There is a widespread assumption about roads that is understandable and backwards.
The assumption is that the hard black surface is the road, and that what lies beneath it is…
A moving bicycle with nobody on it can stay upright for a considerable distance, correcting itself when pushed. Working out why took far longer than anybody expected, and the popular…
There is a difference between two ways of putting a mark on a surface, and almost everything about the history of writing materials follows from it.
The first is to…
There is a common assumption about concealment that is intuitive and mostly wrong.
The assumption is that hiding means matching — that the way to be invisible is to be…
There is a useful principle about signals that applies well beyond sound, and whistles are the clearest everyday demonstration of it.
The principle is that being heard is a matter…
There is a category of change so complete that the previous state becomes difficult to imagine, and street lighting is among the largest.
The state it replaced was real darkness.…