February 10, 2016 at 02:32AM

Today I Learned: 1) There's a step of awesome above automatic watches -- the Atmos atmospheric-pressure-drive clock. This exquisitely constructed clock brand sits in a sealed chamber with ethyl chloride gas. When tuned properly, differences in ambient temperature cause the ethyl chloride pressure to increase and decrease, which winds a spring. It can run "for years" without human intervention. Related to the Atmos is the Beverly Clock, which is a single clock in New Zealand which has operated near-continuously (but not quite continuously) under similar principles without winding since its construction in 1864. While reading about the Atmos, I also stumbled on the idea of the torsional pendulum -- this is a pendulum in which the negative feedback that keeps the pendulum running is torsion rather than gravity. Imagine a pendulum made from string, with a long bar as a head. Now spin the bar. It will wind up the string, then unwind, then anti-wind, then un-anti-wind, and on and on for quite a while. Apparently these are more efficient than traditional pendulums for long-term use, though I don't know why. This TIL fact *also* brought to you by Anders Knight. How long can he keep it up? 2) The player ranking system in Go consists of many levels of kyu (or student ranks), on top of which are nine levels of dan. Today I learned the approximate meaning of a 1-dan difference in skill. Roughly speaking, a player one dan below his opponent should be able to win around 50% of the time when he or she gets an extra free turn at the beginning of the game. That's a big difference. AlphaGo, the Google's headline-making Go-playing program, has beaten the European Go champion, who is a 2-dan professional. It is scheduled to play a 9-dan professional sometime next month. Thanks to Robert Johnson and Chigozie Nri for teaching me this! 3) Apparently doctors don't like electronic record-keeping systems. Really, really don't like them. As in, electronic record-keeping systems are one of the most consistently-complained-about parts of general practitioners' daily work. I find this somewhat flabbergasting.