Once the scale of the map is known, it is possible to measure the distance between two points. The easiest way to do this is to measure the straight-line distance using a ruler, then convert it ...

which is long in wavelength (and thus less accurate than light as a measuring tool). But if you are wondering what the insides of a CPU look like, right down on the nanometer scale, then check out ...

A brief exploration of different rulers and their uses. The other day, I answered a Facetime call to find a piece of raw meat ...