A biologist, a physicist, and a mathematician are hanging out in the neighborhood.
They see two people enter an empty house, and an hour later, they see three people leave.
The biologist says “they must have multiplied.“
The physicist said “it must have been a rounding error.”
The mathematician groans and says “if one more person enters the house, then it will be empty”
A geologist walks by and asks “why are you looking at that house? There are some awesome rocks right at your feet”.