Friday, April 27, 2007

Time, entropy and baby universes

CV talks about manufacturing universes that vanish as an evaporating black hole....
How Did the Universe Start? | Cosmic Variance

... The baby-universe idea at least has the chance to give rise to a spontaneous violation of time-reversal symmetry and explain the arrow of time. If we start with empty space an evolve it forward, baby universes can (hypothetically) be born; but the same is true if we run it backwards. The increase of entropy doesn’t arise from a fine-tuning at one end of the universe’s history, it’s a natural consequence of the ability of the universe to always increase its entropy. We’re a long way from completely understanding such a picture; ultimately we’ll have to be talking about a Hilbert space of wavefunctions that involve an infinite number of disconnected components of spacetime, which has always been a tricky problem. But the increase of entropy is a fact of life, right here in front of our noses, that is telling us something deep about the universe on the very largest scales.
Where entropy increases, there goes time. Or so it goes.

Update 4/28/07: Infinitely expanding universes birthing within infinitely expanding universes. Requirements for human observation to collapse probability waves. All interpretations of self-consistent mathematics, but way beyond bizarre. Which leads to the scary thought. Could he be right? Brrrr.

No comments: