
 What Does Negative Temperature Mean? (Site not responding. Last check: 20071012) 
  Notice that with this definition, E is zero when half of the spins are up and half are down. 
  So we have created a system where, as we add more and more energy, temperature starts off positive, approaches positive infinity as maximum entropy is approached, with half of all spins up. 
  After that, the temperature becomes negative infinite, coming down in magnitude toward zero, but always negative, as the energy increases toward maximum. 
 math.ucr.edu /home/baez/physics/ParticleAndNuclear/neg_temperature.html (1149 words) 
