According to the basic laws of thermodynamics, if you leave a warm apple pie in a winter window eventually the pie would cool down to the same temperature as the surrounding air. For chemists and physicists, cooling samples of charged particles, also called ions, makes them easier to control and study. So they use a similar approach — called buffer gas cooling — to lower the temperature of ions by trapping them and then immersing them in clouds of cold atoms. Collisions with the atoms cool the originally hot ions by transferring energy from the ions to the atoms — much the same way a warm pie is cooled next to the cold window. But new research by UCLA physicists, demonstrates that ions never truly cool to the temperature of the surrounding gas. Also, very surprisingly, they discovered that under certain conditions, two final temperatures exist, and the temperature that the ions choose depends on their starting temperature. As one of the authors explains, this apparent departure from the familiar laws of thermodynamics is akin to our warm apple pie either cooling as expected or spontaneously bursting into flames, depending on the pie’s exact temperature when it is placed in the window. http://newsroom.ucla.edu/releases/u...ent-departure-from-the-laws-of-thermodynamics
The analogy of an apple pie spontaneously bursting into flames is fundamentally misleading, very bad. Nothing heats up spontaneously here - some stuff doesn't cool down in a straightforward manner, and the entropy of the system has a more complicated dependence on configuration than a simple mass times velocity in/out would suggest.
The gas constituents must have an isotropic velocity distribution function in order to have the same temperature in equilibrium. Any anisotropy and the equilibrium distributions won't be Maxwellian and the average kinetic energies be different (because the distributions are non-Maxwellian you can't strictly use the term 'temperature' anymore). See http://www.plasmaphysics.org.uk/maxwell.htm for more
Yeah yeah. Skip to the last para: " “Of course, this work does not violate the laws of thermodynamics, but it does demonstrate there are still some interesting, potentially useful things to learn about buffer gas cooling,” said John Gillaspy, a physics division program director at the National Science Foundation, which funds the research." Move along please ladies and gentlemen, there's nothing to see.