There is a fact almost everybody knows and almost nobody can explain, which makes it a useful place to start.
The Moon presents the same face to Earth continuously. The…
There is a widely held picture of how concrete works, and almost every part of it is inverted.
The picture is that wet concrete is a thick paste which dries…
Source: Wikipedia
There is a habit of treating zero as obvious, on the reasoning that nothing is a perfectly ordinary thing to have none of.
The difficulty is not the concept…
There is a small set of sounds that produce a physical reaction in nearly everybody who hears them — a wince, a shudder, a reflex to cover the ears —…
The starting point is a discrepancy. Atomic bonds are extremely strong and the materials made of them are not, by a factor of ten or more - and everything below…
The conversion of sound to signal was solved early and has changed comparatively little in principle. Connecting any telephone to any other took a century of engineering. Here are fourteen…