Islands in the Multiverse

One of the biggest objections to the anthropic principle is that its subscribers seem to suffer from a lack of imagination. “A universe that differs from ours in even a small way is incompatible with existence itself. It is unimaginable.” or “The universe is so finely tuned to our existence, it must have been designed that way from the start. We may have even designed it that way ourselves, for ourselves. No other imaginable universe would be so well adapted to our existence.”

The counter arguments say, in response, that no other theory presented so far makes predictions that are either 1) testable at all or 2) correct. It is, in fact, an admitted embarrassment to physicists and cosmologists that the current standard model of physics gets the cosmological constant incorrect by about 120 orders of magnitude (the link is to an abstract, from which you can get the source in pdf format).

The long-known way around this conundrum is to posit multiuniverses. That is, there are not one, but many universes possible, each with a different set of physical parameters. We find ourselves in one that is compatible with our existence because we can exist in no other. The problem is that up to now every attempt to model difference universes with a different fundamental property (say, for instance, one with a different speed of light, or one with a different strength for gravity) leads quickly to a universe where we could not exist. It starts to look like you could twiddle with the fundamental properties until the cows come home and you still wouldn’t find a universe with cows, much less us.

Roni Harnik, however may have found a combination of parameters that works.

It all comes down to numbers. Harnik argues that there will be countless more universes with myriad properties different from our own. By varying just one property, cosmologists have been too conservative. Harnik, Kribs and Perez decided to highlight this flaw in anthropic reasoning by taking a radical measure: they switched off the weak nuclear force, one of the four fundamental forces in nature. In practice, this means changing a multitude of parameters and constants simultaneously.
By examining the equations that describe these processes, they made an astonishing discovery: the (different) universe is still capable of supporting observers.

Read the whole thing!

Explore posts in the same categories: Astronomy, post-modernism, Science

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