Scientists Chill Atoms to Negative Temperatures

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Scientists Chill Atoms to Negative Temperatures

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German physicists have discovered that at negative temperatures, atoms are approaching infinitely hot.

Research physicists at the University of Munich in Germany have built what was previously only theoretically possible: a system with negative temperature. While absolute zero, the temperature of minimum molecular motion, is still unreachable, these scientists have pushed to the other side of zero and found a negative temperature system. Negative temperatures don't actually have "less" energy than zero, or actually take up some state "below" zero, but they do have some strange and bizarre properties. Whereas in a normal system atoms spread out evenly across all available states as energy increases, leading to an increase in entropy, in a negative system the atoms begin to occupy the maximum possible energy state at the same time - leading entropy to decrease as energy increases. This is the point where you've reached negative temperature. As one scientist put it, "the gas is not colder than zero Kelvin, but hotter. It is even hotter than at any positive temperature - the temperature scale simply does not end at infinity, but jumps to negative values instead."

Theoretically, this innovation could lead to more than 100% efficient engines, because of the way heat would flow around the entropy sink that is a negative system. "Heat would flow from a negative to a positive temperature system," said a study scientist, "because negative temperature systems can absorb entropy while releasing energy, they give rise to counterintuitive effects."

The authors' major hope is that the behavior of a negative system will lead to greater understanding of dark matter, the mysterious force that might be behind the expansion of the universe, because it appears that the "negative pressure" effect dark matter has is similar to what negative temperatures do. Any new developments will have to wait, though, because as it stands the negative system was stable for only hundreds of milliseconds - enough time to gather data and do little else.

Source: Ars Technica & Huffpost Science
Image: LMU / MPQ Munich

Permalink

Let the SCIENCE!!! Pics and quotes flow!

greater than 100% efficiancy? so instead of releasing energy into the environment it sucks it in? This kind of reminds me of that nethicite or whatever it was called from FF12.

I love how none of this actually makes any common sense. They have found a way to get past absolute zero without hitting it, it gets hotter than positive numbers could get, and it could lead to more than 100% efficient machines.
I love science.

NO NOT LISTENING! You can't do that it isn't allowed! Stop it now! PLEASE STAHP!

I don't even know what to think any more. My mind is blasted.

elilupe:
I love how none of this actually makes any common sense. They have found a way to get past absolute zero without hitting it, it gets hotter than positive numbers could get, and it could lead to more than 100% efficient machines.
I love science.

I'm pretty sure the issue is with interpretation, not the experiment itself.

But the thing is, "temperature" is basically defined as the kinetic energy of the particles. And therefore, the lowest possible temperature is the one where the particles are not moving at all. You can't "cool an atom below absolute zero", at least not if you still want to keep the same definition of "temperature" as we use when we say "Oh, it's 23 degrees outside".

Oh and why does this suddenly come to mind?

Bottom line...the scientists themselves don't know what exactly they have discovered so they'll look into it further while the media sensationalizes and misinterprets the research results. Nothing new.

Nothing to see here, citizen, move along.

PS: Not saying that we're never, ever, going to redefine "temperature". Science does redefine stuff to fit with empirical results. But, the current definition of temperature simply does not allow negatives.

I'm still not sure I understand the concept of negative temperature. To the study article!

My head hurts, I've been trying to understand how this works but I really can't. I guess quantum physics really wasn't for me.
Now if you don't mind, I'm going to get some ice for my headache.

Captcha: Get well
Aww... Thank you Captcha :)

This is slightly terrifying.

Wait. Doesn't this violate the laws of thermodynamics?

http://www.youtube.com/watch?feature=player_detailpage&v=5NylmdC_uEM#t=25s

That's what I love about science. Can't reach absolute zero? Fuck it, go negative and find everything goes wopsy trupy.

Thanks to four years of Mechanical Engineering I can safely say, if this isn't some weird April Fool's joke, this is huge.

TL:DR Somebody divided by zero again.
Why can't they just use "Equilibrium" instead? Okay, what they saying is: at maximum temperature you can keep adding energy to the atoms and they'll just send that energy right back out again. Essentially they'll become a better conductor than Ringo Star.

The reason this is "past zero" is because at the lowest temperatures, the molecules are also at the same energy levels simultaneously. But at the high end of the spectrum, we can keep going past that point. We can't get them that cold and keep taking energy, but we can get them that hot and keep adding energy.

This whole "negative temperature" thing is mostly just an artifact of one way to describe temperature at a quantum scale. It is not negative temperature in the conventional sense of temperature, nor even particularly related to that concept.

Vegosiux:

elilupe:
I love how none of this actually makes any common sense. They have found a way to get past absolute zero without hitting it, it gets hotter than positive numbers could get, and it could lead to more than 100% efficient machines.
I love science.

I'm pretty sure the issue is with interpretation, not the experiment itself.

But the thing is, "temperature" is basically defined as the kinetic energy of the particles. And therefore, the lowest possible temperature is the one where the particles are not moving at all. You can't "cool an atom below absolute zero", at least not if you still want to keep the same definition of "temperature" as we use when we say "Oh, it's 23 degrees outside".

Oh and why does this suddenly come to mind?

Bottom line...the scientists themselves don't know what exactly they have discovered so they'll look into it further while the media sensationalizes and misinterprets the research results. Nothing new.

Nothing to see here, citizen, move along.

PS: Not saying that we're never, ever, going to redefine "temperature". Science does redefine stuff to fit with empirical results. But, the current definition of temperature simply does not allow negatives.

The problem comes from the difference between classical notion of temperature and the technical terms of temperature in statistical mechanics. In statistical mechanics the functions also define the distribution of energy states and given a certain distribution the temperature term becomes negative, but this was generally ignored as it didn't seem possible until now.

In simple terms, they've not removed the heat energy they've rearranged it.

First step... reproducable results! Then start calling it something new discovered.

Well that's nothing-wait what?!?! Entropy isn't supposed to work like that O_O, wtf.

So, from my understanding (or lack thereof) it's not that there's an actual "below" absolute zero, but they changed the conditions or, basically, how the atoms acted when exposed to the same temperature. And when they reacted opposite than they would have under normal circumstances, they're calling it a pseudo-negative temperature.

Or maybe I'm out of my mind and have no idea what I'm on about. Either way this is interesting.

Okay, I think everyone needs to read at least some of
http://www.empiricalzeal.com/2013/01/05/what-the-dalai-lama-can-teach-us-about-temperatures-below-absolute-zero/

They've been doing things like this since the fifties. It's just that this time the news media picked up on it and keeps getting it wrong.

Or, as http://www.coffeeshopphysics.com/articles/2011-08/26_leprechauns_and_laser_beams/ puts it:

The laser in your CD player routinely breaks the supposed law that nothing can be colder than absolute zero temperature. (The actual law is that nothing can reach exactly zero. The laser strives toward zero from below.)

kajinking:
Let the SCIENCE!!! Pics and quotes flow!

Damn, must think of something else now...

Aha!

Oh come on, don't look at me like that. Someone had to do it.

wizzy555:

The problem comes from the difference between classical notion of temperature and the technical terms of temperature in statistical mechanics. In statistical mechanics the functions also define the distribution of energy states and given a certain distribution the temperature term becomes negative, but this was generally ignored as it didn't seem possible until now.

In simple terms, they've not removed the heat energy they've rearranged it.

That seems like a much better method of describing it. As personally I go by the definition of temperature: "Average heat of a system", which I would think most people would think of at first glance.

Still rather cool though, but I imagine it would require a better name though. Referring to it as a negative temperature is confusing. (Though I bet that any news article will still call it negative temperature. Sounds much more unbelievable)

elilupe:
I love how none of this actually makes any common sense. They have found a way to get past absolute zero without hitting it, it gets hotter than positive numbers could get, and it could lead to more than 100% efficient machines.
I love science.

Actually, it does make a bit of sense.

Above zero, atoms diffuse, which you can observe by dropping food dye in water.

However, temperature is a measurement of atomic velocity. That is, the faster the atoms move, the higher the temperature.

So, what happens when you play a video at -2x speed? It goes twice as fast as normal, backwards. Thus, intuitively, atoms at negative temperatures will undiffuse.

Which means they all start occupying each other -

... nope, stops making sense again.

However, if that does cause the insane heat that we're told it does, then yeah, I can see that creating > 100% efficiency engines.

So, would it mean writing a new law of Thermodynamics, or extending the 3rd?

Lord Kelvin must be spinning in his grave so fast that you could hook a generator up to him and call him a power station!

Science, cut that out!

ciancon:
Thanks to four years of Mechanical Engineering I can safely say, if this isn't some weird April Fool's joke, this is huge.

Exactly what I was thinking. If this is actually possible and becomes applicable then our long-term energy concerns look a lot less problematic.

someperson1423:

ciancon:
Thanks to four years of Mechanical Engineering I can safely say, if this isn't some weird April Fool's joke, this is huge.

Exactly what I was thinking. If this is actually possible and becomes applicable then our long-term energy concerns look a lot less problematic.

I wonder if there are side effects. 300% more efficient engines, but pre-natal exposure causes biotic abilities.

Ukomba:
So, would it mean writing a new law of Thermodynamics, or extending the 3rd?

It doesn't break the third law of thermodynamics, because that only says that you can't get zero temperatures. These guys got to negative temperatures by going through infinity, by being very clever with the definition of temperature and the idea of entropy.

I want to make it clear that they have not created anything with negative heat. This thing still has positive heat and positive energy.

Sounds more like they created antimatter to me... but what do I know.

Redingold:

Ukomba:
So, would it mean writing a new law of Thermodynamics, or extending the 3rd?

It doesn't break the third law of thermodynamics, because that only says that you can't get zero temperatures. These guys got to negative temperatures by going through infinity, by being very clever with the definition of temperature and the idea of entropy.

I want to make it clear that they have not created anything with negative heat. This thing still has positive heat and positive energy.

I didn't say it broke the 3rd, just that it might need to be extended to reflect this reversal. I don't know that it Breaks the 2nd law yet either.

Ukomba:

Redingold:

Ukomba:
So, would it mean writing a new law of Thermodynamics, or extending the 3rd?

It doesn't break the third law of thermodynamics, because that only says that you can't get zero temperatures. These guys got to negative temperatures by going through infinity, by being very clever with the definition of temperature and the idea of entropy.

I want to make it clear that they have not created anything with negative heat. This thing still has positive heat and positive energy.

I didn't say it broke the 3rd, just that it might need to be extended to reflect this reversal. I don't know that it Breaks the 2nd law yet either.

Well, if it ain't broke, don't fix it.

As for the second law, while they did manage to decrease the entropy of this supercooled whatever-it-is, the equipment they used will almost certainly have raised entropy in the surrounding environment, so the second law's fine too.

ritchards:
First step... reproducable results! Then start calling it something new discovered.

I agree. If so, let me be the first to claim

SORCERY! BURN THE FOUL BREAKERS OF GODS LAW BACK TO THE HELLS FROM WHICH THEY CAME!!!

Seriously could be pretty big if its repeatable and can be repeated cheaply enough to make it marketable.

Redingold:

Well, if it ain't broke, don't fix it.

As for the second law, while they did manage to decrease the entropy of this supercooled whatever-it-is, the equipment they used will almost certainly have raised entropy in the surrounding environment, so the second law's fine too.

Exactly. The 2nd doesn't say that entropy can't decrease on a local scale, it's purely global.

grey_space:

ritchards:
First step... reproducable results! Then start calling it something new discovered.

I agree. If so, let me be the first to claim

SORCERY! BURN THE FOUL BREAKERS OF GODS LAW BACK TO THE HELLS FROM WHICH THEY CAME!!!

Seriously could be pretty big if its repeatable and can be repeated cheaply enough to make it marketable.

You think they would have published it if it weren't reproducible? They would be the laughing stock of the scientific community if that were the case.

lacktheknack:

Above zero, atoms diffuse, which you can observe by dropping food dye in water.

However, temperature is a measurement of atomic velocity. That is, the faster the atoms move, the higher the temperature.

So, what happens when you play a video at -2x speed? It goes twice as fast as normal, backwards. Thus, intuitively, atoms at negative temperatures will undiffuse.

Which means they all start occupying each other -

... nope, stops making sense again.

It's simple, the atoms have joined the occupy movement:

They're just sick of those 1% dark matter elitists stealing all their energy, they did make signs to explain all this, but they're so tiny no one can read them without an electron microscope.

That said, I still haven't made it past Schroedinger's cat, so this is just more bafflingly impossible crap that makes me think the Large Hadron Collider is really just a huge LSD production machine.

Or as someone else said, the media are just mis-representing quantum physics again. Because trying to summarise several decades of thought experiments and advanced mathematics in a half a page article opposite pictures of celebrity botox comparisons is pretty damn hard.

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