September 03, 2017 at 10:50PM

Today I learned: 1) ...that I don't understand magnets. At all. What I am quite sure of is that magnetic fields are generated by moving electric charges. So when electricity flows, it generates a magnetic field. So far so good. But then what the hell is a static magnet? There's no charge flow in a refrigerator magnet! It turns out that I am right to be confused. There's a theorem from the late 1910s called the Bohr-van Leeuwen theorem (what awkward punctuation! Surely English can do better than that?) that says that when you apply statistical mechanics to a classical system of particles with charges and mass and all that, the net magnetization is *always* zero. In other words, classical physics *cannot* explain static magnets. So... what does? You guessed it -- quantum mechanics. For one reason or another, in QM, electrons end up generating a tiny little magnetic field around themselves. If you line up all the little magnetic fields, you get a big magnetic field. Why do electrons generate magnetic fields? Spin mumble mumble I have no idea. Now, the Bohr-van Leeuwen theorem only applies to non-rotating systems, so it's possible that classical mechanics can still explain, for example, the magnetic fields of stars and planets. But I can neither confirm nor deny whether it actually does. 2) Something else I don't understand -- and I'm throwing this out there to see if anyone does understand this -- what drives the colossal storms on Jupiter and other gas giants (but mostly Jupiter)? On Earth, hurricanes and typhoons are powered by warm water, which is itself driven by sunlight. But Jupiter is much farther than Earth from the sun, and it has much more powerful storms. Where does the energy come from? 3) Ledo Pizza now has a vegan pre-built pizza. It's easy enough to make one anyway, but theirs is better than any I've built.