A Hole Is Defined by What Is Not There
A hole is a hollow or opening. Physics and mathematics both give the word technical work to do.
A hole is a hollow space or an opening through something. It is a rare everyday noun naming an absence rather than a thing, and physics exploits this: in semiconductors a *hole* is a missing electron, and it is treated as a positively charged particle that moves, because the mathematics works out identically. In topology a doughnut and a teacup have one hole each, which is why the two shapes are considered equivalent.
- A hollow or opening. *A hole in the wall.*
- A golf target. *The eighteenth hole.*
- A missing electron. *Electrons and holes.*
- In a hole — in difficulty. *In a hole.*
- Old English — *hol*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | hole | A hole. |
| Plural | holes | Holes. |
| Verb | hole | Holed. |
| Adjective | holey | Holey. |
| Old English | hol | A hollow. |
- There is a hole in the fence.Opening.
- He holed the putt.Golf.
- A hole is a missing electron.Physics.
Holes in semiconductors
- An electron leaving its place creates a vacancy
- A neighbouring electron can move into it, shifting the vacancy
- The vacancy appears to travel in the opposite direction
- It is treated as a positive particle because the maths is identical
- Transistors depend on managing both electrons and holes
Old English *hol*, a hollow place or cave, of Germanic origin, related to *hollow*.
How can a hole be a particle?
In a semiconductor a missing electron behaves exactly as a positively charged particle would, so physicists treat it as one.
Why do topologists say a doughnut and a teacup are the same?
Because each has exactly one hole, and topology classifies shapes by properties that survive stretching.