Let me give you my "Mental Model."

There is no such thing as "cold."
There is no such thing as "heat." (there is infrared radiation--i.e. a
frequency(s) of vibration of atoms)
Cold is the absence of heat, absolute cold (absolute zero) is a single
measurement of one state of heat (vibration/movement of atomic
particles)--NONE!
Heat (hot) is really a measurement of the state of exicted atomic/sub-atomic
particles movement, and of that movement producing "heat" through the
friction produced by the movement of these atomic particles...

Next, there is no such thing as "time!" Time is simply a measurement of
movement! Indeed, our time is based on the rotation of the sun and
planets... (atomic time on the decay of a radioactive substance--but again,
physical change and movement!)

I realize that specific "mental models" have been created, taught, adopted
and followed (too religiously if you ask me!) for discussing and describing
"radio." However, most of these are far from "real things!"

Warmest regards,
John