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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.
Negative temperature is a concept in thermodynamics where the temperature appears to decrease as the energy of a system increases. This is counterintuitive to our everyday experience where temperature increases as energy increases. Negative temperature can only exist in certain systems, such as those with a limited number of energy levels.
Negative temperature is often associated with systems that have a negative entropy. This means that as the energy of the system increases, the number of possible microstates decreases. In other words, the system becomes more ordered and less chaotic. This is in contrast to positive temperature systems, where increasing energy leads to an increase in entropy.
While negative temperature may seem like a theoretical concept, it has been observed in certain physical systems, such as ultracold atoms and nuclear spins. However, these systems are highly controlled and not representative of everyday temperatures. Negative temperature is not possible in our macroscopic world, as it violates the third law of thermodynamics which states that the entropy of a perfect crystal at absolute zero temperature is zero.
Negative temperature has been studied in relation to understanding and manipulating quantum systems. It has also been proposed as a means for creating ultra-efficient engines and refrigerators, as well as for exploring the behavior of systems with negative heat capacities.
One of the main challenges in studying negative temperature is the difficulty in creating and maintaining the necessary conditions for it to exist. Additionally, some theories and models have limitations in their ability to accurately describe and predict the behavior of systems with negative temperature. Further research and advancements in technology are needed to better understand and utilize this concept.