phayes

Koberlein's explanation is okay but I read Burns's "Keep velocity constant on z-axis" as an instruction rather than an assumption. In that light the error doesn't appear so subtle (it manifests as a simple error of "conservation arithmetic").

"Oversimplified" is one way of putting it. I'd prefer to call it "simply incorrect". The manner in which the ring's rest mass is increased [decreased] is ignored[1]. If you don't ignore it, and apply conservation of (relativistic) angular momentum to the box-ring system, you'll see there's no reason to expect a net thrust at all.

[1] https://iopscience.iop.org/article/10.1088/1742-6596/1141/1/...

Well, I'd strongly disagree with Hossenfelder's contention that "what this math is about has remained unclear" (see e.g. the links in here https://news.ycombinator.com/item?id=19315457 ) but then there is this:

> A phenomenologist myself, I am agnostic about different interpretations of what is indeed the same math, such as QBism vs Copenhagen or the Many Worlds. But I agree with the philosopher Tim Maudlin that the measurement problem in quantum mechanics is a real problem – a problem of inconsistency – and requires a solution.

It's inconsistent to claim to be be agnostic about interpretation and at the same time believe that the (big) measurement problem is a real problem. Whether it's a real problem or not is interpretation-dependent. See e.g. https://www.mdpi.com/1099-4300/17/11/7374/htm

> for all this experiment to be valid to begin with,the idea that superpositions exist must be true, correct?

Depends what you mean by "exist". All that needs to be true - and is true - is that QM provides an accurate model of the experiment. For many of us, QM is just probabilistic mechanics; i.e. probability theory applied to mechanics[1], and so long as you maintain the distinction between (epistemic) probability space states and (ontic) configuration space states (something the article under discussion here unfortunately fails to do), no ontic existence of [superposition] states is ever assumed in the first place.

[1] More precisely, a natural and necessary generalisation of the classical, Kolmogorovian probability theory you might be familiar with (necessary because of the noncommuting random variables):

https://news.ycombinator.com/item?id=19315457

See also: http://blogs.discovermagazine.com/cosmicvariance/files/2011/...

No, it mustn't! The logical negation of the conjunction "classical* and local" is "non-classical or non-local". Electrical universe theory"?! Please stick to standard and generally accepted quantum foundations / interpretation. There's no (non-local) spookiness to be taken out of QM in the first place - except for those who choose to reject the non-classical option. %

* Your last remarks suggest you haven't read those Werner refs and don't know what is meant by the term "classical" as I've used it here - it's a reference to the structure of (general) probability state spaces, not to classical physics per se - and you should substitute "(naively) realist" for "classical" in the above.

% And those familiar with the probability theoretic aspects (see my links in a comment in a different thread here, or Tom Banks's teaser: http://blogs.discovermagazine.com/cosmicvariance/files/2011/... ), probably won't want to do that. For example, the reason violations of Bell-type inequalities occur in QM is mundane from this perspective: "What on earth did you expect?! You have observables that don't commute! Use the appropriate inequality." https://sci-hub.tw/10.1016/0375-9601(87)90075-2

Well, that is what I said: non-locality is just an artifact "of certain interpretations / modifications of QM". Bell's theorem doesn't prove non-locality; what it proves is that no (alternative) theory (of mechanics) that's both classical, aka naively realist, and local could reproduce QM's successful predictions (of those experimental results).

> If foundations of QM are non-local

They're not. Non-locality is an artifact of certain interpretations / modifications of QM (where it isn't simply a misconception). See e.g. https://sci-hub.tw/10.1088/1751-8113/47/42/424011 and https://arxiv.org/abs/1411.2120 or the QBism intro https://arxiv.org/abs/1311.5253 or Ray Streater's old EPR webpage https://web.archive.org/web/20151117174141/http://www.mth.kc... or Gell-Mann's video: https://www.youtube.com/watch?v=gNAw-xXCcM8 or...

"Both monism and many worlds can be avoided, but only when one either changes the formalism of quantum mechanics—typically in ways that are in conflict with Einstein’s theory of special relativity—or if one understands quantum mechanics not as a theory about nature but as a theory about knowledge: a humanities concept rather than science."

Tut-tut. There's nothing "humanities rather than science" about the understanding that QM is 'just' probability theory

https://arxiv.org/abs/quant-ph/0601158 https://terrytao.wordpress.com/tag/noncommutative-probabilit... https://arxiv.org/abs/math-ph/0002049 https://ncatlab.org/nlab/show/quantum+probability

applied to mechanics (and interpreted sensibly, as it is in any 'neo-Copenhagen' or 'pragmatist' interpretation). Grandiose and/or bizarre 'psiontology' is easily avoided.

"Objective wavefunction collapse" is not a good "aka" for the CI. There is a great deal of objectivity in it but there's an essential element of subjectivity (shared by neo-CI descendants of the CI such as QBism and Rovelli's relational interpretation) too. Streater's discussion of EPR explains why: https://web.archive.org/web/20151117174141/http://www.mth.kc...

Broadly speaking, the CI and its "radical" psi-epistemic* relatives interpret QM as (generalised) probability theory applied to mechanics: https://telescoper.wordpress.com/2017/06/23/the-quantum-mech... It's hardly a cop-out. See e.g. Rovelli's take on what the ontological ramifications are: https://arxiv.org/abs/1712.02894

* https://www.sciencedirect.com/science/article/pii/S135521981...