I’ve spent the last few months exploring an unorthodox explanation of cosmological fine-tuning, which I discuss in this article and this talk. Part of my motivation was dissatisfaction with the two more conventional alternatives: God and the multiverse hypothesis. And part of the my dissatisfaction with the multiverse hypothesis was rooted in Roger White’s intriguing article arguing that the multiverse hypothesis doesn’t even explain the fine-tuning. As I said in a couple of recent talks on fine-tuning, it wasn’t that I was happy with the theory I’d come up with; to paraphrase Churchill, the view I was considering seemed to me to be the worst explanation of fine-tuning apart from all the others.
However, I think I’ve just changed my mind on the White article. White’s essential point is that what we want explained is why this universe is fine-tuned, whilst the postulation of a multiverse only explains why a universe is fine-tuned (I’m sure many will right now be screaming “But what about the Anthropic Principle/selection effect????”…see my discussion in the talk from 17:50-24:50.). However, at a recent talk I gave on this topic at Rutgers University, a discussion with Eddie Chen made me appreciate that this distinction collapses if the laws of nature are not contingent, that is to say, if our universe had to have the laws it has (and I’m independently attracted to philosophical views in which this is the case). If our universe had to have the laws of nature it in fact has, then it had to be fine-tuned, so long as it exists. This doesn’t mean that the fine-tuning puzzle goes away; it just turns into a different question. The question is not “Why is our universe fine-tuned?” but “Why does our fine-tuned universe exist rather any of the many very similar universes that aren’t fine-tuned?” Crucially, the multiverse theory can explain this: If there is a high enough number of universes, then there is likely to be one which, like ours, is fine-tuned.
So I’m now back to thinking probably some form of the multiverse hypothesis, perhaps the quantum mechanical version, is the best explanation of the fine-tuning. But I don’t regret exploring my “middle way” hypothesis. It’s philosophically important to explore new theories and explanations, and to try things out. After all, philosophers are supposed to question everything. It’s a shame that our intellectual climate makes this difficult. We pride ourselves on being liberal and free thinking, but it was hard to talk about this stuff. I could feel myself been categorised as “religious” or “new age” just for trying out a view.
Of course, we shouldn’t get lost in flights of fancy, but we should examine the arguments without prejudice. This was the enlightenment aim, but somewhere along the way that aim was replaced by dogmatic adherence to an ideological view of what science is “supposed to look like”. I look forward to the day when the enlightenment ideal of rigorous objectivity overcomes, once and for all, such ideologies.