persia7
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we know the entropy in each process increases is it true for absolute negative temperature?
a week ago scientist discover there is negative temperature,if you suppose there is, what is your answer?Naty1 said:
persia7 said:a week ago scientist discover there is negative temperature,if you suppose there is, what is your answer?
persia7 said:a week ago scientist discover there is negative temperature,if you suppose there is, what is your answer?
Well, they are metastable only in the sense that their environment is colder, thus they tend to cool (go toward positive temperatures). This is true for any system (positive or negative temperature), which is hotter than its surroundings.Cthugha said:2) Negative temperatures occur in metastable or quasi-equilibrium systems, NOT in systems which are in equilibrium, so you keep a state stable which is not the ground state. You may imagine such state as similar to the steady state of a laser which involves population inversion. Note the difference between steady state and equilibrium state! As these states are not the equilibrium ones, you do not run into trouble with thermodynamics.
persia7 said:the principle increasing of entropy is universal , please explain it in negative temperature.
QuasiParticle said:Well, they are metastable only in the sense that their environment is colder, thus they tend to cool (go toward positive temperatures). This is true for any system (positive or negative temperature), which is hotter than its surroundings.
Some systems (e.g. nuclear spins in magnetic field) can be decoupled from their environment so effectively that a negative temperature remains even days without any additional work.