"RedAcer" wrote in message
...

How many do you know?

Scores. I've got a degree in Physics and spent several years working on
a PhD in low temperature solid state physics.

When the photon reaches a body and is absorbed by an atom how does is it
'know' if that body is hotter or colder than the one it was emitted
from. How does the absorbing atom 'know' the temperature of the body the
photon came from?

I am tempted to reply: "The photon and atom ask a passing PhD student." :-)

The photon and the atom only "know" the photon's frequency and hence its
energy. It is the difference between the absorbed photons' and emitted
photons'
energies which determines the objects change in temperature.

Cheers, Alastair.