Saturday, November 28, 2009

Physics has Stopped Making Sense to Me

(H/T) to MR:
Crane first started thinking about artificial black holes 12 years ago when physicist Lee Smolin, now at Canada's Perimeter Institute for Theoretical Physics in Waterloo, Ontario, asked Crane to read the manuscript of his book The Life of the Cosmos.

Nobody knows what happens at the singularity of a black hole, the point where space and time become so warped that the laws of relativity break down. In his book, Smolin suggested that a new universe could be created and bud off. So universes in which black holes are likely to arise will give birth to more and more such universes. This means that our universe could be a baby universe, and is more likely to have come from one that is good at making black holes than one that isn't.

Crane then wondered what would happen if intelligent civilisations could make black holes. This would mean that life in these universes played a key role in the proliferation of baby universes. Smolin felt the idea was too outlandish and left it out of his book. But Crane has been thinking about it on and off for the last decade.

He believes we are seeing Darwinian selection operating on the largest possible scale: only universes that contain life can make black holes and then go on to give birth to other universes, while the lifeless universes are an evolutionary dead end.

His latest calculations made him realise how uncanny it was that there could be a black hole at just the right size for powering a starship. "Why is there such a sweet spot?" he asks. The only reason for an intelligent civilisation to make a black hole, he sees, is so it can travel the universe.

"If this hypothesis is right," he says, "we live in a universe that is optimised for building starships!"

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