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Atoms Reach Record Temperature, Colder than Absolute Zero

Absolute zero is often thought to be the coldest temperature possible. But now researchers show they can achieve even lower temperatures for a strange realm of "negative temperatures."

Oddly, another way to look at these negative temperatures is to consider them hotter than infinity, researchers added.

This unusual advance could lead to new engines that could technically be more than 100 percent efficient, and shed light on mysteries such as dark energy, the mysterious substance that is apparently pulling our universe apart.

[Gee, are they not admitting the existence of "Zero Point Energy"?]

read more http://www.livescience.com/25959-atoms-colder-than-absolute-...

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This is a big deal.

Thanks for posting this.


I try to change people every day. Do You?

deacon's picture

time for a better guage?

like one that goes lower

If we deny truth before your very eyes,then the rest of what we have to say,is of little consequence

Negative temperature misleading

The concept is misleading, IMO. What they did discover is much more remarkable, in fact.

They created an energy state which is opposite to a standard energy state. I suspect this can be done at much higher temperatures too.

They didn’t really get close to absolute zero in that, a Bose-Einstein condensate never manifested, something Schrodinger would insist upon. ;)

They simply got them as close to being still as was practical to watch them moderately well.

The implications of such a field are astounding. It’s sort of an "entropy sink".

Just open the box and see

the thermodynamic temperature

the thermodynamic temperature T is given by

T == dE/dS where dS is not zero

So they are describing

a negative change in Energy and a positive change in entropy
a positive change in Energy and a negative change in entropy

By reducing the entropy through adding constraints while the energy stays the same could be a "negative" temperature.

Some molecules reduce their entropy while increasing their energy.

It seems misleading to refer to this as below absolute zero.

Perhaps thermodynamic temperature is relative to the system studied and the reference to absolute zero a misnomer.

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both temperature and pressure are relative.

when I pull a high vacuum on a system it is a high negative pressure.
it seems to me that many if not most discussing this subject are using the words enthalpy and entropy like they are interchangeable.
voltage and pressure do not flow, voltage or pressure difference (delta T) causes flow. this would be an example of entropy.

I was taught that heat energy is what keeps electrons in their orbit. the more heat content, the higher the orbit and vice versa. this makes intuitive sense.
today it would seem that people think the atoms are both spinning round and round and vibrating? or buzzing? and the vibration is the heat energy? Hmmmm...

you might like this.


Thanks for the tune

You make a good point.

Stuff 'wants' to flow from high pressure to low pressure. Leave the valve closed and that potential to create heat or work is unrealized.

Buzzing atoms are little antenna emitting and absorbing radiation. If more radiation is emitted than absorbed the atom gets cooler.

The atoms have kinetic energy plus the energy of their orbiting electrons plus each bond in say water is like a little spring and mass system, plus the nuclear vibrations and interactions all comprise the internal energy

We can measure the change in energy and call it Heat capacity. We can change the energy with a heat flow.

Bottom line this changes nothing and our beer can still be cooled.

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That’s my guess. Using a "temperature" in the test system, they infer a "temperature" scale. I believe its much more than that, though, and has implications for any energy based system.

Just open the box and see

Found a better article

Here's the Cliff Notes version. This is the first time "negative temperatures" have been attained in a gas. [Neg. temps in other modes were produced as early as 1957. -jd] They did it with gas by constraining the individual atoms of potassium into carefully calculated lattice patterns by means of magnets and lasers.


Update: I found the press release for the non-scientific media. It is excellent.


Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln

Excellent article

The press release in your update was great. I can almost sort of understand what is happening. Physics is so amazingly cool!

They are basically saying

They are basically saying that the second law of thermodynamics does not hold. The second law stems from statistically simplifying matter - in nature it generally does exist in a state which can be accurately described through statistical averaging.

They changed this by confining the "gas" into a very small area using magnetic fields and lasers (i.e., it isn't touching anything which can transfer its energy to raise the temperature of the gas). As a gas comes closer together by reducing the temperature, it tends to repel due to the intermolecular forces and internal energy - what we observe as pressure. They used lasers to alter the alignment of these particles so that they attracted rather than repelled in addition to reducing the temperature and confining it with the magnetic/laser barrier.

In nature, these atoms would be randomly aligned and thus some would be repelling each other and some attracting - this random arrangement is accounted for through statistical averaging. But the random arrangement results in molecular orientations which tend toward repulsion. In stead, these are all lined up like the atoms/molecules in a magnet (very very very unlikely in a random arrangement).

Just my two cents.

Well done.

Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln


I found the article, but it is not free. Here is the abstract. To me it is just Greek.

Absolute temperature is usually bound to be positive. Under special conditions, however, negative temperatures—in which high-energy states are more occupied than low-energy states—are also possible. Such states have been demonstrated in localized systems with finite, discrete spectra. Here, we prepared a negative temperature state for motional degrees of freedom. By tailoring the Bose-Hubbard Hamiltonian, we created an attractively interacting ensemble of ultracold bosons at negative temperature that is stable against collapse for arbitrary atom numbers. The quasimomentum distribution develops sharp peaks at the upper band edge, revealing thermal equilibrium and bosonic coherence over several lattice sites. Negative temperatures imply negative pressures and open up new parameter regimes for cold atoms, enabling fundamentally new many-body states.


Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln

Hmm negative temperature and negative pressure.

And big promises. Sounds like their looking for funding.

I maybe wrong, it's happened before. But it sounds fishy.

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Sorry, I'll stick with the third law of thermodynamics

And the second, for that matter.

Attaining a temperature of absolute zero involves getting a perfect crystalline structure in a state 100% devoid of entropy. This is quite difficult to do in a universe in which every single event that occurs increases the amount of entropy. Hence the third law, which can be paraphrased "It would take an infinite number of steps to achieve a temperature of absolute zero."

Attaining a temperature state below absolute zero means that entropy is actually decreasing in that matter; i.e. time would be moving backwards. Is it possible that physicists made time work backwards in a couple of atoms? I guess, but I don't believe they did. Much more likely that their experiment doesn't mean what they think it means.

silly me, I thought it had to do with removing all heat!

and now I learn that entropy can decease....
don't tell me...let me guess.... ECTROPY!

The way they achieve

The way they achieve decreasing entropy is by constraining the system somehow, so that at some point it cannot take on more energy. Such a system does not break the laws of thermodynamics; it sets up conditions where those laws do not apply.

Having said that, I confess that I cannot understand the article. I am googling for a better one.

Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln

Right, meaning that the

Right, meaning that the second law is really just a phenomenon of randomly organized atoms. Meaning, it doesn't really exist purely, only in certain scenarios - the scenarios which are most likely to occur naturally.

IOW, the second law is broken.

Not that new

Nuclear and electron-spin systems with so-called "negative temperature" were produced as early as 1957.

Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln

so, you don't have a problem with the scale going negative?

I don't either, but then I was not taught that heat was vibration or that entropy was chaos.
you are of course aware a new form of matter was discovered....right?

Entropy is defined by the

Entropy is defined by the number of micro-states a system can take on. In the case of "negative temperature," some states are constrained or disallowed by some clever method. The structure of the thing takes some of the chaos out of it.

I do not know what the scientists did. I cannot make heads or tails of the article. I am googling to see if I can find one written by a scientist.

Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln

that is not what I was taught.

entropy simply means that nature demands equilibrium. this is why you cannot get water to run uphill.
or a lower pressure to flow to a higher one.
I have only recently been made aware of the word ectropy.
forgive me.


Gravity is the reason water is hard to pump uphill. Entropy is why it is hard to separate cream from coffee once they are mixed. "Mixed" has many more micro-states than the whole system had when the cream was in the creamer.

One of my favorite papers of all time is "A New Interpretation of Information Rate" by J.L. Kelly (1957). His co-worker Shannon had already used the word "entropy" in conjunction with information-theory, but was rather embarrassed about it. He considered it a metaphor. Kelly showed how information and probability are intricately linked with entropy. Now the information-theoretical definition of entropy is commonly taken to be the definition.

Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln

that really helped me.....

I sincerely did not know that.
the meaning I was taught has been obscured.

The meaning of entropy was just expanded.

Practically speaking, nothing has changed.

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Great stuff!

Interesting concept

It seems like they are talking about an alternate set of energy states. This isn't an area I'm too well versed in, but I do know that mathematically, zero and infinity can behave similarly. I am very interested to see what comes out of this research.

I would caution that, while we are talking about some interesting phenomena, practically working in these conditions is far from a trivial task, and I imagine that a significant amount of energy is expended creating these conditions. Whether usable energy in excess of what is required to generate it can be obtained remains to be seen. I certainly wouldn't expect to see anything practical come out of this anytime soon.

Not alternative

... constrained. The trick is to produce a system which is constrained in some manner that limits the amount of energy it can absorb to some finite amount.

Ĵīɣȩ Ɖåđşŏń

"Fully half the quotations found on the internet are either mis-attributed, or outright fabrications." - Abraham Lincoln

Fair enough

I know just enough about this stuff to be dangerous, barely. It fascinates me greatly, but my strengths are more mathematical.

so to keep their equations right

they will keep the number for absolute zero even though it is wrong. They must work for government.

It's a bit more complicated than that

Heat is, to grossly over-simplify, motion of atoms. They have gone past the point where atomic motion stopped and now motion started in a different way. This is both difficult to categorize and difficult to define. It's way over my head, to be sure. I can say, though, that absolute zero is still absolute zero. It's just that, assuming this experiment is correct, there is a different set of energy states on the other side of absolute zero.