Why is the research on the foundations of QM necessary? … This post is meant to hold together some useful links touching on various aspects of this question.
He has interests in philosophy but has a PhD in astrophysics from Harvard. He maintains not just an isolated page on the measurement problem, but a whole compendium of them, which together touch on all issues related QM—and these form just a part of his Web site which also deals with many issues from philosophy proper like free-will, mind, knowledge, values, etc. Added attraction: He also keeps papers of historical relevance (like Schrodinger’s paper on quantum jumps, for instance).
His page on the measurement problem is very fascinating. He mentions all the relevant issues (including giving links to the topics), summarizes all the important positions in a very accurate manner (quoting passages from historically important papers). You are bound to get just the right kind of a perspective on this problem if you refer to this page and (what is easy to state): “all the references therein”!. Here is the page: [^] (which I had noted in my Twitter feed on 25 August 2019).
[This section added on 2019.09.18 07:43 IST]
See her blog post: “Good Problems in the Foundations of Physics” [^]. Go through the entirety of the first half of the post, and then make sure to check out the paragraph of the title “The Measurement Problem” from her list.
Not to be missed: Do check out the comment by Peter Shor, here [^], and Hossenfelder’s reply to it, here [^]. … If you are familiar with the outline of my new approach [^], then it would be very easy to see why I must have instantaneously found her answer to be so absolutely wonderful! … Being a reply to a comment, she must have written it much on the fly. Even then, she not only correctly points out the fact that the measurement process must be nonlinear in nature, she also mentions that you have to give a “bottom-up” model for the Instrument. …Wow! Simply, wow!!
Update (2019.09.18 07:43 IST): Also see a post she wrote a few months later: “The Problem with Quantum Measurements”, [^]. It generated 450 comments, but not many were too inspiring!
Here is one of the most lucid and essence-capturing accounts concerning this topic that I have ever run into [^]. Smolin wrote it in response to the Edge Question, 2013 edition. It wonderfully captures the very essence of the confusions which were created and / or faced by all the leading mainstream physicists of the past—the confusions which none of them could get rid of—with the list including even such Nobel-laureates as Bohr, Einstein, Heisenberg, Pauli, de Broglie, Schrodinger, Dirac, and others. [Yes, in case you read the names too rapidly: this list does include Einstein too!]
He explains at his blog how a lack of good answers on the foundational issues in QM leads to “the most embarrassing graph in modern physics” [^]. This post was further discussed in several other posts in the blogosphere. The survey paper which prompted Carroll’s post can be found at arXiv, here [^]. Check out the concept maps given in the paper, too. Phillip Ball’s coverage in the Nature News of this same paper can be found here [^].
See his pop-sci level paper “Quantum theory’s reality problem,” at arXiv [^]. He originally wrote it for Aeon in 2014, and then revised it in 2018 while posting at arXiv. Also notable is his c. 2000 paper: “Night thoughts of a quantum physicist,” Phil. Trans. R. Soc. Lond. A, vol. 358, 75–87. As to the fifth section (“Postscript”) of this second paper, I am fully confident that no one would have to wait either until the year 2999, or for any one of those imagined extraterrestrial colleagues to arrive on the scene. Further, I am also fully confident that no mechanical “colleagues” are ever going to be around.
[Added on 2019.05.05 15:41 IST]
OK. This all should make for an adequate response, at least for the time being, to those physicists (or physics professors) who tend to think that the foundational issues do not make for “real” physics, that it is a non-issue. … However, for obvious reasons, this post will also remain permanently under updates…
2019.04.15: First published
2019.04.16: Some editing/streamlining
2019.05.05: Added the paper by Prof. Kent.
2019.09.18: Added the section on Bob Doyle. Added a recent post by Sabine Hossenfelder.