June 11, 2016 at 02:05AM

Today I Learned: 1) The number of possible pairs of objects from a pool of N objects, with replacement, is the sum of whole numbers up through N-1. Exercise for the reader: Why? 2) Tel Aviv students have demonstrated a method of extracting RSA encryption keys from a computer by monitoring it with a microphone, at a distance of a few meters. I don't know most of the details, but they track very high-frequency sounds given off by the computer's solid-state electronics, mostly capacitors and solonoids and other things that have to work hard to keep voltage levels steady. There's a delightful FAQ here: http://ift.tt/1UrENrO 3) Swiss PhD students make about as much money as American postdocs. Just saying. This fact brought to you by: Mengsha Gong