Black holes – supplement

Here are a few notes about black holes that I think are interesting, but didn’t fit in my previous post on the topic. What would happen if… I asked as an example question “What would happen if you tried to escort a small black hole into a large black hole?”, but I didn’t answer it.……

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……

Simple orbital mechanics

The Moon is slowly siphoning off the Earth’s rotational energy, in a phenomenon called tidal acceleration. This moves the Moon’s orbit farther from the Earth. According to Kepler’s laws of planetary motion, the Moon must orbit more slowly as it gets farther away. Well, which is it? Is the Moon speeding up, or slowing down?……

How to fix American football overtime

In American football, a neutral position is not really possible. There is no equivalent of a “jump ball” or a “face off”. One team, and not the other, must have possession of the ball, giving that team an advantage. This results in the overtime coin flip problem. I’ll assume that overtime is “sudden death”: The……

The half-life gap

If you sort all the nuclides (isotopes of elements) in order of increasing half life, there are a fairly steady supply of them (on a logarithmic scale) up to a half-life of about 10 million years. There are also about 250 that have a half-life so long that it has never been measured. (And for……