I like boundaries. And for me certain disciplines require the rigor of definition. Maybe I picked up that persnickety habit from engineering school. I remember a particular class that I took called ‘The Physics of Semiconductors’.

When an electron moves through a semiconductor its absence leaves a hole. And that hole is just like any other hole – meaning the absence of something – yet however in the physics sense, that electron hole is treated as a true entity. Namely that it has quantifiable properties (namely a positive charge) much like the electron (negative charge) that vacated it.

A hole that is –  but isn’t.