The 2019 TLS certificate serial number mess

Remember the Great TLS Certificate Serial Number Brouhaha of March, 2019? Millions of website certificates have been mis-issued! Everything is insecure! The sky is falling! Revoke and replace, ASAP! I barely do, but I remember thinking it was a really stupid overreaction. Now I’ve gone back and reviewed what happened, and I’ll try to explain……

Does 0.999… equal 1?

Does “0.99999999…”, with the 9s continuing indefinitely, equal 1? Well, of course it does. This is not a new question. The internet was invented on a Tuesday, and by Wednesday afternoon half of its denizens were trying to explain to the other half why 0.999… does, in fact, exactly equal 1. The explanation, we’re told,……

Are humans descended from monkeys?

Are humans descended from monkeys? It’s an interesting question. Too many well-meaning scientifically-minded individuals are quick to reply with a defensive “No! We just have a common ancestor!” But that’s not a very good answer. It ignores the fact that the question is ambiguous, and that the definition of “monkey” is ambiguous. Sometimes the answer……

Computerized chessboard displays should be better

You can’t tell everything just by looking at a game position on a traditional physical chessboard. If you see: You can’t necessarily tell: the board orientationwhose turn it is to movewhat castling rights existwhich pawn, if any, can be captured en passant There are also lots of other things you can’t tell, such as whether……

Ideas for ISO 9660 CD-ROM format shenanigans

ISO 9660 is the filesystem format used on most CD-ROMs. It isn’t restricted to CD-ROMs, though. It can also be found in the form of an “.iso” image file, which might have been “ripped” from a CD-ROM (or other media format), or created with the intention of “burning” it to a CD-ROM. I researched the……

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……