For everything we do, we feel temperature and it can explain to us the distribution of kinetic energy among the particles of the substance which means that the hotter the substance of location, the higher the average of the energy distributed is and when there is a drop in temperature, it means there is less heat to go around and the particles will have less energy pleading to a reduction of the average.
Temperature at absolute zero is when there is no energy to move the particle around. Absolute zero is at temperatures -273.15 degrees Celsius or 0 Kelvin and you must have had that temperature cannot go below absolute zero but science has shown that we can go below that we can go down to negative absolute temperature.
The third law of thermodynamics shows that we cannot reach absolute zero because it requires infinite energy. One can go very low to it but not reach it and scientists have been doing a lot of experiments helping them go down near absolute zero. Since we cannot reach zero how do we go to negative? Simple, another type of energy can make this happen.
With kinetic energy, it is close to impossible at least for now but for other factors like spin in quantum particles, it is possible when the spin creates another type of energy when placed in a magnetic field. The spin reacting with the field creates another source of energy and how aligned the spin is to the field determines the energy level and absorbing heat energy puts the spins on a higher rung on one another and vice versa.
The spins want to fall to Lower rungs so even when the particles reach the highest possible rung, there are forces that are willing to drag the spin to lower rungs. For negative absolute temperature to be reached, the energy is pumped to raise the particles to a higher energy level till it reaches a negative absolute temperature and this is how the lasers you have in your home works because as the energy drops it releases light but the energy needs to be pumped to maintain the negative absolute temperature.
A lot of scientist say that this doesn't count as a real temperature because it isn't stable and keeps dropping so the concept of negative absolute temperature is still controversial as numerous physicist still believe that it occurs only the law of thermodynamics is misinterpreted because while will negative absolute temperature be about hotter than hot. Anyway, which ever one you want to go with, it is fine. You can agree that we cannot reach absolute zero and you can also agree that we can reach absolute negative temperature but in all remember the laws of thermodynamics.
Reference
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