### About

### Quantum Theory, Groups and Representations

### Not Even Wrong: The Book

### Subscribe to Blog via Email

### Recent Comments

- Visit to Brown 3

Douglas Natelson, Peter Woit, Alessandro Strumia - Euclidean Twistor Unification, version 2.0 27

Peter Woit, Anonymous s, Peter Woit, Kingsuk Maitra, Lowell Brown, Peter Woit [...] - Conversations on Quantum Gravity 42

Peter Woit, Juan Cristobal Latorre, Peter Woit, Suomynona, anon2, Peter Woit [...] - This Week's Hype 17

Peter Woit, Matthew Foster, Peter Woit, Ian McCormack, Peter Woit, Peter Woit [...] - Some Math Items 8

nad, kitchin, nad, SD, David Roberts, David Roberts [...]

- Visit to Brown 3
### Categories

- Book Reviews (116)
- BRST (13)
- Euclidean Twistor Unification (4)
- Experimental HEP News (152)
- Fake Physics (6)
- Favorite Old Posts (50)
- Film Reviews (15)
- Langlands (40)
- Multiverse Mania (154)
- Not Even Wrong: The Book (27)
- Obituaries (32)
- Quantum Mechanics (20)
- Quantum Theory: The Book (7)
- Strings 2XXX (21)
- Swampland (18)
- This Week's Hype (120)
- Uncategorized (1,226)

### Archives

### Links

### Mathematics Weblogs

- Alex Youcis
- Alexandre Borovik
- Anton Hilado
- Cathy O'Neil
- Daniel Litt
- Danny Calegari
- David Hansen
- David Mumford
- David Roberts
- Emmanuel Kowalski
- Harald Helfgott
- Jesse Johnson
- Johan deJong
- Lieven Le Bruyn
- Mathematics Without Apologies
- Michael Hutchings
- Noncommutative Geometry
- Pieter Belmans
- Qiaochu Yuan
- Quomodocumque
- Secret Blogging Seminar
- Terence Tao
- The n-Category Cafe
- Timothy Gowers

### Physics Weblogs

- Alexey Petrov
- AMVA4NewPhysics
- Andrew Jaffe
- Angry Physicist
- Capitalist Imperialist Pig
- Chad Orzel
- Clifford Johnson
- Cormac O’Raifeartaigh
- Doug Natelson
- EPMG Blog
- Geoffrey Dixon
- Georg von Hippel
- Gordon Watts
- Jackson Clarke
- Jacques Distler
- Jennifer Ouellette
- Jim Baggott
- Joe Conlon
- John Horgan
- Lubos Motl
- Mark Goodsell
- Mark Hanman
- Mateus Araujo
- Matt Strassler
- Matt von Hippel
- Matthew Buckley
- Norbert Bodendorfer
- Peter Orland
- Physics World
- Reimagine Physics
- Resonaances
- Robert Helling
- Ross McKenzie
- Sabine Hossenfelder
- Scott Aaronson
- Sesh Nadathur
- Shaun Hotchkiss
- Stacy McGaugh
- Tommaso Dorigo

### Some Web Pages

- Alain Connes
- Arthur Jaffe
- Barry Mazur
- Brian Conrad
- Brian Hall
- Cumrun Vafa
- Dan Freed
- Daniel Bump
- David Ben-Zvi
- David Nadler
- David Vogan
- Dennis Gaitsgory
- Eckhard Meinrenken
- Edward Frenkel
- Frank Wilczek
- Gerard ’t Hooft
- Greg Moore
- Hirosi Ooguri
- Ivan Fesenko
- Jacob Lurie
- John Baez
- José Figueroa-O'Farrill
- Klaas Landsman
- Laurent Fargues
- Laurent Lafforgue
- Nolan Wallach
- Peter Teichner
- Robert Langlands
- Vincent Lafforgue

### Twitter

### Videos

# Category Archives: Quantum Mechanics

## The Problem of Quantization

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

## Fall Quantum Mechanics Class

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

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

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

Posted in Quantum Mechanics
Comments Off on Metaphorical Worlds Interpretation

## An Apology

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

Posted in Quantum Mechanics
Comments Off on An Apology

## Regarding Papers about Fundamental Theories

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

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

## What’s the difference between Copenhagen and Everett?

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

## Not So Spooky Action at a Distance

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?

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