In contrast to Hilzoy, Kevin Drum is wondering why quants in finance all seem to be ex physicists not ex mathematicians.
Overbye suggests a couple of possibilities. #1 is the glut theory: "Physicists began to follow the jobs from academia to Wall Street in the late 1970s, when the post-Sputnik boom in science spending had tapered off and the college teaching ranks had been filled with graduates from the 1960s. The result, as Dr. Derman said, was a pipeline with no jobs at the end."
#2 is the affinity theory: "The Black-Scholes equation resembles the kinds of differential equations physicists use to represent heat diffusion and other random processes in nature. Except, instead of molecules or atoms bouncing around randomly, it is the price of the underlying stock."
Those both sound plausible, if incomplete, so here's another thing to think about. Even among the number crunching set, physics has a reputation as the most aggressive, male dominated branch of geekdom: only 14% of physics PhDs are women, the lowest of any of the sciences. (Math is pretty male dominated too, but pales compared to physics: 29% of math PhDs are women.) If the first thing that "aggressive and male dominated" reminds you of is thebig swinging dickworld of high finance, give yourself a gold star. Call this the testosterone theory: physicists are attracted to Wall Street because they like the atmosphere.
I don't agree with Overbye's theory No. 1. Math funding has shrunk and shrunk as computer scientists ate mathematicians lunch. That's a huge glut.
I think your big swinging dick theory is closer to the truth. I have 2 ideas.
1) math has become so absolutely abstract that you can't convince even idiot wall street CEOs that it has something to do with the real world. Mathematicians have a problem, they can't explain the issues addressed decades ago, which suggested the topics studied by their advisor, which have something to do with their research. Pure math has just gone so far out there into the barely imaginable that mathematicians can't understand what mathematicians in other fields are saying.
In contrast physics is tied down to the real world so there isn't such a profusion of incomprehensible equations.
2) Given the collapse of funding, public interest, everything that afflicts pure math the best mathematicians aren't going in to pure math. This was already true when I graduated in 1982. Pure math skill brain power might be a great way to lose hundreds of billions, but it impresses people.
3) my main theory. There is a very clear hierarchy in physics with particle theory the tip of the pyramid. Basically, physicists agree that the really important problems (as in mathematical problems) are few. There is very little room at the top. So physics generates a few superstars whose work on the core issues interests and convinces the profession and many wannabees.
Evidence: Bill press (full prof. at Harvard) said, when you're in graduate school you will be interested in two topics -- particle theory and the one you will actually work on.
Physicist turned biologist (forget his name) "There aren't enough problems in physics and I'm not going to be the one to solve them."
In mathematics one can be the worlds leading expert on a micro field which no one cares bout. Math is free to go where the mind wanders, so you can wander away from your competitors without loosing face.
In physics many are called but few are chosen. Thus physics exports ultra competitive people with damaged egos.