{Golgafrincham’s} people decided it was time to rid themselves of an entire useless third of their population, and so the descendants of the Circling Poets concocted a story that their planet would shortly be destroyed in a great catastrophe. (It was apparently under threat from a “mutant star goat”). The useless third of the population (consisting of hairdressers, tired TV producers*, insurance salesmen, personnel officers, security guards, management consultants, telephone sanitizers and the like) were packed into the B-Ark, one of three giant Ark spaceships, and told that everyone else would follow shortly in the other two. The other two thirds of the population, of course, did not follow and “led full, rich and happy lives until they were all suddenly wiped out by a virulent disease contracted from a dirty telephone”.

http://en.wikipedia.org/wiki/Milliways#Golgafrincham

BTW: There is no evidence in all the antimatter we’ve actually produced that it ‘repels’ light. And when you mix matter and anti-matter, there is no way to direct the thrust of gamma rays…..

Personally, I think the odds are higher that humanity will survive whatever it does to itself than either the chances of developing faster-than-light travel cheaply enough to transport a significant number of people off-planet, or the chances of adapting to the new ecosystem. At least in the next few centuries.