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What 'Negative Temperature' Really Means
On Friday we discussed news of researchers getting a quantum gas to go below absolute zero. There was confusion about exactly what that meant, and several commenters pointed out that negative temperatures have been achieved before. Now, Rutgers physics grad student Aatish Bhatia has written a comprehensible post for the layman about how negative temperatures work, and why they're not actually "colder" than absolute zero. Quoting:
"...you first need to engineer a system that has an upper limit to its energy. This is a very rare thing – normal, everyday stuff that we interact with has kinetic energy of motion, and there is no upper bound to how much kinetic energy it can have. Systems with an upper bound in energy don’t want to be in that highest energy state. ...these systems have low entropy in (i.e. low probability of being in) their high energy state. You have to experimentally ‘trick’ the system into getting here. This was first done in an ingenious experiment by Purcell and Pound in 1951, where they managed to trick the spins of nuclei in a crystal of Lithium Fluoride into entering just such an unlikely high energy state. In that experiment, they maintained a negative temperature for a few minutes. Since then, negative temperatures have been realized in many experiments, and most recently established in a completely different realm, of ultracold atoms of a quantum gas trapped in a laser."
It's called 'mod down' not 'downvote' you idiot. Go back to fucking Reddit where you belong.
In the USA, it means its really, really cold, you'll have to dress well, including good gloves and hat. If there is any wind you'll wand to cover your face too.
and the air is very dry, inside, getting a humidifier is a good idea.. If your car or truck has been parked outside for a while you would need to start it and have it warm up for 10 minutes before driving off.
In the rest of the world its cold but bearable, since its just below freezing sidewalks may be slippery.
awesome, im totally buying that $2500 quantum volume knob from Monster Audio now. I bet it sounds amazing!
Mod me down, my New Earth Global Warmingist friends!
Yeah. Systems hate snobs and their feelings get hurt.
Hah, already got one. It goes to 11.
Faster! Faster! Faster would be better!
If 'nerds' had paid any attention to their thermodynamics/statistical mechanics class they would have already know all this and we would have been spared two frivolous posts in the front page.
Why are you being so negative?
Faster! Faster! Faster would be better!
Mine's even better, it goes to -1...
I don't use it anymore after I damaged physical reality on its first use.
layman
n.
A man who gets laid. Also known as a non-Slashdotter.
Systems with an upper bound in energy don’t want to be in that highest energy state.
Sigh...
Well, I concur, anthropomorphising these systems is a big problem.
You see: the matter and energy (no matter their colour - dark/white, orientation - up/down, flavour/charm/strangeness, etc) are freer and have more self-determination than any human being will ever have. They only obey the laws of physics, while the human beings need to obey heaps of others (e.g. did you ever see an electron being groped by TSA agents when passing through a semiconductor gate?).
Anthropomorphizing is degrading for physical entities and, for their sake, need to stop. Join the movement for upholding the inalienable rights of energy and matter before is too late!
Questions raise, answers kill. Raise questions to stay alive.
Yes, particles hate it when you anthropomorphize them.
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