Tuesday, July 18, 2006

Beginning being presumptuous

What is Quantum and what is Classical? As presumptuous as it is, this blog will address my own and others' attempts to clarify the relationship. There are so many failed attempts out there that anyone who starts to think about the foundations of quantum theory had better be humble — but enough of that.

My own approach to understanding quantum theory is through quantum field theory. This has the simultaneous advantage and disadvantage that almost no-one goes this way, so much can be said that is new, but there is not much already as a guide. There's a substantial enough class of physicists who think that anyone who doesn't address quantum fields is not in the game, however (although quantum computing has changed the demographics somewhat), that it is perhaps compulsory to have an idea of what you would say about quantum fields. In any case, the standard approach, that we had better understand the quantum mechanics of finite dimensional phase spaces before trying to understand quantum fields, has not proved satisfying enough, so I have chosen to go straight to quantum fields.

Sadly, quantum fields have a fairly justified reputation for mathematical difficulty, which will have to be tackled. It's only when we find a way of explaining something to the proverbial person-in-the-street, as well as to physicists, that we can say with any justice that we understand it.

In the long and great tradition of blogging, this is not much thought through. Thinking through is for published articles — for me there are three (now five: January 2008), which can be found with some other comments through my Yale web-page.