Category Archives: Quantum Mechanics

Not So Spooky Action at a Distance

Posted on June 11, 2019 by woit

I’ve recently read another new popular book about quantum mechanics, Quantum Strangeness by George Greenstein. Before getting to saying something about the book, I need to get something off my chest: what’s all this nonsense about Bell’s theorem and supposed … Continue reading →

Posted in Book Reviews, Quantum Mechanics | 62 Comments

Is Quantum Mechanics a Probabilistic Theory?

Posted on September 7, 2018 by woit

There is a simple question about quantum theory that has been increasingly bothering me. I keep hoping that my reading about interpretational issues will turn up a discussion of this point, but that hasn’t happened. I’m hoping someone expert in … Continue reading →

Posted in Quantum Mechanics | 74 Comments

What is Real?

Posted on March 22, 2018 by woit

There’s a new popular book out this week about the interpretation of quantum mechanics, Adam Becker’s What is Real?: The Unfinished Quest for the Meaning of Quantum Physics. Ever since my high school days, the topic of quantum mechanics and … Continue reading →

Posted in Book Reviews, Quantum Mechanics | 74 Comments

Various Topics in Interpretation of Quantum Mechanics

Posted on October 11, 2017 by woit

A couple of recent discussions about quantum mechanics that may be of interest: There’s a recent paper out by Don Weingarten that looks looks like it might have a different take on the fundamental “many-worlds” problem of, as he writes: … Continue reading →

Posted in Quantum Mechanics | 19 Comments

The Free Particle

Posted on September 29, 2015 by woit

Following on my notes about Euler’s formula, I’ve finally finished some work on another piece of elementary exposition, a discussion of the free quantum particle, which can be found as chapters 10, 11 and 12 of the book I’m working … Continue reading →

Posted in Quantum Mechanics | 19 Comments

This Week’s Hype

Posted on November 3, 2014 by woit

From commenter Hendrik, there’s the news that USC has put out a press release claiming that String Theory Could Be the Foundation of Quantum Mechanics. These claims are based on this paper, which argues that finding the Heisenberg commutation relations … Continue reading →

Posted in Quantum Mechanics, This Week's Hype | 5 Comments

Use the Moment Map, not Noether’s Theorem

Posted on August 28, 2014 by woit

For a fourth provocative slogan about quantum mechanics I’ve chosen: Use the moment map, not Noether’s Theorem. Pretty much every physics textbook these days explains the way symmetry principles work as: Start with an action functional, invariant under a Lie … Continue reading →

Posted in Favorite Old Posts, Quantum Mechanics | 25 Comments

Nature is Fundamentally Conformally Invariant

Posted on August 20, 2014 by woit

For a third slogan I’ve chosen: Nature is fundamentally conformally invariant. Note the weasel-word “fundamentally”. We know that nature is not conformally invariant, but the kind of thing I have in mind is pure QCD, where the underlying classical theory … Continue reading →

Posted in Favorite Old Posts, Quantum Mechanics | 33 Comments

Grand Unification of Mathematics and Physics

Posted on August 20, 2014 by woit

For a second slogan about quantum mechanics I’ve chosen: Quantum mechanics is evidence of a grand unification of mathematics and physics. I’m not sure whether this slogan is likely to annoy physicists or mathematicians more, but in any case Edward … Continue reading →

Posted in Favorite Old Posts, Quantum Mechanics, Uncategorized | 7 Comments

Quantum Theory is Representation Theory

Posted on August 16, 2014 by woit

For a first slogan (see here for slogan zero) I’ve chosen: Quantum theory is representation theory. One aspect of what I’m referring to is explained in detail in chapter 14 of these notes. Whenever you have a classical phase space … Continue reading →

Posted in Favorite Old Posts, Quantum Mechanics | 43 Comments