Insights Interview with Astrophysicist: Adam Becker - Comments

[vanhees71]

Well if you want a causal account of the experiment shown in the Sci Am article, then either the electron hitting the screen causes the agent to insert or not insert the lens (forward causality) or the agent’s decision to insert or not insert the lens causes the electron to hit the screen in the correct place (retrocausality). One might deny that the Sci Am experimental prediction will be seen because a human is making the decision (unlike the Kim et al experiment where beam splitters “make the decision”). QM doesn’t make different predictions based on conscious versus nonconscious intervention so if you believe that, you would be claiming QM (and QFT by extension) is wrong. Hardy proposed an experiment to explore this possibility https://arxiv.org/pdf/1705.04620.pdf

Of course, I don't claim that. My point simply was that all hitherto done experiments with entangled photons and other systems to test Bell's inequality against the prediction of its violation by QT are all fully understood within relativistic local microcausal QFT and thus by construction exclude both spooky-action at a distance and the possibility of retrocausality. All there is is the state preparation in the very beginning which implies the correlations described by entanglement, and all experiments agree with the predictions of QT (particularly relativistic QFT). I don't expect any changes with this conclusion when using humans for the switching decision, but of course one has to do the experiment to be really sure. Physics is indeed an empirical scienc!

 

[vanhees71]

It is erroneous because it is self-contradictory. vanhees71 uses a cut, yet he says there is no cut.

Also, he claims to have a solution to the measurement problem that involves neither hidden variables nor MWI, only coarse graining. This is basically a variant of "decoherence solves the measurement problem", which is an error.

And yes, it is an argument from authority - but there is a reason that the standard texts like Landau and Lifshitz or Weinberg use a Copenhagen-like interpretation.

I don't use a cut. I use real-world macroscopic equipment to prepare states and perform measurement (well, I let my experimental colleagues do that, because I'd for sure mess up the experiment being a theorist ;-)).

I don't claim to solve any "measurement problem". I deny that one exists do begin with for the simple reason that we are able use QT to successfully predict the outcome of measurements (in terms of probability and statistics).

Landau and Lifshitz use indeed a Copenhagen-like flavor, but they hardly discuss interpretational issues at all. Weinberg doesn't take any side but says that the interpretational problem is undecided, although I also fail to see where this apparent problem might be for the reason just given. Weinberg's chapter on interpretation is, however, among the best I've read about the issue (which is as valid for the entire content of this and all his other textbooks). Nevertheless I'm not sharing his opinion on the final dictum on interpretation.

 

[atyy]

I don't use a cut. I use real-world macroscopic equipment to prepare states and perform measurement (well, I let my experimental colleagues do that, because I'd for sure mess up the experiment being a theorist ;-)).

That is a cut, because the "macroscopic" equipment is not included in the quantum state.

I don't claim to solve any "measurement problem". I deny that one exists do begin with for the simple reason that we are able use QT to successfully predict the outcome of measurements (in terms of probability and statistics).

That alone would be ok (not my position, but certainly one that is coherent and attractive), but you often add that the macroscopic equipment can be included in the quantum state by suitable coarse graining (without hidden variables or MWI) - that would not be ok.

 

[RUTA]

Silberstein and I gave a talk at Univ of Maryland on Wed. Afterwards, we had dinner with Jeff Bub and he had some interesting responses to Adam’s book. He was not happy that the book made it seem like he wasn’t aware of Bohm’s interpretation when he was Bohm’s grad student. In fact, Bohm wasn’t taking any more students when Jeff was picking an advisor, but Bohm took Jeff precisely because Jeff had done an undergrad thesis on Bohm’s interpretation. More stories from Bub to follow :-)

 

[atyy]

So did Jeff Bub buy Adam's book?

 

[RUTA]

So did Jeff Bub buy Adam's book?

He was interviewed for the book, so of course he received a complimentary copy :-)

 

[martinbn]

That is a cut, because the "macroscopic" equipment is not included in the quantum state.

Why is this a cut? If you study a particular system you can ignore the rest of the universe or use an approximate description of some other systems if that is good enough. It would be a cut only if you say that all of the rest cannot be in principle described by quantum mechanics and you need at some point a classical system.

 

[RUTA]

Here's another Bub story from our dinner on Wed related to the book. Adam is bemoaning the fact that so many physicists don't bother to articulate their ontological assumptions concerning QM, indeed some even deny having them altogether! After arguing against this attitude, Adam says physics students should at least be shown various interpretative options for QM.

At dinner, I told Jeff I hadn't seen any real progress in the debate over QM interpretations since I began work in the field in 1994. We get new experiments, some of which are even motivated by a particular interpretation, but then everyone brings out their favorite interpretation and explains the experimental result to their own satisfaction. The people I first met in foundations of physics (FoP) in 1994 are still today arguing for what are basically their same interpretations from 1994. Jeff said he sees FoP splitting along two lines -- the old line of hackneyed interpretative debate and a new line exploring the deeper mathematical underpinnings of quantum theory, e.g., as with quantum information theory. He thinks the future of FoP lies in this new line.

 

[PeterDonis]

We get new experiments, some of which are even motivated by a particular interpretation, but then everyone brings out their favorite interpretation and explains the experimental result to their own satisfaction.

That's because all interpretations make the same predictions for all experimental results; they have to, since they all use the same (or equivalent) mathematical machinery.

To make progress, someone needs to come up with a new theory--different mathematical machinery that makes the same predictions for experiments that have already been done, but makes different ones for some experiment that hasn't yet been done. If the new theory also rules out some subset of interpretations of current QM, then running the new experiment might help, if it confirms the new theory (and therefore contradicts current QM).

 

[RUTA]

That's because all interpretations make the same predictions for all experimental results; they have to, since they all use the same (or equivalent) mathematical machinery.

To make progress, someone needs to come up with a new theory--different mathematical machinery that makes the same predictions for experiments that have already been done, but makes different ones for some experiment that hasn't yet been done. If the new theory also rules out some subset of interpretations of current QM, then running the new experiment might help, if it confirms the new theory (and therefore contradicts current QM).

As a physicist involved in this program, I agree completely. I started working on an interpretation of QM so I could have an ontology for all of physics. In other words, I want an ontology that is just as good for GR as it is for QM. I knew that such an ontology would change the way we view reality and consequently lead to new physics, e.g., when we changed from geocentricism to heliocentricism. And that's what excited me about FoP. But, I found many participants didn't even care if their interpretation was compatible with physics other than QM. I can't tell you how many talks I've given with Silberstein (philosopher of physics) where he told me we had to restrict our talk to applications in QM because that's all the audience was interested in. Given that restriction, I fail to see the advantage of any interpretation over any other. Indeed, my adynamical interpretation of QM is unnecessarily deviant from intuition if all it's good for is interpreting QM. The reason I'm so pleased with it is precisely because I can use it to understand all of physics, even resolving controversies in classical physics, e.g., paradoxes of CTCs, dark matter, dark energy, horizon problem, etc. Sorry to prattle on, this is a pet peeve of mine :-)

 

[ZeGato]

This was interesting and thought-provoking, I hope that the effects last until longer when it'll be clearer for me to think about it.

 

[kith]

I started working on an interpretation of QM so I could have an ontology for all of physics. In other words, I want an ontology that is just as good for GR as it is for QM. I knew that such an ontology would change the way we view reality and consequently lead to new physics

Should we expect that the new ontology can be guessed from within the old theories? Hardy argues a bit against this in noting that it was impossibly to discover spacetime curvature as the solution to the conceptual problems of Newtonian gravity (instantaneous action at a distance). Contemporary ontologies for how the action could be transmitted didn't point in the correct direction at all. I recently started a thread on his approach.

 

[RUTA]

Should we expect that the new ontology can be guessed from within the old theories? Hardy argues a bit against this in noting that it was impossibly to discover spacetime curvature as the solution to the conceptual problems of Newtonian gravity (instantaneous action at a distance). Contemporary ontologies for how the action could be transmitted didn't point in the correct direction at all. I recently started a thread on his approach.

The ontology I have for GR and QM (see our book "Beyond the Dynamical Universe") was obtained by resolving mysteries in those theories. So, as you suggest, it doesn't lead to new theories of physics, only new physics within existing theories.