By the way, historically, classical thermodynamics was burdened with inconsistencies -- in the low energy range -- that were resolved by quantum thermodynamics.
Classical thermodynamics became self consistent when the third law of thermodynamics was added. The problem was that classical thermodynamics is not consistent with classical mechanics.
Classical thermodynamics is based on four fundamental laws (0,1,2,3), the third law being the last of the series. Statistical mechanics showed how classical thermodynamics is consistent with classical mechanics for high temperatures. There is no inconsistency with classical physics for an ideal gas. Boltzmann statistics governs the behavior of all materials at high temperatures and low pressures.
The major inconsistencies came about because of three things. First, the third law was inconsistent with classical mechanics. Second, the fact that thermal equilibrium exists is inconsistent with classical mechanics. Third, experimental fact that the black body radiation is finite.
The third law basically says that all systems in equilibrium have the same lowest bound in temperature, which is called absolute zero kelvin. There is no way to get a lower temperature using a finite number of cyclic processes. Scientists tried, and still try, to get lower temperatures than 0 K in equilibrium materials and can't do it.
One can achieve lower 'temperatures' in systems very far from thermal equilibrium. However, these aren't well-defined temperatures because thermodynamic temperature for system infinitesimally close to thermal equilibrium. When you hear about negative temperatures, the system that is being discussed is at best in quasi equilibrium. The excited material used in lasers can have a negative temperature, but this is not violating the third law because the excited material are far from equilibrium. However, why should any system ever approach thermal equilibrium?
This was solved when quantum mechanics showed how bound systems have discrete energy values. There is a ground state which is energetically far from the other states. So you can't lower the temperature so far that the energy of the bound system is below the ground state energy.
If there is no lower bound to temperature, then can always reach a lower temperature by emitting radiation into the vacuum. Furthermore, point particles of opposite charge could always emit radiation by get closer to each other. In classical mechanics, there is no smallest distance between point particles. So why are atoms with point charges ever at equilibrium? Alternatively, why do all particles have a finite size? Atoms shrink for all eternity, giving off electromagnetic waves! They should never settle to a finite size. Obviously, there is no such thing as thermal equilibrium. -Not-
Isolated systems have a tendency to asymptotically approach a state of thermal equilibrium. Boltzmann showed using classical mechanics that this state has a characteristic entropy. However, this entropy calculated by classical mechanics had no lower limit. This means that one can always make an isolated system that would absorb heat from other systems.
Again, quantum mechanics showed that given enough time a system that emits photons will reach an equilibrium. One couldn't lower the energy below the ground state energy.
The energy density of a black body can be determined from classical mechanics. The energy density of the black body radiation should be infinite. Further, there should be no upper bound to the frequency of the black body radiation at a certain temperature. This contradicted experimental measurements.
Quantum mechanics solved this by showing how the amplitude of a vibration is limited to discrete values. Energy is basically the square of the amplitude. So there was no way for a quantum mechanics system to have an infinite energy.
Anyway, the above is my interpretation of science history. Classical mechanics shows that there are no states of equilibrium possible. Quantum mechanics was necessary to explain why isolated systems approached equilibrium.
Some people claim to have extracted energy from the zero point radiation. Others here claim that this violates conservation of energy which is the first law of thermodynamics.
I won't make a stand right now on whether any of these innovators are right or not. However, I will correct big mistake that the skeptics are making. The first law of thermodynamics is not being challenge when they make a perpetual motion device.
A device that extracts energy from zero point radiation is not violating conservation of energy. The energy comes from the zero point radiation. Therefore, it is not violating the first law.
A perpetual motion device extracting energy from the zero point energy is violating both the second and the third law of thermodynamics. When the device does work, it decreases the entropy of the universe. Because the device is never close thermal equilibrium, one can always construct negative temperature states.
The inflating universe may be such a perpetual motion device! The universe before the canonical Big Bang extracted zero point energy. So energy was conserved. However, the entropy of the pre-universe decreased. Further, there were no bound states before the Big Bang (?). So there was no discrete energy states, and no ground state. So the temperature could decrease without limit. So the second and third laws were violated in the inflationary time.
So the first law of thermodynamics is fairly safe! The last two laws are on shaky ground <state>, maybe!
How am I supposed to know at face value when someone comes to me with a new theory?
