In the news recently, over unity carnot engines anyone?
http://arxiv.org/pdf/1211.0545.pdf
Negative temperature
Lasers do this. It is called a population inversion. Most thermo text books make at least passing reference to it based on the fundamental definition of temperature. dE/dT IIRC.hanelyp wrote:What kind of energy do you need to expend to produce this pool of negative heat?
Engineering is the art of making what you want from what you can get at a profit.