time they'd produce would be insignificant, compared to nuclear devices or, even, to throwing stones, all other things being equal.
Analogy: Throw a 10Kg (or pounds) from a small boat, in mid-ocean & measure the reaction; do the same with small stones (same 10Kg/£)...


Cheers!


RE: anti matter
By Visual on 12/4/2006 5:00:29 AM , Rating: 2
wrong.
if you throw the small stones *fast enough*, you can get just as good a result.
light might be massless, but to counter that it's helluva fast ;)
it still has momentum. momentum preservation would indicate that if you manage to direct that light backwards, you'd gain momentum forwards.
in fact, light is the best possible "reaction mass" you could use, looking at the impulse per energy ratio, i.e. impulse per mass of fuel, specific impulse.


RE: anti matter
By joset00 on 12/4/2006 9:31:44 PM , Rating: 2
quote:
wrong.


Not necessarily.
You'd spend more energy than available throwing small stones "fast enough", in a closed system.
Moreover, matter/anti-matter anihilation (M/AMA) is, indeed the most eficient way of 'turning' mass into energy (E=m*c^2, where m=0, for the photon's rest mass); however, it would take a ship forever/all of the ship's mass to reach very close to c; what would be the point? Even a small mass portion left (say, you & your toothbrush), would refrain the whole system (ship) to reach such a speed.
(As for momentum, p=mv in Newtonian Mechanics, etc, just try to imagine the photons' impact, whenever one's X-rayed; acceleration would be tremendously faint/the 'ship' would be tremendously massive...).


Cheers!


RE: anti matter
By Visual on 12/6/2006 8:45:50 AM , Rating: 2
ok these boards arent the most convenient place for an argument, what with the lack of reply notifications and such... so this is gonna be my last post on the subject.

put simple, newtonian mechanics just doesn't apply here. p=mv, no longer. p=gamma*m0*v is still valid where m0>0, but gives 0/0 indefinite for photons. a more general formula, working for both massive and massless particles, is
p=sqrt(E^2-m0^2*c^4)/c
as you can see, for a set total energy E, the maximum momentum would be that of a massless particle, i.e. the photon. so light propulsion is the most efficient one possible. in other words, throwing a stone, or any other reaction mass, will always gain you less momentum than annihilating it and emmiting all of the energy behind you.

as to your speech about not being able to reach c - it is both corrent and unrelated to what is being discussed. we won't reach c, we can reach arbitrarily close to it though, and doing it with light propulsion is the most efficient way.


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