Light leaves every point of a subject in all directions. A lens collects some of that and reconverges it, and the entire craft is built on the properties and failures…
Source: Wikipedia
There is a category of institution that was built on a wrong explanation and worked correctly anyway, and it is worth understanding because the pattern recurs.
The wrong explanation,…
There is a useful principle in materials: if a substance behaves oddly in several unrelated ways, there is usually one structural feature responsible for all of them.
Wool behaves oddly…
There is a useful exercise in considering how recently an ordinary thing became ordinary, and fire on demand is the most striking example available.
Fire itself is extremely old. Reliable…
There is a way of analysing junctions that makes their differences obvious, and it is not the one most people use.
The usual way is to think about rules —…
Nothing here is about packing, which is a separate problem. This is about the evening before - the arrangements, the checks and the decisions that determine whether the departure is…