system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5. When laser pointers are pointed onto a far away building, why does the diameter of the light grow?

I've never understood how a laser pointer with a light no larger than 1mm in diameter, grows to ridiculous sizes when shined across long distances.

This is probably some basic rules of light, I simply just can't comprehend how this happens.
gpt
Laser pointers are not perfect lasers, an excellent laser is beyond the budget you have for a cat toy.

The laser diode is very small, and some photons that leak out are slightly off axis.  By the time you get far away, these tiny angular errors have accumulated into something visible.