Category Archives: Quantum Mechanics

Symmetry and Physics

Posted on August 6, 2022 by woit

It’s getting late, but I can’t help myself. Reading too many wrong things about symmetry and physics on Twitter has forced me to do this. And, John Baez says I don’t explain things. So, here’s what the relationship between symmetry … Continue reading →

Posted in Quantum Mechanics | 32 Comments

The Problem of Quantization

Posted on July 12, 2021 by woit

I’ve been watching Witten’s ongoing talks about geometric Langlands mentioned here, and wanted to recommend to everyone, mathematician or physicist, the first of them, on The Problem of Quantization (pdf here, video here, the question session is very worthwhile). For … Continue reading →

Posted in Quantum Mechanics, Quantum Theory: The Book, Uncategorized | 11 Comments

Fall Quantum Mechanics Class

Posted on September 7, 2020 by woit

I’ll be teaching a course on quantum mechanics this year here at Columbia, from a point of view aimed somewhat at mathematicians, emphasizing the role of Lie groups and their representations. For more details, the course webpage is here. The … Continue reading →

Posted in Quantum Mechanics | 19 Comments

(Imaginary) Time Asymmetry

Posted on August 6, 2020 by woit

When people write down a list of axioms for quantum mechanics, they typically neglect to include a crucial one: positivity (or more generally, boundedness below) of the energy. This is equivalent to saying that something very different happens when you … Continue reading →

Posted in Quantum Mechanics | 22 Comments

Metaphorical Worlds Interpretation

Posted on September 17, 2019 by woit

Chad Orzel has a piece at Forbes which I like a lot, where he argues that the “Many Worlds” of the MWI interpretation should be taken metaphorically, and thus the MWI really should be the “Metaphorical Worlds Interpretation”. I urge … Continue reading →

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An Apology

Posted on September 15, 2019 by woit

I’m afraid I made a serious mistake in this previous posting discussing Sean Carroll’s new book. Since the book was relatively reasonable, while the jacket and promotional material that came with it were nonsense, I assumed that Carroll was just … Continue reading →

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Regarding Papers about Fundamental Theories

Posted on September 9, 2019 by woit

Discussion in the comment section of the previous blog entry led me to do a little bit of historical research this morning, and I thought I’d write up the results here. First of all, for some interesting comments from people … Continue reading →

Posted in Favorite Old Posts, Quantum Mechanics | 26 Comments

Quantum Supremacy II

Posted on September 7, 2019 by woit

About the only thing that has transcended the bitter partisan divisions between Democrats and Republicans in the US during recent years has been quantum mechanics, with the enactment late last year of the National Quantum Initiative Act (the NQI was … Continue reading →

Posted in Quantum Mechanics | 26 Comments

Something Deeply Hidden

Posted on August 20, 2019 by woit

Sean Carroll’s new (available in stores early September) book, Something Deeply Hidden, is a quite good introduction to issues in the understanding of quantum mechanics, unfortunately wrapped in a book cover and promotional campaign of utter nonsense. Most people won’t … Continue reading →

Posted in Book Reviews, Multiverse Mania, Quantum Mechanics | 76 Comments

What’s the difference between Copenhagen and Everett?

Posted on August 18, 2019 by woit

I’ve just finished reading Sean Carroll’s forthcoming new book, will write something about it in the next few weeks. Reading the book and thinking about it did clarify various issues for me, and I thought it might be a good … Continue reading →

Posted in Quantum Mechanics | 27 Comments