Graduate school, by and large, and with the possible exception of Med School, is not about taking classes. Those letters "Ph.D." mean you’ll be a doctor of PHILOSOPHY, not of chemistry, or molecular genetics. The philosophy is the philosophy of independent inquiry. Learning to learn on your own and to conduct research into the unknown is the name of the game. Nonetheless, there are in fact classes and skills that even an advanced grad student or post-doc can take or learn that will be immensely practical for a future career as a technical professional.

"But I’m not ALLOWED to take classes as a post-doc," you may say. There are ways, particularly if you realize that you want to learn, not get credit for the class. When I was a post-doc, for example, I audited a number of MBA classes in the business school, completely off the books. Talk to the instructor beforehand, though.

Take statistics. Better still, take more statistics. I wish I’d taken more-it wasn’t even a requirement in my undergraduate major, and I only took one class in grad school. But, on the job, I use statistics every day and in every experiment. (In contrast, I haven’t used calculus, which I took a lot of, since I graduated.) You should learn about F-tests, t-tests, ANOVA, regression analysis, design-of-experiments, and confidence intervals at a bare minimum. You should also get some practice using some of the excellent statistical software packages available. If you’re good at statistics, people will come to you asking for advice…that is always good for your career.

Data analysis is very math intensive, and computers are essential. Get good at using them. Even if you don’t see yourself as a "computer programmer" per se, there are powerful analytical software tools that you should learn. Microsoft Excel is a good start, including writing macros. More sophisticated tools, like Matlab, are great next steps-they can help you bridge the gap from crunching numbers to writing code. Physics labs can be a great venue for learning these tools-look for an opportunity to manipulate some complex data sets-in an environment where you’ll get help with the software tools.

If you’re going into industry, you have to understand the basics of business. At a minimum, you should try to take one marketing class and at least one accounting class. The advice I received on marketing was to "take Marketing 101; everything else is pretty obvious or can be learned on the job." As for accounting, there are at least 2 flavors: financial accounting, which is how to read a balance sheet, and managerial accounting, which is about budgeting, project accounting, internal transfer costs, and the like. Both are excellent, and I suspect will be useful whether you wind up in industry, academia, or anywhere.

If you want to take something strange that appeals to you, go for it. However weird your rational mind may tell you some odd field may be, if it seems incredibly interesting or your intuition speaks to you, you should consider diving in. The cross-pollination of ideas from one field into another has inspired many or most of the biggest leaps forward in understanding the world.