The word “quantum” means a single share or portion. In quantum mechanics, this means that energy comes in discrete chunks, or quanta, rather than a continuous flow. But it also means that particles have other properties that are discrete in a way that’s deeply counterintuitive. Today I want to tell you about one such property, called spin, and the experiment that discovered it: the Stern-Gerlach experiment. (The goal of the original experiment was actually to test something else. But it was revealed later, after the discovery of spin by Wolfgang Pauli, that this is in fact what Stern and Gerlach were
February 2015
Astrophysics / cosmology / Physics / etc.
The Universe Is an Inside-Out Star
No, not really. But as we’ll see, it’s a useful analogy. Today we’ll learn about sound waves in the sun and how, if we imagine that the universe is the sun but inside-out, these are the same as the sound waves that filled the early universe. DISCLAIMER: This is a pedagogical exercise only! I am not claiming the universe is ACTUALLY an inside-out star or that scientists think of it as one. Sound Waves in the Sun I’m sure you won’t be surprised when I say that the sun is a complicated beast. A nuclear furnace burning at tens
Computer Related / Mathematics / numerical analysis / etc.
Tidbit: Radio Waves Bouncing Off of an F-15
I’m afraid I don’t have time to write very much this week. So instead, I leave you with a little hint of the sort of thing I’m thinking about. The above picture is from a paper I just read. It shows a simulation of radio waves bouncing off of an F-15 fighter jet. The simulation was effected by first building the jet out of many tiny pyramids linked together at the faces (shown on the left). Then, a set of five waves or so was allowed to exist inside each pyramid. When you take all of these waves together,
Uncategorized
The BICEP2 Result Was Just Dust, and That’s Okay
You may remember that about this time last year, there was a big hullabaloo because a research group from Harvard claimed that they had discovered primordial gravitational waves using BICEP2, their telescope in the South Pole. This was very exciting because, if true, the result would be extremely good evidence for a model of the early universe called cosmic inflation. (Cosmic inflation is mostly accepted by the scientific community, but it has some philosophical problems and is thus still a little bit controversial. The BICEP2 results would have ended the controversy once and for all.) Even better, the precise