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The Trouble with Quantum Mechanics (2017) [pdf]

38 pointsby alokraialmost 5 years ago

5 comments

l33tmanalmost 5 years ago
The trouble is physicists who work in foundational QM who still utters phrases like &quot;But the vista of all these parallel histories is deeply unsettling, and like many other physicists I would prefer a single history.&quot; and then they get dragged down into complicated alternative frameworks instead of the simple one they don&#x27;t like. Einstein wasn&#x27;t and will not be the only one to go down that path.<p>Over and over again it has been shown you need to calculate all the possible histories to arrive at the probability of a specific history to be realized. And if you need to calculate those histories to match the universe, chances are high the universe as well has to calculate them.
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chmaynardalmost 5 years ago
Source: The NY Review of Books<p>Posted on the website for UNM Physics 466, Fall 2017.<p>Course Text: &quot;Physical Mathematics, 2nd Ed.&quot; by Kevin Cahill<p>Kevin Cahill was born in New York, New York. He attended public and Catholic elementary schools, Regis High School, the University of Notre Dame, and Harvard University, receiving his PhD in physics in 1967 under the supervision of Roy Glauber (prix Nobel 2005). Cahill has done research at NBS, LBL, Ecole Polytechnique, Saclay, Orsay, and Harvard and has taught at Nice, Wesleyan, LSU, Indiana, Harvard, Fudan, and the University of New Mexico where he is a professor of physics and astronomy.
daltonlpalmost 5 years ago
Just gonna leave this here :)<p><a href="http:&#x2F;&#x2F;www.daltonlp.com&#x2F;de&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.daltonlp.com&#x2F;de&#x2F;</a>
jaygray0919almost 5 years ago
Am reading this article. But the act of reading is changing the rotation of the words. Probable cause: imperfection in my reading glasses.
Kednicmaalmost 5 years ago
I&#x27;m reminded of the Zen koan where the students cannot tell whether the flag is moving in the wind or the wind is moving around the flag. The master tells them that the mind, neither the flag nor the wind, is what is moving.<p>Both sides of the interpretative coin are needed. We must simultaneously understand that QM is epistemic and also that QM is contextual. The author asks,<p>&gt; How do probabilities get into QM?<p>Because knowledge of physical systems is always limited and QM is epistemic, all quantities we manipulate in QM are probabilistic. Further, the Kochen-Specker Theorem requires that some measurements be not fully determined by past history, as a matter of living in at least three dimensions of space. Finally, basic linear logic allows us to replicate most of QM&#x27;s effects with macrostates.<p>While Schrödinger hated this and used his famous cat thought-experiment to try to refute it, children learn about linear logic and probabilities in macrostates when they are given random toys or packs of trading cards, and today we recognize that it really is possible to condition relatively large differences in macrostate observations on single entangled or otherwise-prepared microstates.<p>&gt; In the [Everett] realist approach the history of the world is endlessly splitting;<p>Eh, kind of? But it&#x27;s also endlessly joining. We wouldn&#x27;t just be in a &quot;cosmic history&quot; which is &quot;sufficiently benign&quot; for us, but also we&#x27;re likely to be in a likely history. In fact, we&#x27;re <i>exactly</i> as likely to be on our current path as our current path is to be randomly picked from amongst the possible paths. So it turns out that Everett&#x27;s many-worlds analysis is a little tautological.<p>&gt; But how can something so nonlocal represent reality?<p>Finally, a good deep question. There are two parts to the answer, and each are deep enough to warrant a series of lectures. First, the Kochen-Specker Theorem, combined with general relativity, leads to the Free Will Theorem: When we measure particles, we are sending them a query, and they choose how to respond to the query from among the possible replies. Second, reality isn&#x27;t one single fabric, but interlocking systems of geometry and topology. With apologies to Wheeler, geometry tells reality how to interact, and topology tells reality how to propagate information. This insight leads to the co-hygiene principle [0].<p>The author sketches some possible directions for experimental work; it would be interesting to read about turning them into proper experiments and seeing the results.<p>[0] <a href="https:&#x2F;&#x2F;fexpr.blogspot.com&#x2F;2016&#x2F;06&#x2F;the-co-hygiene-principle.html" rel="nofollow">https:&#x2F;&#x2F;fexpr.blogspot.com&#x2F;2016&#x2F;06&#x2F;the-co-hygiene-principle....</a>
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