On Fine-Tuning and the Multiverse

The Fine-Tuning Problem

I've been thinking a lot lately about the problem of fine-tuning and how it may or may not be resolved by appeal to a multiverse. This has been prompted by recent correspondence with the philosopher Philip Goff and by the book I am currently reading, The Beginning of Infinity by David Deutsch. I hope to get around to discussing Deutsch's ideas in future, but for now I'm focusing on an argument put forth by Roger White and endorsed by Goff.

The fine-tuning problem is just that the laws of physics describing the universe seem to be fine-tuned so as to allow life to exist. While trying not to be too parochial in our assumptions about what life requires to exist, at least in a universe even vaguely like ours, it seems reasonable to assume that it must at least have time and a stable environment in which to evolve, access to sources of energy and a varied assortment of building blocks from which to assemble itself.

But if the physical constants were slightly different, then perhaps stars, heavier elements or atoms could not have formed. Perhaps the universe would never have expanded from its initial hot, dense state, or would have recollapsed too quickly, or perhaps it would have expanded too quickly for particles to come together at all. When we say the universe appears to be fine-tuned, we are claiming that it appears to be delicately balanced so as to allow complex evolving self-replicators (i.e. life) to exist -- that almost any tweak we imagine to the constants or the laws of physics would result in a simpler, lifeless universe. This curious observation seems to demand an explanation.

The anthropic principle goes wild

The anthropic principle has been much discussed and it is likely that you have already come across it. It's a strange and counter-intuitive idea because it seems to place human beings in a privileged central place in our account of why our world is the way it is.

I want to raise the subject because the anthropic principle is exactly the kind of logical or philosophical argument that might have a bearing on the fundamental existential questions I mentioned in my last post.

The anthropic principle is a simple but profound idea that at first sounds like a useless tautology. It explains that we shouldn't be too surprised to find ourselves in an environment that is so well suited to us, because if our environment were not as it is then we would not be as we are.

To paraphrase Douglas Adams: to marvel at the many wonderful and hospitable aspects of our world that enable our existence is like a sentient puddle being impressed with how well its pothole fits its shape.

The anthropic principle explains why the earth is positioned in the narrow band of space at just the right distance from the sun to allow liquid water to exist. It explains how life can have come into existence despite the long odds of its arising by chance. It explains how this life can have evolved into intelligent self-reflective creatures such as ourselves.