## Saturday, March 22, 2008

### Sidney Coleman: Physics 253 videos

See 54 videos from Sidney Coleman's 1975-1976 legendary Harvard lectures of Relativistic Quantum Mechanics, Physics 253.
Take a random lecture, for example the first one, and watch for a few minutes. Note the precise moment when he makes a joke or lights up each cigarette. These moments were optimized and kept constant for decades. ;-)

I am not even sure whether he would be allowed to light up the cigarette these days. I doubt it. On the other hand, he would be encouraged to bring his snowboard in the classroom and say that quantum field theory is in trouble and it is a result of oppression by white males - just like what the only student of Coleman's who didn't attend SidneyFest thinks.

Hat tip: Clifford Johnson who thought that Coleman was chewing chalk; the matches didn't help him to crack the puzzle ;-)

Sidney Coleman: Quantum mechanics in your face (1994, flv)
It's about characteristic features of quantum mechanics, entanglement (GHZM argument sold as pedagogically superior over Bell's argument), interpretation etc.

Around the 35th minute, Coleman is puzzled, just like your humble correspondent, why people - popular and even "not so popular" book writers :-) - get so confused about such a simple point and write whole books about "non-locality of quantum mechanics", something that clearly doesn't exist when you think about these setups properly. His answer, just like mine, is that secretly, in their hearts, they believe that it is classical mechanics. And they want to explain the new (quantum) theory in terms of the old (classical) one even though the only correct approach is the opposite one. That's why we shouldn't really talk about the interpretation of quantum mechanics because it is an inevitable part of the picture; we should talk about the interpretation of classical mechanics as a limit of the full theory.

I not only agree with all of his physics but find his jokes cool, wise, and relaxing. He politely asks those who didn't understand the first transparency to leave the auditorium. Then he compares native Americans and deers' intelligence to get a point through. He uses a Dr Diehard whose brain turned off once someone wrote a quantum mechanical equation - much like Coleman's brain turns off during string theory seminars :-) and so on.

Ludwig Wittgenstein and collapse

The punch line is absolutely hilarious. Philosopher Wittgenstein asked why did people say that the Sun orbits the Earth. He was told that it was because "it looks like the Sun is orbiting". Wittgenstein asked: "Hmm, and how would it look like [if it looked like] if the Earth revolved around the Sun?" :-)

Wittgenstein was referred as "one Jewish boy" in Mein Kampf, a book written by his classmate. Adolf Hitler hated him and he could become anti-Semitic because of him. Click for more details.

Coleman's point is that the same holds for the so-called "collapse" of the wave function (and also many other cases of incorrect dogmas held by various people). People think that there is a collapse because it looks like that there is a collapse. ;-) Coleman encourages everyone to think seriously about the possibility that the opposite answer is true, namely that the world is described by causal (= subluminal signals only) probabilistic laws of quantum mechanics without any collapses. And your humble correspondent encourages you to do the same thing. How would such a world look like? It would look like the real world. Welcome home. ;-)

And that's the memo. :-)

Finally, without any new comments:
Videos from Sidneyfest 2005