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Quantum gas goes below absolute zero - Ultracold atoms pave way for negative-Kelvin materials.
Nature News ^ | 03 January 2013 | Zeeya Merali

Posted on 01/03/2013 11:44:46 PM PST by neverdem

It may sound less likely than hell freezing over, but physicists have created an atomic gas with a sub-absolute-zero temperature for the first time1. Their technique opens the door to generating negative-Kelvin materials and new quantum devices, and it could even help to solve a cosmological mystery.

Lord Kelvin defined the absolute temperature scale in the mid-1800s in such a way that nothing could be colder than absolute zero. Physicists later realized that the absolute temperature of a gas is related to the average energy of its particles. Absolute zero corresponds to the theoretical state in which particles have no energy at all, and higher temperatures correspond to higher average energies.

However, by the 1950s, physicists working with more exotic systems began to realise that this isn't always true: Technically, you read off the temperature of a system from a graph that plots the probabilities of its particles being found with certain energies. Normally, most particles have average or near-average energies, with only a few particles zipping around at higher energies. In theory, if the situation is reversed, with more particles having higher, rather than lower, energies, the plot would flip over and the sign of the temperature would change from a positive to a negative absolute temperature, explains Ulrich Schneider, a physicist at the Ludwig Maximilian University in Munich, Germany.

Peaks and valleys

Schneider and his colleagues reached such sub-absolute-zero temperatures with an ultracold quantum gas made up of potassium atoms. Using lasers and magnetic fields, they kept the individual atoms in a lattice arrangement. At positive temperatures, the atoms repel, making the configuration stable. The team then quickly adjusted the magnetic fields, causing the atoms to attract rather than repel each other. “This suddenly shifts the atoms from their most stable, lowest-energy state to the highest possible energy...”...

(Excerpt) Read more at nature.com ...


TOPICS: Culture/Society; News/Current Events; Technical; Testing
KEYWORDS: absolutezero; physics; stringtheory

1 posted on 01/03/2013 11:45:03 PM PST by neverdem
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To: neverdem

bfl


2 posted on 01/04/2013 12:03:42 AM PST by BerryDingle (I know how to deal with communists, I still wear their scars on my back from Hollywood-Ronald Reagan)
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To: neverdem

Does this mean absolute zero is lower, is all, or what?


3 posted on 01/04/2013 12:24:33 AM PST by Tublecane
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To: neverdem
If the wind chill factor got to absolute zero would all molecular activity stop or would it just feel like it did?
4 posted on 01/04/2013 12:31:03 AM PST by Hillarys Gate Cult (Liberals make unrealistic demands on reality and reality doesn't oblige them.)
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To: Tublecane
Not really.

It's a technicality that isn't new. There are certain systems with anomolous "temperatures" because the thermodynamic definition of temperature isn't quite perfectly defined. It's a macroscopic state variable that doesn't completely line up with the microscopic description of reality (and it isn't supposed to, by the way.)

Simplest example I learned in graduate school was: Under the thermodynamic defintion of temperature, a perfect vacuum is at absolute zero because it can provide no heat to any themral reservoir placed in contact with it, no matter how cold. Thus, a vacuum must be "colder" than anything. But at the same time, it must also be at inifinte temperature, because no thermal reservoir, no matter how hot, placed in contact with it can transfer heat to it. So it has to be hotter than anything else. There are a number of these kinds of anomalies.

5 posted on 01/04/2013 12:44:15 AM PST by FredZarguna (Funded by Arab oil money, so you know it's objective and altruistic.)
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To: Hillarys Gate Cult
The article is mistaken.

The absolute zero of temperature is only a point of zero energy in classical physics, which is only an approximation of reality.

In quantum physics it is the point of lowest system energy, which is never zero.

[The simplest, but not always the most correct way to see this is that by the Uncertainty Principle, the ground state of every quantum system that has finite spatial extent (which, for example, descibes anything in our universe) has some non-zero momentum. So "all" motion cannot cease, even at absolute zero.]

6 posted on 01/04/2013 12:51:04 AM PST by FredZarguna (Funded by Arab oil money, so you know it's objective and altruistic.)
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To: FredZarguna

They date absolute zero vaguely to the mid-nineteenth century. I don’t think Kelvin lived very far into the last century. It had occurred to me absolute zero predates Einstein and quantum mechanics. I wish they would come out and tell us whether various oldtimey concepts are real, or merely being used to help us rubes follow along.

Or maybe they don’t know, either.


7 posted on 01/04/2013 1:03:27 AM PST by Tublecane
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To: neverdem

The really important question is: How can I use this information in MY life?


8 posted on 01/04/2013 2:04:01 AM PST by count-your-change (You don't have to be brilliant, not being stupid is enough.)
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To: neverdem

I guess this means cryo-freeze like in “Demolition Man” is possible?

We could have cold bombs or cryo grenades?

I can get motivated knowing I have access to a cryo grenade that will stop molecular function of metals to the point I could shoot a 9mm at a tank and it will shatter like fine crystal.


9 posted on 01/04/2013 3:02:13 AM PST by Eye of Unk (A Civil Cold War in America is here, its already been declared.)
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To: neverdem

It appears to be that the good scientists merely redefined Absolute Zero to include some atomic motion thus permitting them to say that they can thus bring a gas to a state of less than Absolute Zero. One can also redefine the pure color Red to include some yellow and thus surprisingly find a state of red that includes some yellow.


10 posted on 01/04/2013 4:29:13 AM PST by arthurus (Read Hazlitt's Economics In One Lesson ONLINE www.fee.org/library/books/economics-in-one-lesson)
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To: neverdem

But, but science taught us that absolute...that is ABSOLUTE zero is the coldest anything can get! Science is based on facts and logic and HAVE to be right!!! This article must be a religious propaganda piece!


11 posted on 01/04/2013 5:01:36 AM PST by Wpin ("I Have Sworn Upon the Altar of God eternal hostility against every form of tyranny...")
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To: Tublecane
"Does this mean absolute zero is lower, is all, or what?"

Absolutely relative. Everything is absolutely relative. Except the Bible, which is absolute.

12 posted on 01/04/2013 5:12:33 AM PST by Psalm 73 ("Gentlemen, you can't fight in here - this is the War Room".)
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To: Tublecane
It means nothing is absolute at all. Everything is an illusion.
13 posted on 01/04/2013 5:30:40 AM PST by mosaicwolf (Strength and Honor)
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To: Tublecane
I wish they would come out and tell us whether various oldtimey concepts are real, or merely being used to help us rubes follow along.

All of science is models of reality. All models break down at some point.

14 posted on 01/04/2013 5:48:03 AM PST by SoothingDave
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To: FredZarguna

How do you contact a vacuum? There’s nothing to contact.


15 posted on 01/04/2013 7:01:31 AM PST by super7man
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To: count-your-change
How can I use this information in MY life?

Exactly, how do you get a Pinto out of this?

16 posted on 01/04/2013 7:04:04 AM PST by super7man
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To: FredZarguna

That’s a very interesting way of looking at the properties of a vacuum. Thanks. Haven’t we also come to the conclusion that the ‘ether’ as spoken of in previous centuries may actually be more “real” than we were told through most of the 20th century, as there are quantum fluctuations of space-time that seem to have some rather interesting and peculiar properties.


17 posted on 01/04/2013 7:13:28 AM PST by zeugma (Those of us who work for a living are outnumbered by those who vote for a living.)
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To: neverdem
If you have sub absolute zero temperatures, then maybe that wasn't absolute zero. At the other end, they're getting faster than the speed of light, which was the absolute speed limit.

Science is going to have to undergo a paradigm shift.

18 posted on 01/04/2013 7:25:28 AM PST by Jabba the Nutt (.Are they stupid, malicious or evil?)
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To: neverdem

Mass that exists devoid of energy?

A state yet beyond the complete absence of heat?


19 posted on 01/04/2013 9:33:14 AM PST by conserv8 (It's not the end, it's the beginning.)
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To: Tublecane
The Thermodynamic state variable called temperature is well defined and has an absolute minimum, which we may assign to zero. The science of this is not controversial, and has not changed.

The exact value of this absolute zero, relative to Celsius temperature has been measured to within a few microkelvins (it is actually defined as 0K, which is defined to be -273.15 C) It was well established IIRC in the late 19th century by extrapolation. It actually cannot be reached (this is one of several alternative versions of what is called The Third Law of Thermodynamics: "By no finite series of processes is the absolute zero of temperature achievable.") In its strongest formulation, the absolute zero of temperature isn't really defined in terms of temperature, it's defined as the temperature at which the entropy of a perfect crystal is zero.

A much better discussion of what is going on here than is stated in the article is in http://en.wikipedia.org/wiki/Absolute_zero in the section under "negative temperature." It is brief and accessible to the layman.

The beauty of the macroscopic state variables of thermodynamics is that they don't depend on any underlying theory of matter: none of the theorems or results of classical thermodynamics were changed when classical physics was modified by relativity, and none of them were changed with the advent of quantum mechanics. If quantum mechanics was overthrown tomorrow, macroscopic thermodynamics would still be entirely valid and not a single definition, result, or equation would change.

20 posted on 01/04/2013 10:37:20 AM PST by FredZarguna (Funded by Arab oil money, so you know it's objective and altruistic.)
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To: neverdem

Bookmark.


21 posted on 01/04/2013 10:39:45 AM PST by The Cajun (Sarah Palin, Mark Levin......Nuff said.)
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To: super7man
Create the vacuum in a closed system, and bring the walls of that system into contact with a thermal reservoir. The zeroth law of thermodynamics then allows you to discuss their relative temperatures.
22 posted on 01/04/2013 10:42:28 AM PST by FredZarguna (Funded by Arab oil money, so you know it's objective and altruistic.)
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To: zeugma

“the ‘ether’ as spoken of in previous centuries may actually be more ‘real’ than we were told”

I thought that’s what bosons and fermions were, or else I have no idea. Not that we’re sure they even exist.


23 posted on 01/04/2013 10:48:21 AM PST by Tublecane
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To: neverdem

ping


24 posted on 01/04/2013 10:49:35 AM PST by BrandtMichaels
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To: zeugma
Einstein himself did not give up completely on the idea of the aether, because without it empty space needs to have properties which he found unappealing. Most physicist didn't share these qualms, and actually sided with Newton's idea that acceleration was defined as motion with respect to something he (Newton) called "absolute space." Those concepts have, even with the advent of General Relativity, held.

Recently, the Higgs Field (if it exists... some are skeptical) appears to have some of the properties hitherto assigned to "the Luminiferous Aether."

25 posted on 01/04/2013 10:52:16 AM PST by FredZarguna (Funded by Arab oil money, so you know it's objective and altruistic.)
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To: 6SJ7; AdmSmith; AFPhys; Arkinsaw; allmost; aristotleman; autumnraine; Beowulf; Bones75; BroJoeK; ...

Thanks neverdem.
...physicists have created an atomic gas with a sub-absolute-zero temperature for the first time...
And when the gullible grad student got his tongue stuck on it, everyone else laughed.

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26 posted on 01/04/2013 9:07:34 PM PST by SunkenCiv (Romney would have been worse, if you're a dumb ass.)
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To: FredZarguna
You've just answered the riddle posed by "The 2,000 Year Old Man" ...

Q. What is the greatest invention in history?

A. The Thermos.

Q. The Thermos? Why?

A. It keeps hot foods hot, it keeps cold foods cold.

Q. And why is that so important?

A. How does it know?

Cheers!

27 posted on 01/05/2013 6:03:38 AM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
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To: FredZarguna

Non-commutation of position and momentum operators.


28 posted on 01/05/2013 6:08:15 AM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
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To: FredZarguna
The beauty of the macroscopic state variables of thermodynamics is that they don't depend on any underlying theory of matter: none of the theorems or results of classical thermodynamics were changed when classical physics was modified by relativity, and none of them were changed with the advent of quantum mechanics. If quantum mechanics was overthrown tomorrow, macroscopic thermodynamics would still be entirely valid and not a single definition, result, or equation would change.

What's frightening is how well they agree over how wide a range of conditions.

The odds of that must be around 1720, due to the 2nd Law of Thermal Documents /crevo-thread>

Cheers!

29 posted on 01/05/2013 6:11:11 AM PST by grey_whiskers (The opinions are solely those of the author and are subject to change without notice.)
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To: count-your-change

“The really important question is: How can I use this information in MY life?”

—<>-—<>-—<>-—<>-—<>-—

I don’t really believe you think the only reason for the universe to exist is all about you. That said, while we may not yet know how to make use of this information, we didn’t know in the 1920’s that quantuum mechanics would make possible the iPhone, etc., and in that respect all this type of information is important to learn as much as we can.


30 posted on 01/05/2013 9:08:56 AM PST by AFPhys ((Praying for our troops, our citizens, that the Bible and Freedom become basis of the US law again))
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To: FredZarguna

You have done a very good job of making this rather mis-named concept of “negative temperature” accessible to people here. Thanks.


31 posted on 01/05/2013 9:11:12 AM PST by AFPhys ((Praying for our troops, our citizens, that the Bible and Freedom become basis of the US law again))
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To: AFPhys
I hate being wrong but I was just certain there was a bit humor in the comment. Maybe a tad of sarcasm too.
32 posted on 01/05/2013 10:24:11 AM PST by count-your-change (You don't have to be brilliant, not being stupid is enough.)
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To: grey_whiskers
I miss those crevo threads ... sometimes. So many people with no idea what the Bible actually says arguing with so many people who don't understand science. A perfect collision of ignorance. I forgot about that 1720 and the other thing. Classic.
33 posted on 01/05/2013 11:40:57 AM PST by FredZarguna (The fundamental question is: how is stopping people from destroying themselves part of governance?)
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To: Hillarys Gate Cult

If Helen Keller fell down in the woods and no one was around to hear it, would she make a sound?


34 posted on 01/05/2013 11:44:00 AM PST by Hoodat ("As for God, His way is perfect" - Psalm 18:30)
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To: Tublecane
The aether was a medium that nineteenth and very early twentieth century physicists believed was necessary to allow the propagation of light. Prior to that, all known methods of conveying waves from one point to another (water, sound) required something through which they moved.

The luminiferous aether was problematic from the beginning, because it had to have bizarre physical properties. For example, as a general rule, the more rigid a material is, the faster it transmits waves. The speed of sound in air is only about 330 meters/sec at sea level, but it is over 6000 meters per second through steel (and more than twice that through diamond.) So, the aether had to be tremendously rigid, since the speed of light through the supposed aether was 50,000 times faster than the speed of sound through steel.

Despite that requirement, it had to offer no mechanical "drag" through space, because the motions of the planets (for example) were perfectly accounted for by Newton's Laws, which assumed that space was effectively empty.

The natural question then arose: does the speed of light change as the earth moves around the sun? It should, because for one part of the year light transmitted through the aether should be moving with the aether, and for the other half of the year, it should be moving against the aether. In fact, because the earth travels in roughly circular motion around the sun, the speed of light should rise and fall sinusoidally as the earth moves through the aether. In a series of brilliant experiments, two American Physicists, Albert Michelson and Edward Morley, proved that the speed of light never changed, regardless of the orientation of the observer or location of the Earth. It is one of the most famous negative results in history, and spelled the eventual end of the theory of the "luminiferous aether."

Fermions and bosons don't have anything to do with this really. In quantum mechanics, there is a requirement that the wave functions of systems of particles must be either symmetric or antisymmetric when the particles trade places. This must happen because the sum total of the square of the wave function indicates the likelihood of finding a particle somewhere in space, and that squared value must not change when two particles are "swapped." [They still have to be somewhere, even if they trade places!]So, the wave function can only change by a factor of +1 (symmetric) or -1 (antisymmetric) when the particles are interchanged. [AND ... Those are the only possibilities, because -1 and +1 are the only numbers that square to 1.]

Particles which make up systems with antisymmetric wave functions are called fermions. (Named after the Italian/American Physicist, Enrico Fermi; probably the most underrated physicist of the twentieth century: both a brilliant theoretician and equally fantastic experimentalist -- a very rare combination in the last 200 years.) Very loosely, a fermion is any material particle: electrons, protons, neutrons, quarks, ... and their antiparticles.

Particles which make up systems with symmetric wave functions are called bosons (Named for Satyendra Nath Bose and Albert Einstein, who developed some of their statistical properties.) Again very loosely, particles which are either: 1) even number combinations of more basic particles or, more famously, 2) the so-called "gauge bosons" which transmit forces throughout the universe are bosons. Gravitons, gluons, photons, the W and Z particles, and the Higgs boson are all bosons. So is, for example, Helium 4 (because it's made up of an even number of fermions: 2 protons, and 2 neutrons.) But not Helium 3, because it's made up of an odd number of fermions (3 in all, 2 protons, and 1 neutron.)

So ... clearly fermions and bosons exist.

And despite the silly claims of science "journalists" and popularizers that quantum physics "describes things that are very small," the truth is that whether a system is made up of bosons or fermions has a great deal to say about its large-scale behavior. For example, nearly ALL of the properties of metals are attributable to the fact that their free electrons are fermions. (Fermi himself developed this theory.) The behavior of many elements near absolute zero changes dramatically, depending on whether their isotopes are bosons (like He4) or fermions (like He3.)

This universe could not possibly exist in any kind of recognizable form if the photon were not a boson.

35 posted on 01/05/2013 12:25:37 PM PST by FredZarguna (The fundamental question is: how is stopping people from destroying themselves part of governance?)
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To: AFPhys

You’re welcome. I miss teaching, which shows sometimes. Maybe when I retire I’ll return to it as a second career.


36 posted on 01/05/2013 12:27:21 PM PST by FredZarguna (The fundamental question is: how is stopping people from destroying themselves part of governance?)
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To: FredZarguna

The way I had the existence of one particular type, the Higgs boson, was that in order to unite various particles under the Standard Model they had to posit the existence of clouds of bosons, so to speak, interacting with electrons to give them their mass. Apparently such things come into being through spontaneous symmetry breaking, and I don’t think I’ll ever really understand what that is.

Why I brought it up is that imagining electrons passing through as yet undetected particles to explain their behavior reminded me of what I had learned about the ether through the Michelson-Morely experiment. No doubt the ether theory was much grander and more complex than that. I often misuse scientific concepts. But scientists are always borrowing for their own purposes half remembered bits from the humanities, so it’s a wash.


37 posted on 01/05/2013 12:50:41 PM PST by Tublecane
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