Monday, January 24, 2011

Time to redefine 'universe?'

I can't read anything by physicist Steven Weinberg without learning something (albeit in a limited, popular-science kind of way). In a review of a 2010 book called "The Grand Design" by Stephen Hawking, Weinberg notes that there is a new and startling necessity for "fine tuning" of the universe to allow for life.

It has to do with dark energy, the energy of "empty" space that is driving the accelerating expansion of the universe. The problem is that, via quantum mechanical calculations, dark energy should be so powerful that the expansion would prevent galaxies, stars and planets from forming. Obviously, this is not the case, and other factors must cancel out almost all of that speed. The thing is, those other factors - not well enough understood to calculate - must be fine tuned to about 56 decimal places.

That's a lot of fine tuning! But if we live in a "multiverse" where a gazillion different universes exist, only a tiny fraction of which could support life, the fine tuning would be moot. A universe like ours could exist - would almost have to exist - along with all those other universes with entirely different laws of nature. And it is no big whoop that we happen to live in a good one.

The multiverse idea, much discussed among physicists these days, remains speculative, but multiple lines of scientific thought support it.

I've been interested in this stuff since I was about 10 and read George Gamow's book explaining general relativity. I wish I could rewind back to 10 years of age ... just to keep up on whatever unfolds next.

1 comment:

  1. A much more parsimonious model that allows for "fine tuning" is to be found in latest book "The Goldilocks Effect" which informally suggests a model which allows of "fine tuning" (for which there is much evidence in chemistry) while avoiding the extravagance of an infinity of multiple universes. The e-book version is available for free download from the “Unusual Perspectives” website.