Over at Backreaction, Bee is running an advent calendar of her own, with amusing anecdotes about famous physicists. Apparently, it’s a good year for advent calendars.
A couple of days ago, her story was a famous one about Heisenberg nearly failing to get his Ph.D. because he disdained experiment:
Wien wanted to fail Heisenberg, but Sommerfeld, in whose exam on theoretical physics Heisenberg had excelled, put in a strong word for Heisenberg. Heisenberg passed the doctoral examination with the lowest possible grade
Between this, and my own advent calendar posts about historical physics, I got to thinking about the split between experiment and theory in physics, and wondering where it all went wrong.
Nowadays, we take a nearly absolute division between theory and experiment to be almost a given. Obviously, each side needs to know a little bit about the other– you can’t interpret data without some idea of what theorists are talking about, and you can’t make useful predictions without knowing what experimentalists can do– but the vast majority of physicists are primarily one or the other.
It wasn’t always this way, though. Newton was, in many ways, the father of physics as a mathematical science– he invented calculus in order to be able to do physics, after all– but he also did numerous experiments. Some of these are still pretty useful to think about– his optical experiments splitting and recombining white light, for example– while others seem more like the stuff of mad science and anything a reputable researcher would get up to, such as working a thin knife blade up behind his eyeball so he could describe the effects that he saw by pressing on different parts of the eye. Most of Newton’s contemporaries similarly dabbled in both experiment and theory.
At some point, though, the two began to separate. By the early 1900’s, you had experimentalists like Rutherford, who cherished a deep distrust of theorists (with the exception of Bohr, who got a pass for being a good soccer player), and theorists like Heisenberg and Pauli, whose negative effect on experiments was so infamous that one apparatus failure was jokingly blamed on the fact that he was changing trains in the same city at the time that it broke.
The question is, is there a clear point of divergence? If so, when? I suspect it would be sometime in the early 1800’s, because Faraday has a reputation as being a great experimenter but bad with math, but I don’t know enough about the history to have a complete picture. It could also be much later, though, because Fermi had a very god reputation in both experiment and theory. Or it could be one of those eternal struggles– some of the commenters on Bee’s post try to trace this back to Plato and Aristotle, but I don’t really trust any comparison going back that far. I’m not sure we have a complete enough picture of what they were up to to make useful analogies between ancient Greek philosophers and modern scientists.
(I also wonder if the Heisenberg story gets misattributed to Einstein, who was actually a good deal more practically minded than his popular image. His major contributions were in theory, but he also invented some clever experimental devices and techniques, including a type of refrigerator.)
So, I’m curious to hear what other people think, and if there are really good arguments one way or the other. Or, failing that, I’m always happy to hear more amusing anecdotes about experimentalists vs. theorists…