Are you a group selectionist?

Many scientifically-minded people believe in the evolutionary concept of group selection, without knowing that the thing they believe in has a name, or that it is, at best, disputed. Standard disclaimer: Just because I may suggest that something is scientifically true or natural, does not mean that I consider it to be morally good. So, …

Spooky action and quantum marbles

There's a phenomenon in quantum mechanics popularly known as "spooky action at a distance". One manifestation of it is known as the EPR paradox. It's usually explained using a thought experiment similar to the following. Spooky action at a distance "explained" Start with a particle that has a total "spin" of zero. Allow it to …

PKZIP “Implode” compression oddity

When I was researching old versions of PKZIP, I found that modern unzip programs aren't able to unzip the PKZIP v1.01 distribution file. Three of the member files inside the self-extracting ZIP file fail to decompress correctly. /cygdrive/c/dosprogs/ZIPTEST/101 $ unzip ../DIST/PKZ101.EXE exploding: README.DOC warning: 475 bytes required to uncompress to 873 bytes; supposed to require …

How fast does the Sun move?

How fast does the Sun move? I don't mean though the galaxy, or the universe, but simply how fast does it move across the sky? I've seen it stated categorically that the Sun moves at 15 degrees per hour. But, for one thing, 15.000000° can't be perfectly correct at all times, because the Earth's orbit …

Contaminating space

In April, 2019, Israel's Beresheet spacecraft landed on crashed into the Moon. It later emerged that it was secretly carrying a supply of live tardigrades -- microscopic creatures known for their hardiness. Naturally, many observers, joking or not, brought up the idea of accidentally contaminating the Moon with destructive Earth life. I worry about a …

An un-unzippable ZIP file

Apparently, I'm writing a series of articles about ZIP format. Here's a curiosity. I'm going to use the Info-ZIP zip program to make a ZIP file that the Info-ZIP unzip program cannot unzip. I'll only do things that should be benign, i.e. things that a normal user might conceivably do. This article assumes you have …

Survey of ZIP APPNOTE documents

[2019-09-21: I've edited this document to include some new discoveries.] I already wrote an article about the version history of the PKZIP software, so now it's time for one about the version history of the ZIP format. That sounds like it should be easy, but… not so much. I think the format versions are more …