I want to talk about the multiple universe response to the Fine-Tuning Argument. For those of you who are unfamiliar with the fine-tuning argument here is a one-page handout that I give my students when we talk about it. It doesn’t contain all of the details of the argument, but it should give you the gist.

I’d like to talk about the Multiple Universe Hypothesis response. The basic idea behind this response is that we shouldn’t think  it is highly improbable to end up with a universe with life-permitting conditions if all of the universes with all of the different possible laws of nature and all of the different possible values for the strong nuclear force obtain.

It’s not as if one marble was drawn from the bag, and it happened to be our universe. All of the marbles (i.e. all of the possible universes) were dumped onto the table. They all were drawn. So the probability that a universe with life-permitting conditions was drawn is 1.

Normally, when I hear this response – I get told that we should think that the Multiple Universe Hypothesis is a live hypothesis because some interpretations of quantum mechanics allow for multiple universes.

Here’s the short explanation (sorry if I butcher it) as to how physicists come to take it seriously. Some interpretations of Quantum Mechanics will hold that for any possible position of an indeterminate sub-atomic particle, there is a universe where the particle ends up in that position. So if it’s indeterminate whether a particle will, in the next moment, be at position A, B, or C, then there is a (at least) one universe for each of those possibilities where the particle (or some counterpart particle) is in position A, B, and C – respectively.

Let’s grant that we should treat this Multiple Universe component of certain interpretations of Quantum Mechanics as a live option.

Here’s my question: Are there enough universes in this Quantum Mechanics model to respond to the fine-tuning argument? I don’t think there is. My understanding is that we need universes to account for all of the different possible arrangements of indeterminate quantum particles and that’s it. But those universes won’t be universes where the laws of nature are different from our world. At least, they won’t be universes where the values of the strong nuclear force are different.

Am I missing something here?

Granted there is a bunch to be said about the merits of the fine-tuning argument, but defending the Multiple Universe objection by quickly referencing interpretations of Quantum Mechanics seems bad to me.