So you say the absolute zero is the lowest possible temperature, think again...

http://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.12146
http://scitechdaily.com/quantum-gas-temperature-goes-below-absolute-zero/

And here is the picture of it:
http://www.dailytech.com/Researcher...SubAbsolute Zero Quantum Gas/article29557.htm

So, how is this possible can anyone comment this, please and explain what exactly is going on here?
Big thanks.

 

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that is amazing...

um this guy Ulrich Schneider is more bizarre than this discovery...apparently he studies how to thaw frozen embryos >.>

http://www.sciencedirect.com/science/article/pii/0093691X84903078

 

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u should read the comments...

 

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This was already posted here, with some great replies from AlphaNumeric.

 

I would be willing to bet that the amount of degrees below absolute zero that they claim to be acheiving is actually the same as the amount of degrees above absolute zero that they are actually getting. If they calculate the amount of heat in a system from the amount of heat they are transfering out of it than any leak of heat into the system would then show up as a colder temperature. So if they added the heat leaking into the system into the amount of heat coming out of the system then they would just think they have gone below absolute zero when they are just sucking heat of it that is leaking in coming closer to absolute zero. Absolute zero is theoretically impossible because a perfect vacuum is theoretically impossible, there would always be something that could transfer heat into the system! The whole idea of being able to have negative kelvin is ridiculous. How could anyone ever beleive anything they say when they also claim that it would lead to anti-gravity devices! And here I was worried about being to "woo woo" from reading pop physics books, when there is clearly much better "woo woo" on the internet!

 

Well Professor Layman the idea of colder than 0 Kelvin is indeed scientifically correct.

"sub-absolute zero temperature with an ultracold quantum gas that was made up of potassium atoms"

http://www.sciencemag.org/content/339/6115/52

 

One of the reasons given as to why there cannot be a perfect vacuum is because of particle pair production. There would be no way to prevent particle pairs from being created and annihilated inside of a vacuum, so then you could never have a perfect vacuum. They would then add their energy to the system. So then you could never have absolute zero. The vibrations of atoms could never become negative, if it could it would mean that we know nothing about the nature of heat itself. 0 Kelvin would be no movement of the atoms, less than that cannot exist. There cannot be negative vibrations of energy in atoms. They either vibrate or they don't, if it was truely possible to achieve negative kelvin then it would mean that the scale is wrong and has to be adjusted or that we have no idea of why things have heat.

 

I think the reason why it is seen as negative is because of the rate of energy such quantum ultracold gas is able to draw from outside. clearly this could explain the reason for the dark matter paradox of the universe...

 

I see no connection at all whatsoever. The secound link in post #1 refers to dark energy. Dark energy and dark matter are two completely different things. Dark energy is the energy that drives the expansion of the universe and dark matter is the extra force of gravity detected that is not described by General Relativity. I don't see how either have anything to do with being able to report false experimental results on the internet, other than they would just be able to throw that in there too, why not?

 

What they did was more or less redefine temperature.

So what they've done is create a statistical situation where the average works out to be negative.

They have not taken a collection of atoms and removed all kinetic energy from them.

 

I meant "dark energy". Sorry >.<

"Another peculiarity of the sub-absolute-zero gas is that it mimics 'dark energy', the mysterious force that pushes the Universe to expand at an ever-faster rate against the inward pull of gravity. Schneider notes that the attractive atoms in the gas produced by the team also want to collapse inwards, but do not because the negative absolute temperature stabilises them. “It’s interesting that this weird feature pops up in the Universe and also in the lab,” he says. “This may be something that cosmologists should look at more closely.”"

link: http://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.12146

 

No one really knows what the source of dark energy really is, but I think it would be safe to assume that it is not caused by thermodynamical properties. It would be like saying that there is matter outside of the universe. I don't think it would help cosmologists at all. I think it would just make them sound like complete cranks. It wouldn't explain anything, it would be like saying there is just another turtle outside of the universe that makes it expand, and then that stuff is expanded out by another turtle, so on etc. It would just raise more questions than it answers. I don't think any thermodynamical property could even show to give the same distribution of the expansion of the universe that is seen.

 

Has temperture actually been redefined because of this or have they just took it upon themselves to redefine it? How do we know they have done that accurately when they seem to know that dark energy can create anti-gravity?

 

Assuming that particle pair production really exist as well those evidences:
http://xxx.lanl.gov/abs/gr-qc/0308048
http://arxiv.org/abs/quant-ph/0609163

 

And why wouldn't be a matter outside of the universe? We can see with telescopes what we can see, but they all have limitations, we have computer models, but again they have limitations as well, it's not closed story in any way. Basically to really rule out the matter outside the universe you will have to be able to observe everything entire universe like looking at cell under the microscope and look at changes that happens and how it happens and why it happens.

 

Preprint Version

Via arXiv:

• Braun, S. et al. "Negative Absolute Temperature for Motional Degrees of Freedom". arXiv. November 2, 2012. arXiv.org. February 21, 2013. http://arxiv.org/abs/1211.0545​

Note: For some reason, my latest version of Firefox (19.0 Ubuntu canonical 1.0) insisted on opening the PDF via a javascript reader that makes downloading a local copy problematic. I did, however, manage to get a permanent copy with an older version with Safari running in OSX 10.4. The details, naturally, are beyond my comprehension, but I figured it's worth having a copy.

Update: Disregard the prior note; I was being a bonehead and looked right past the Download button on the javascript reader. D'oh!

 

I call that either a statistical gimmick or word-play, not negative temperature.

 

What you think about the "gravity defying phenomena" which is mentioned in the NATURE article.

Perhaps it becomes 'negative mass' at negative Kelvin.

 

It doesn't require a perfect vacuum, the reason it isn't possible is because to 'suck energy out' you need something colder and so to cool to absolute zero you'd need to have something colder. This follows from the first law of thermodynamics, that heat flows from hot to cold objects so the 'sucking' is actually a flow to a colder object, which we do not have.

While it is always important to take such claims with some level of scepticism until details are provided and justifications made it is also unwise to summarily dismiss novel concepts. You of all people should realise that, given the claims you make.

Temperature is something people often think of as 'obvious' as a concept but it is only well defined in the manner people usually think of for systems in equilibrium. For systems out of equilibrium you can get all kinds of weird and wonderful notions. An analogy is the speed of light. All inertial frames will see the speed of light as the same but non-inertial observers can see light do practically anything they like. Or that some wave phenomena can move through certain media faster than light. Or that we can slow down light and even stop it in other media. Too often the layperson version of some scientific principle actually comes with a huge list of caveats and requirements which the layperson will not know about and thus do not realise their notion of various physical principles are not universal. The canonical example is how often hacks trot out \(E=mc^{2}\) like it is universally true.

 

Right so if you put a thermometer up to something that is supposed to be 0 kelvin then it will transfer the heat from the thermometer that is then hotter.

Beleive it or not, I always approuch everything with complete scepticism. I think I see now why people where saying that we don't know what temperature is, and it is not really the vibration of atoms. I was told this in school, and I read this from the internet. My good sense tells me that I shouldn't beleive the internet and go with what I learned in school. It then goes against everything I have learned so far in more ways than one. The title of thread even goes to show this, everyone is taught that absolute zero is the coldest temperature that cannot be reached, but then it goes on to say that it can be negative. Anyone that remembers anything they learned about temperature in gradeschool should then know that this cannot be correct.

They post it up on posters and billboards as though it is universal. I am so hardcore with the notion of the speed of light, that I wouldn't beleive any of these things you mentioned about it either. I would never indulge myself into thinking that the photons actually started going a slower speed in any situation. I beleive the constant speed of light is universal, and I was taught in my physics course that the speed of light does not actually change in a medium. I wonder if science even knows anything about particles traveling through a medium regarding speed or direction. I think it is something that needs to be looked at further with a close microscope and an eye of scrutiny.