Whether a physicist (in modern times and below a certain age) espouses MWI is quickly becoming a great litmus test for whether you should bother listening to them on anything that isn't established textbook material. Copenhagen is pseudo-scientific nonsense, and I'm amazed anyone can work on developing quantum computers while simultaneously denying the existence of what they're designing. I'd cut him some slack if this were just some tangential side point, but if it's critical to his argument the whole of it isn't worth anyone's time.

The reason people can get away with Copenhagen is that decoherence is absurdly effective in all realistic cases, causing there to very little uncertainty about whether and when a measurement happened. Insofar as we can all agree when a measurement happened, physicists operating under Copenhagen are going to be just as effective as those who understand MWI. And for most of the theoretical and especially computational aspects of quantum computers, this is the case. The only place where someone operating under the Copenhagen interpretation is going to falter is when they have to think hard and in novel ways about how to prevent decoherence.

So I really don't think interpretation is going to be correlated with advances in the computational aspects (i.e., what kind of problems are quantum computers good for once they are built, etc.) but I would predict that future insights in how to build computers which are robust against decoherence will be dominates by those who understand MWI.

"Insofar as we can all agree when a measurement happened, physicists operating under Copenhagen are going to be just as effective as those who understand MWI."

Agreed. If you're only worrying about the mundane medium-sized world we live in and what QM predicts we'll see in it, MWI vs. Copenhagen won't matter. Here, it does, as he's apparently using Cop. as a part of his argument.

"Whether a physicist (in modern times and below a certain age) espouses MWI is quickly becoming a great litmus test for whether you should bother listening to them on anything that isn't established textbook material."

Errr, do you mean you should bother listening or not bother?

My understanding of MWI doesn't go much beyond what I could understand of an early Wheeler paper (I thought it was from the mid-40s, but Wikipedia says MWI starts with the thesis of a student of his with the first publication in 1957 ... and I read that paper (whenever it was published) 25 years ago so it's gotten pretty fuzzy).

Hmmm, Wikipedia says MWI "along with the other decoherence interpretations and the Copenhagen interpretation" are the mainstream interpretations, so I suspect that answers my question.

  My understanding of MWI doesn't go much beyond what I could understand of an early Wheeler paper (I thought it was from the mid-40s, but Wikipedia says MWI starts with the thesis of a student of his with the first publication in 1957 ... and I read that paper (whenever it was published) 25 years ago so it's gotten pretty fuzzy).

Well, in this universe it started in '57. In yours, it seems, it is different. Where are you from traveller ?

On the other hand MWI super-advocate David Deutsch says: "An engaging, non-technical exploration of what the new theory of quantum information and computation tells us about life, the universe, and everything."

It's not so much that MWI is all that satisfying, it's that Copenhagen is incoherent.