The other day, another young physicist came into my office to discuss his future.

Having finished several postdoctoral fellowships after completing his PhD at an Ivy League school, his prospects for getting a permanent position at even a mid-range university did not look terribly encouraging, and he was now looking for advice to make a transition to "the real world." A unique situation? Hardly: it was the second such conversation I had had that week.

How, you might ask, is this possible? Aren't all the demographics predicting a dire shortage of qualified applicants for faculty positions in our universities over the next few years? Perhaps.

But, as a friend of mine once put it, the daily fractional increase or decrease in the GDP per capita isn't going to affect the kind of day you're having.

The simple truth is that, although slowly improving, the job market for faculty positions in theoretical physics is pretty grim, particularly if one is determined to narrow one's choices by only considering positions at an accomplished research university with a strong graduate program.

The comparison is often made -- sometimes ironically, sometimes less so -- between theoretical physics and a monastic order: the single-minded dedication to abstruse investigations of the heavens and the fundamental order of things, the forsaking of worldly pursuits for intellectual and spiritual gain, the paucity of women present (although there are doubtless more women in a theoretical physics department than in a standard monastery, the male dominance is still striking), the shabby dressing -- and the list goes on.

And so it is not surprising that physicists themselves invariably talk of leaving the profession like leaving the priesthood -- would-be deserters periodically shuffle in to my office like renegade sinners, sadly admitting that they don't have what it takes to "stick it out."

But where do they go? Some move into teaching, others try to showcase their acquired software skills in a corporate environment. Many go back to university or community college to try and earn a more "useful" qualification.

For most theoretical physicists leaving the fold, however, the likeliest scenario is to take a stab at the cutthroat world of finance.

To the objective observer, this looks comical indeed: after all, the last place you might imagine some geeky, otherworldly physicist would be among the robber barons and rapacious tycoons of Wall Street. But, in fact, that's exactly where you should look for wayward scientists, for Wall Street was the single largest employer of theoretical physicists throughout the 1990s.

Mathematics, not surprisingly, is the key. The physicists that were being hired in droves by investment houses throughout the world were engaged for their unique combination of high-level mathematical skills and computational flexibility at a time when mathematical modelling of derivatives and other financial instruments was not as developed as it since became.

Typically, these quantitative analysts (or "quants" as they are informally called) are "back office" creatures -- away from the hustle and the bustle of direct interaction with clients and left alone with their complex mathematical programs to minimize risk and enhance return. Five or 10 years ago, all you needed was a PhD in theoretical physics or mathematics to achieve interest from keen Wall Street managers anxious to buttress their back office to compete with the other egghead-stocked firms.

Now, the situation is more complicated -- a PhD alone is no longer enough to gain interest -- most require a master of science in mathematical finance, or at least a few courses. Some clever university administrators have naturally seized on this as an opportunity: at the University of Illinois, students registered for their PhD in physics can be enrolled in their master in finance program and receive credit for their physics courses, thereby garnering a degree in finance for relatively little extra work.

Meanwhile, specialty one-year master's in finance have sprouted up across North America and beyond, giving would-be quants the qualifications they need to enter the trading game. Many entering students possess a PhD in math or physics.

I have a soft spot in my heart for physicists who leave academe for the concrete canyons of Manhattan, because I came perilously close to doing so myself five years ago. In my case, I was saved from a soulless, albeit potentially lucrative, career by the unique opportunity of starting a theoretical physics institute. Most, however, aren't so lucky.