Nordfriedhof

The Mach number, almost as good as the Reynolds number, is one of the famous non dimensional quantities in physics. It is especially useful in fluid dynamics (as is the Reynolds number) because it allows you to perform experiments that are of a different size, different flow speed, using a different viscosity fluid, than the theoretical situation you are trying to replicate. However, even though these physical quantities are different, as long as certain dimensionless quantities match your desired situation, the experiment will be an accurate predictor.

Instead of having a gravestone among other gravestones, Mach has a pillar set apart from other gravestones. I assume that he's buried underneath. There are words on 3 of the four sides of the pillar. First, an explanation of who he was (as if that was needed!).

Second, the usual information. Interestingly, on German gravestones it often states what the person did, i.e., architect, artz (doctor), ingenieur (engineer), etc. Mach, of course, was a physicist and a philosopher.

The third side, not shown, was information about his son, who presumably is also buried here.

Arnold Sommerfeld was the other grave I wished to visit in Nordfriedhof. He was one of the founders of quantum theory, working with Niels Bohr to develop the Bohr-Sommerfeld quantization condition (one of the attempt's of "old quantum theory" to explain atomic spectra that didn't really work). His doctoral students include Werner Heisenberg, Hans Bethe, Wolfgang Pauli, Rudolf Peierls, and Peter Debye, many of whom won Nobel Prizes.

As I mentioned here, he my academic ancestor. You can my family tree here. You'll see that I currently have no PhD students, but my advisor, Burton Fried, has several. In addition, his advisor, Gregor Wenztel, also has several. And of course, his advisor, Arnold Sommerfeld, has many. And if you go back even further, you'll see that I am "descended" from great mathematicians like Gauss, Poisson, and Fourier. I don't presume to have anywhere their intellect, but it is nice to know that perhaps some of my skill comes from them. Certainly much of the way I approach problems is due to Fried, and I wouldn't be surprised if it is often like that.