Fusion isn't economical because "Currently, here on Earth the amount of energy you'd need to put into produce that kind of heat or pressure is much, much higher than what you get out in usable energy" [ http://www.popularmechanics.com/sci...ration/why-dont-we-have-fusion-power-15480435 ] but "a negative temperature is not colder than absolute zero, but rather it is hotter than infinite temperature" [ http://en.wikipedia.org/wiki/Negative_temperature ] hotter than infinity seems like it should be enough to achieve fusion economically!Drakkith said:No, negative temperature is a result of a system that has a limit on the number of high-energy states available. These are very specialized circumstances and the temperature becomes negative because of the relationship between energy and entropy. It doesn't have any bearing on fusion.
Normally fusion occurs at high temperatures but "You need a lower bound for the energy in order to get positive temperatures and an upper bound in order to get negative temperatures" [ http://www.quantum-munich.de/research/negative-absolute-temperature/ ]. We know a typical system with a lower bound fuses at high temperature and high entropy might a system with upper bound fuse at negative temperatures and low entropy?Drakkith said:Negative temperatures don't apply to fusion plasma since there are a near-infinite number of states available for the plasma. In other words, we can keep inputting energy into the plasma and the entropy keeps increasing. To reach negative temperatures, the entropy would need to decrease while the energy increases.
I feel like I'm not explaining myself; couldn't there be a point of such high energy and so little entropy that the atoms have no place else to go but will smush together?Vanadium 50 said:John, you have asked the same question three times. Are you going to keep asking it until someone tells you "yes"? Drakkith has explained why it is not three times. If you would like him/us to elaborate on the answer, please explain what parts are confusing you. But don't just start from the top again.
John d Marano said:I feel like I'm not explaining myself; couldn't there be a point of such high energy and so little entropy that the atoms have no place else to go but will smush together?
Negative temperatures are temperatures below absolute zero, which is the coldest possible temperature in the universe. In simple terms, negative temperatures occur when a system has more energy in its higher energy states than in its lower energy states.
Negative temperatures can be achieved by manipulating the energy levels of a system, such as using lasers to excite atoms to their higher energy states. This creates a population inversion, where there are more atoms in higher energy states than lower energy states.
Fusion is a nuclear reaction in which two or more atomic nuclei combine to form a heavier nucleus. This process releases a large amount of energy, which is what powers the sun and other stars.
In some ways, negative temperature can be seen as a precursor to fusion. When a system has a negative temperature, it means that the atoms are highly energized and moving at very high speeds, which is similar to the conditions needed for fusion reactions to occur.
While negative temperatures may seem like a step in the right direction for creating fusion reactions, they are not currently being used for this purpose. The extreme conditions needed to achieve negative temperatures are difficult to maintain and control, making it impractical for use in fusion reactors.