Quantum entanglement breaks the second law of thermodynamics
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The Second Law of Thermodynamics roughly says that you cannot get something out of nothing. Since there is no free energy, for example, it is not possible to create a perpetual motion machine, although some at least curious attempts have already been tried.
Another aspect of the same law is the fact that energy always tries to counterbalance itself. If you have a pot of hot water and pour some cold water over it, you will end up with a warm liquid. If you want to cool or heat this water, you must have an external power source.
James Maxwell and his mental exercise
Everything was perfect until Scottish James Maxwell suggested an exercise that would confuse many people's minds in 1867: Imagine you have a container of warm water. This water has molecules that agitate at different speeds, the "hotter" ones moving quickly, while the "colder" ones moving slowly. Nevertheless, the average water temperature is warm.
Maxwell then suggested dividing this container into two halves, leaving only a tiny door, the size of a water molecule, open between them. Construct the door so that fast molecules are attracted to it and accumulate in one half of the container, and whenever a slow molecule gets close to the door, it gets passed to the other side.
That way, after a while, this door would have ordered the molecules to be fast and slow, meaning warm water would have turned to hot and cold water without the use of an extra source of energy. The Second Law of Thermodynamics is apparently violated.
Breaking the Second Law in Practice
Maxwell's idea is interesting, but a mental exercise. However, in 2010, scientists showed that it is possible to make a piece of plastic move with the random movement of air molecules, with a door similar to that proposed by Maxwell in his exercise.
The piece of plastic is placed at the beginning of a small ladder and suddenly begins to be pushed upwards. Whenever he does this, an electric door is closed just below him. The power used in this port is isolated from the rest of the system to make sure it does not interfere with the experiment. Over time, the plastic reaches the top of the stairs without external energy being applied to it.
Turning information into energy
After much study of these cases, physicists have come to the conclusion that these experiments depend on a lot of very accurate information about the system in which they are conducted. In Maxwell's mental exercise, you need to know the speed of moving molecules, and in the 2010 hands-on experiment, you always need to monitor the position of the piece of plastic.
All of these measurements depend on energy which, in turn, tries to counterbalance itself with the “free” energy that is outside the system. In other words, what happens is the transformation of information into energy: information about the position of the piece of plastic ends up being converted into energy that pushes it upward. That is, the Second Law of Thermodynamics remains intact after all.
The crazy things of the quantum world
Now scientists at Kyoto University and Tokyo University, both in Japan, have found that quantum mechanics brings some extra complications to these experiments and that once again the Second Law of Thermodynamics appears to be in fact being violated.
(Image source: Playback / arXiv)
To this end, they add to the Maxwell exercise a concept known as quantum entanglement. When two particles are quantumly intertwined, they behave as one, even though they are separated by a whole universe apart. Thus, it is possible to measure only one of them and obtain information about the other. And, as we saw earlier, information in this context is energy.
Therefore, in the above case, it would be possible to use energy to measure half the molecules and obtain information about all of them. In other words, it would be possible to split the container between “hot” and “cold” molecules using only half the energy required in the classic model.
For now, all of this is just mathematical calculus filled with Greek symbols in a scientific paper (PDF). But the authors' great achievement was to find that the Second Law of Thermodynamics also depends on quantum effects, and now the team is working on a way to expand it so that this revelation is also addressed.
According to the Technology Review website, this research will have important implications for all sorts of phenomena, from black holes and astrobiology to nanomachines and quantum chemistry.
Source: Technology Review