Negative kelvin temperatures

A lot of people say humans are monsters, or that our lives are futile and meaningless. A lot of people say we do more harm than good, and that humans are nothing worth admiring or celebrating. Well I say fuck those people, because we've just discovered temperatures lower than absolute zero. We have found a way to go colder than a total lack of energetic behavior in the constituent particles that make up matter. Not only that, we didn't just theorize it, we actually did it in a lab, with real gas producing real negative kelvin temperatures. We as a species saw nature telling us something couldn't be done, and we promptly told it to go fuck itself. If that doesn't tell you everything that needs to be said about the value of the human race, I don't know what will.

Yes I know I'm severely late to the punch on this, and yes, I also know that you can't technically go "colder" than absolute zero since negative kelvin temperatures loop back around and produce heat, but I only found out about this recently, and the more I read about it, the more it makes me appreciate my species. I mean wow. If this isn't a Crowning Moment of Awesome in human achievement, I will promptly smack a bitch until it is.

edited 9th Sep '13 8:08:10 PM by KSPAM

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This is all very confusing, but it's my understanding that the hypercooled substance has heat energy in a way that it gives a negative kelvin reading, even though it's actually warmer than absolute zero, because absolute zero blah blah complete absence of heat.

So basically, we found a hole in the Kelvin scale.

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From my understanding (meaning this is all gonna be in layman's terms, most likely), it's like a loop. Going beneath absolute zero just creates negative energy, hence leading to negative momentum, and probably negative mass and density, meaning it's basically the same as normal matter... but in reverse. Meaning it still gets hot. So basically, it loops around itself, and absolute zero (along with the hypothetical "absolute hot") are as far as you can go before it loops back around on itself.

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No, Paradox is right. The catch is that temperature isn't expressed in terms of kinetic energy, but the relation between energy and entropy. In a classical positive-temperature system, adding energy will increase entropy — but negative temperature systems screw with quantum phenomena in a way that adding energy decreases entropy and can thus shove the relation we use to define temperature below zero.

Basically, temperature is proportional to the partial derivative dE/dS, where E is energy and S is entropy. To oversimplify, negative temperature happens when you screw with quantum constraints so entropy acts different (usually by rigging a system to have an easily-reached physical cap on its maximum energy) — not energy. It's not negative energy or negative mass or anything by any stretch. Actually, negative-temperature systems are not only hotter than absolute zero, but hotter than any positive-temperature system because the way entropy gets screwed with causes energy to flow out to any positive-temperature system.

It's still interesting, just not that kind of interesting.

edited 9th Sep '13 9:14:45 PM by Pykrete

... Sorry, I must have been getting that mixed up with some of the reading I was doing on negative energy and the Dirac sea earlier today. I swear, some of this stuff just goes right over my head O_O

Not that wikipedia is that great at explaining this shit that makes sense to anyone without a phD. Anyway, thank you for clarifying that for me, I appreciate it.

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I don't think the theory you outlined in your post implies the existence of any 'absolute hot'.

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It's not related to this particular discovery, no, but it's been talked about for a while. In a purely hypothetical sense, of course. Although, if an "absolute hot" does exist, the Planck temperature might be a good contender, considering that's the point where things get so hot the contemporary laws of physics start breaking down.

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Yeah, the key idea here isn't really that, so much as you cheese quantum constructs to rig a system that beyond a certain point loses entropy as you add more energy (usually with a system that has easily-accessible upper bounds of energy). That just incidentally happens to throw a negative sign in how we define temperature, which is weird and has some odd consequences (energy always wanting to leave, even into higher-energy systems) but as far as layman's terms go doesn't really mean what it looks like.

Yeah. It's not exactly cold per se, but the fact that we managed to basically turn the normal laws on their heads and create a system where entropy is all topsy turvy is still impressive, even if absolute zero is still technically as cold as you can get. I just like to refer to it as "colder than absolute zero" (even though it's hotter) because it sounds more impressive and takes less time to get across how amazing this is.

edited 10th Sep '13 1:03:47 PM by KSPAM

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So apparently it's because there's a maximum energy capacity, preventing more thermal energy from flowing as it should?

edited 10th Sep '13 1:26:37 PM by Trivialis

So... what does this actually mean?

"It's so hard to be humble, knowing how great I am."

There's a Planck Temperature too? Just how many of the universe's operational limits did that man find?

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Yeah, 1.416785×10^32 kelvin. It's about as hot as our current understanding of physics will allow.

@Mukora: It means entropy can go fuck itself

In more practical terms, it basically means that negative kelvin gases produce what experts like to call "a fuckton more energy" than matter with a positive kelvin temperature, meaning they potentially have applications as fuel and such wonderful things.

edited 10th Sep '13 1:51:18 PM by KSPAM

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So not time travel.

Damn.

"It's so hard to be humble, knowing how great I am."

Sorry, but you're not gonna be seeing that anytime soon (or at all) unless you're into one-way trips to the future, because traveling backwards in time defies all the established laws of physics as well as common sense. The universe abhors a paradox, as they say.

This isn't to say that at some point in the future it might become possible, but from our current understanding, it's not just impractical, it's impossible. No one knows how the universe would cope with the paradoxes created by traveling backwards in time, but the most likely answer is... it doesn't.

edited 10th Sep '13 3:15:03 PM by KSPAM

I've got new mythological machinery, and very handsome supernatural scenery. Goodfae: a mafia web serial

Sssssoooorta. Negative temperature at the moment is mostly just a quantum physicist's party trick. Outside of lasers, it mostly only exists on a quantum scale, and its properties aren't really all that useful at that scale — especially compared to the energy input they require to get to their key quantum states.

They don't really produce all that much energy. Being "hotter" has nothing to do with how much energy is in the system — it's really just a way to describe its tendency for energy to always flow outward regardless of the surrounding energy density (until the entropy changes enough to zero out again and return to normal mechanics). But since the way you get there is usually by hard-capping the maximum energy of the system somehow and playing with how it acts at that artificially-set boundary, you're better off just burning/fissing/fusing something if you want to actually put out a shitload of energy. We can already do that easily enough that containment and politics are a bigger concern than throughput.

One thing we are thinking about using it for is an RF amplifier. Strong RF pulses can kick an antenna's electrons (themselves a kind of quantum system with easily-controlled energy levels) into negative temperature, and spin resonance winds up emitting energy instead of absorbing it. But the effect is very small-scale and of more use in delicate signals than macroscale power grids.

edited 10th Sep '13 4:50:20 PM by Pykrete

Pykrete: Demonstrating why KSPAM is an English major since 2013

Seriously, from now on I'm directing all of my science and mathematics related questions to you, because you clearly know much more about a lot of this stuff than I do. It's still hella cool, but I just wouldn't get it otherwise

I've got new mythological machinery, and very handsome supernatural scenery. Goodfae: a mafia web serial

Well, according to general relativity, supposedly if you built some very long, very massive, very dense bar of material and spun it very fast, it would create a sort of twisted spacetime vortex around itself to the point where you could approach close to it and then move away in another direction and find yourself in the past. Also, entirely new things might come out of the vortex that never went in to begin with and have no causal source in our timeline at all.

Quantum physics has issues with stuff appearing out of nowhere, though, so it might turn out that unified field theory will somehow stop these sorts of devices from working.

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Cool !!!

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edited 11th Sep '13 3:25:10 AM by John6969

So now we can actually have water so cold it anti-boils instead of freezing?

"And as long as a sack of shit is not a good thing to be, chivalry will never die."