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……

Points scored in overtime are not real points

I should know better than to write about college football, a sport that I pay little attention to. But it’s a particularly egregious example of an irritating phenomenon. On November 24, 2018, in American college football, Texas A&M and LSU were tied 31–31 at the end of regulation, and Texas A&M won in overtime. But……

The new record largest known prime number

A few days ago, the discovery of a new record largest known prime number (282,589,933−1) was announced, making my post on “finding” record prime numbers somewhat obsolete. I could update it, but that would be silly. Instead, I’ll discuss these record primes. It happens every couple of years: A new record large prime number is……