If you are religiously convinced that the QIT interpretation is the only true one that doesn't make it true.
For me it is just one of the many interpretations and I think that it is wrong on par with all the others that I'm aware of.
If this wasn't the case then the measurement problem and the unification with the relativity theory (or with a theory that supersedes the relativity) would be already solved today.
I'm really not in the field, but I don't think that anyone that actively works on QM is debating on solved problems.
I am absolutely not religiously convinced that QIT is the only true explanation. In fact, I explicitly say at the end of my talk that it is not, that multiple-worlds is equally valid, and which you choose is a matter of personal preference. But if want to argue that no solution exists (and this is Weinberg's claim) then you have to consider all of the solutions on the table, and Weinberg does not. He deliberately ignores the fundamental (and IMHO ultimately clarifying) fact that entanglement and measurement are intimately related (and are in fact the same physical phenomenon). It is entirely unsurprising that anyone who ignores this fact ends up believing that there is a big mystery. But in fact there is no big mystery. There are only people who are mystified because they are ignoring (or ignorant of) this crucial fact.
> There are only people who are mystified because they are ignoring (or ignorant of) this crucial fact.
I don't think that's the only reason people are mystified. From what Weinberg says, and I've heard from other physicists, when you get to the root of the issue they just won't accept a multiverse theory.
It has profound philosophical consequences, so I guess they go looking for ways to make their understanding of QM fit their strongly held preconceptions. Some avoid this fact you just mentioned, but others fight the Born rule derivations or wrongly apply Occam's Razor or have more original objections.
These things are not unrelated :) If you accept that there is only the wave function as in the bare formalism, either an infinity of worlds or zero worlds, like in QIT, are the logical outcomes.
But I am not saying they "have to" - I'm saying that is their reason for not accepting the bare formalism.
> These things are not unrelated :) If you accept that there is only the wave function as in the bare formalism, either an infinity of worlds or zero worlds, like in QIT, are the logical outcomes.
Yep.
> But I am not saying they "have to" - I'm saying that is their reason for not accepting the bare formalism.
Well, OK, but then the burden is on them to come up with something better. QM is one of the most thoroughly tested scientific theories of all time. If you want to call yourself a scientist you can't legitimately reject it just because it doesn't make you feel warm and fuzzy inside.
Maybe I agree with you, but science is built on philosophy, which is not rigorous - but based on fuzzy feelings of what is right.
The fact that we accept QM because it predicts the outcome of experiments is philosophy. So I could theoretically imagine someone holding the belief in our universe being what it seems higher than mathematical sense.
Yet my primary point is physicists are just human and have all the same irrational tendencies as the rest of us. You can't ignore their feelings if you hope to convince them of something.
In your everyday experience, you are constantly bombarded with overwhelming evidence that space and time are two completely different things, that matter and energy are two completely different things, that life is much too complex and well adapted to its environment to have arisen without an intelligent designer, and that the sun revolves around the earth. And yet, none of these things are true.
Likewise, you are constantly bombarded with overwhelming evidence that you are a classical physical entity living in a classical universe. But that is not true either. It's a very good approximation to the truth, good enough for most day-to-day purposes, but it is not the truth.
You can choose to accept these facts, or you can choose to bury your head in the sand. But you cannot legitimately say that there is a "problem with quantum mechanics" when in fact what is going on is that you have chosen to bury your head in the sand. There is no more a "problem" with quantum mechanics than there is a "problem" with relativity, evolution, or the Copernican theory. There is no intractable mystery here, only people who choose not to accept what the math is telling them.
I don't think that's been solved either or most physicists for that matter. I've read some of the attempts and they are not terrible good.
I don't think Ron Garret even touched on the Born rule, Everett of many worlds just hand waves and assumes it. The attempts I've seen are basically of the form that if the rule was different from the probability equaling the absolute amplitude squared then reality wouldn't come out as we find, so it must be so, which is not much of an explanation in my book.
It's true that I don't talk about the Born rule or multiple worlds in the paper, but I do talk about multiple worlds in the video (at the end, during the Q&A) and in the blog posts I linked to above.
As for the Born rule, what kind of an explanation are you hoping for? Some things can't be explained beyond, "That's just how it is." For example, why do the fundamental physical constants have the values that they have?
Two of the appealing arguments for many worlds type interpretations are that the number of required assumptions is small, and that it gives a reasonable physical intuition for why measurement outcomes occur as they do. Having to bolt on the Born rule weakens both of these.
In fact, I would even go so far as to say that if you are going to merely "enforce" the Born rule without justification, then you are no longer proposing an Everettian interpretation. The whole point of these interpretations is that simply "unitary quantum mechanics" describes the whole universe.
I agree that bolting on the Born rule seems a weakness of the many world view. It would be nice if you could say everything follows the Schrodinger equation and hence the probabilities naturally come out the way they do but it doesn't seem to work that way very easily.
Everett himself however seems to basically "enforce" the Born rule without justification so I guess that would be Everettian.
Probability is a funny thing to deal with. Say you have an experiment where you push a button and a red light or green comes on based on some quantum effect but the green light is 1000x more likely. In many worlds you'd end up with different worlds with an observer seeing one or another but it's tricky to see how the 1000x thing comes in.
