Black holes

Black holes are well understood by physicists, but I've read too many oversimplified, confusing, and seemingly-contradictory descriptions of them. Over time, I've settled on my preferred mental model of a black hole, one that usually helps me to work out the right answers to questions that non-physicists have about black holes. (An example of such …

Detecting MacBinary format

Classic Mac OS (the main Macintosh operating system from 1984-2001) had an interesting way of storing files. Each file potentially consists of two separate byte streams, known as the data fork and resource fork. Additionally, some important information was stored in the file's directory entry, using features of the Mac's native MFS and HFS filesystems. …

Isotopic mass curves

The mass number of a nuclide (isotope) is simply its nucleon count: the number of protons plus the number of neutrons. In the appropriate units, it's a good approximation of the actual mass. But it's not exact. If we graph the measured "isotopic mass" of the nuclides with a given mass number, say 37, we …