Question

How is there such a thing as Negative Temperature?

Answer 1

In Kelvin?

Answer 2

yeah, negative energies and LASERs

Answer 3

dosent make much sense to me at the moment

Answer 4

There is no such thin as negative temperature/energy.We just take a measurement as standard limit and if the temperature/energy is below the standard limit it is represented in negative.For example:-standard limit of temperature is 0 degree Celsius(freezing point of water) but for scientific use we take kelvin(+273).

Answer 5

Negative temperature is a statistical mechanical concept - for more information see the book Física Molecular of Kikoin and Kikoin

Answer 6

ok so ive done a lil bit of research,
and it turns out that when there is an inversion layer (the electrons are more likely to be in the excited state ) this is called negative temperature. it kinda makes sense because heat will flow from the specie at negative temp.
It gets a bit confusing when you also have a high energy state (positive temp), because the high energy state will be receiving the heat flow form the negative temperature specie.

If a specie is in a negative temperature state it effectively has more energy that any positive state.

Without negative temperature , LASERs would not be possible

Answer 7

cool stuff