Wednesday, April 27, 2016

Lost in the Multiverse

Physicist Adam Frank is impressed, as most scientists are, with the degree of fine-tuning scientists are finding in the cosmos. He writes:
As cosmologists poked around Big Bang theory on ever-finer levels of detail, it soon became clear that getting this universe, the one we happily inhabit, seemed to be more and more unlikely. In his article, Scharf gives us the famous example of carbon-12 and its special resonances. If this minor detail of nuclear physics were just a wee bit different, our existence would never be possible. It’s as if the structure of the carbon atom was fine-tuned to allow life.
But this issue of fine-tuning goes way beyond carbon nuclei. It's ubiquitous in cosmology.
Change almost anything associated with the fundamental laws of physics by one part in a zillion and you end up with a sterile universe where life could never have formed. Not only that, but make tiny changes in even the initial conditions of the Big Bang and you end up with a sterile universe. Cosmologically speaking, it’s like we won every lottery ever held. From that vantage point we are special — crazy special.
Indeed, the figure of one part in a zillion hardly begins to capture the incomprehensible precision with which these cosmic constants and forces are set, but lest one conclude that perhaps it's all purposefully engineered, Frank quickly waves the reader away from that unthinkable heresy:
Fine-tuning sticks in the craw of most physicists, and rightfully so. It’s that old Copernican principle again. What set the laws and the initial conditions for the universe to be “just so,” just so we could be here? It smells too much like intelligent design. The whole point of science has been to find natural, rational reasons for why the world looks like it does. “Because a miracle happened,” just doesn’t cut it.
This is a bit too flippant. Intelligent design doesn't say "a miracle happened" as though that were all that's needed to account for our world. ID says simply that natural processes are inadequate by themselves to explain what scientists are finding in their equations. Even so, it's ironic that every naturalistic theory of cosmogensis does say that the origin of the universe was miraculous if we define a miracle as an extraordinarily improbable event that does not conform to the known laws of physics.

In any case, how do scientists who wish to avoid the idea of purposeful design manage to do so? Well, they conjure a near infinite number of universes, the multiverse, of which ours is just one:
In response to the dilemma of fine-tuning, some cosmologists turned to the multiverse. Various theories cosmologists and physicists were already pursuing — ideas like inflation and string theory — seemed to point to multiple universes.
Actually, these theories allowed for the existence of other universes, they don't require them, but be that as it may, the advantage of positing a multiplicity of different worlds is that the more different worlds you have the more likely even a very improbable world will become, just as the more times you deal a deck of cards the more likely it will be that you'll deal a royal flush. Frank, though, issues a caveat:
There is, however, a small problem. Well, maybe it’s not a small problem, because the problem is really a very big bet these cosmologists are taking. The multiverse is a wildly extreme extrapolation of what constitutes reality. Adding an almost infinite number of possible universes to your theory of reality is no small move.

Even more important, as of yet there is not one single, itty-bitty smackeral of evidence that even one other universe exists (emphasis mine)....

Finding evidence of a multiverse would, of course, represent one of the greatest triumphs of science in history. It is a very cool idea and is worth pursuing. In the meantime, however, we need to be mindful of the metaphysics it brings with it. For that reason, the heavy investment in the multiverse may be over-enthusiastic.

The multiverse meme seems to be everywhere these days, and one question to ask is how long can the idea be supported without data (emphasis mine). Recall that relativity was confirmed after just a few years. The first evidence for the expanding universe, as predicted by general relativity, also came just a few years after theorists proposed it. String theory [upon which the multiverse idea is based], in contrast, has been around for 30 years now, and has no physical evidence to support it.
I'm surprised Frank doesn't mention the irony in this. Scientists feel impelled to shun ID because, they aver, it's not scientific to posit intelligences for which there's no physical evidence (set aside the fact that the existence of a finely-tuned universe is itself pretty compelling evidence). Yet, in its stead they embrace a theory, the multiverse, for which, as Frank readily admits, there's no physical evidence and yet they think this is somehow more reasonable than embracing ID.

When you're determined to escape the conclusion that the universe is intentionally engineered, you'll embrace any logic and any theory, no matter how bizarre, that allows you to maintain the pretense of having refuted the offending view.

Pretty amusing.