Physicists prove that it's impossible to cool an object to absolute zero

March 23, 2017 by Lisa Zyga, Phys.org feature

Credit: photos-public-domain.com
(Phys.org)—In 1912, chemist Walther Nernst proposed that cooling an object to absolute zero is impossible with a finite amount of time and resources. Today this idea, called the unattainability principle, is the most widely accepted version of the third law of thermodynamics—yet so far it has not been proved from first principles.

Now for the first time, physicists Lluís Masanes and Jonathan Oppenheim at the University College of London have derived the third law of thermodynamics from first principles. After more than 100 years, the result finally puts the third law on the same footing as the first and second laws of thermodynamics, both of which have already been proved.

"The goal of fundamental physics is to derive all the laws of nature and to describe all phenomena by only assuming a small set of principles (like mechanics, the Standard Model of particle physics, etc.)," Masanes told Phys.org. "And that's what we do. In addition, this derivation unveils the strong connections among the limitations of cooling, the positivity of the heat capacity, the reversibility of microscopic dynamics, etc. Personally, I love that the whole of thermodynamics (including the third law) has been derived from more fundamental principles."

To prove the third law, the physicists used ideas from computer science and . There, a common problem is to determine the amount of resources required to perform a certain task. When applied to cooling, the question becomes how much work must be done and how large must the cooling reservoir be in order to cool an object to (0 Kelvin, -273.15°C, or -459.67°F)?

The physicists showed that cooling a system to absolute zero requires either an infinite amount of work or an infinite reservoir. This finding is in agreement with the widely accepted physical explanation of the unattainability of absolute zero: As the temperature approaches zero, the system's entropy (disorder) approaches zero, and it is not possible to prepare a system in a state of zero entropy in a finite number of steps.

The new result led the physicists to a second question: If we can't reach absolute zero, then how close can we get (with finite time and resources)? It turns out that the answer is closer than might be expected. The scientists showed that lower temperatures can be obtained with only a modest increase of resources. Yet they also showed that there are limits here, as well. For example, a system cannot be cooled exponentially quickly, since this would result in a negative , which is a physical impossibility.

One of the nice features of the new proof is that it applies not only to large, classical systems (which traditional usually deals with), but also to quantum systems and to any conceivable type of cooling process.

For this reason, the results have widespread theoretical implications. Cooling to very low temperatures is a key component in many technologies, such as quantum computers, quantum simulations, and high-precision measurements. Understanding what it takes to get close to absolute zero could help guide the development and optimization of future cooling protocols for these applications.

"Now that we have a better understanding of the limitations of cooling, I would like to optimize the existing methods or come up with new ones," Masanes said.

Explore further: Quantum shortcuts cannot bypass the laws of thermodynamics

More information: Lluís Masanes and Jonathan Oppenheim. "A general derivation and quantification of the third law of thermodynamics." Nature Communications. DOI: 10.1038/ncomms14538

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21 comments

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JongDan
3 / 5 (7) Mar 23, 2017
Bad wording – you cannot "prove" something in real world by looking at mathematical models of reality. It does express the 3rd Law of TD in more basic terms though.
gkam
1 / 5 (6) Mar 23, 2017
If they think there is no such achievement as absolute zero they have never looked into the eyes of my Air Force Hematologist.

He was a monster.
Uncle Ira
2.8 / 5 (9) Mar 23, 2017
If they think there is no such achievement as absolute zero they have never looked into the eyes of my Air Force Hematologist.
Cher, why you don't read the articles before you make the comment? This is not about the Air Force or hematologists. It's about physics.

He was a monster.
There is not anything about monsters in him either.
RoyPr
3 / 5 (2) Mar 23, 2017
"Prove?" How about: "Showing consistency with more fundamental principles"?
Bongstar420
2.6 / 5 (5) Mar 23, 2017
Perpetual motion.

Violation of thermodynamics? Where does that energy come from? I mean really. They are saying its impossible to remove the energy from substance 100%....which means if you extract energy from it, it must be perpetually resupplied from somewhere.
Dingbone
Mar 23, 2017
This comment has been removed by a moderator.
NoStrings
3.7 / 5 (3) Mar 23, 2017
No shit Einstein? Just thinking a bit ahead of time would save you time you wasted making a fool of yourself.
1. You would need a reference frame at absolute zero, doesn't exist!
2. Quantum fluctuations introduce minuscule disturbances, and plus Heisenberg principle.
TechnoCreed
3.7 / 5 (6) Mar 23, 2017
1. You would need a reference frame at absolute zero, doesn't exist!
Yes it does: a quantum object that would have zero kinetic energy would be at 0 Kelvin.
Pooua
3.7 / 5 (3) Mar 23, 2017
They are saying its impossible to remove the energy from substance 100%....which means if you extract energy from it, it must be perpetually resupplied from somewhere.


My gut reaction is to suppose that the process of attempting to extract energy would add energy, like trying to get the last bit of spread using the same spoon reaches a limit. My understanding of the article, though, is that cooling is an exponential process, with the reference substance setting an asymptote that would require infinite time to reach.
Pooua
4 / 5 (4) Mar 23, 2017
Does it mean the disproof or confirmation the existence of absolute zero temperature?


Absolute zero temperature is a concept. This proof says that the concept can never be realized.
NoStrings
1 / 5 (1) Mar 24, 2017
TechnoCreed, are you stupid? Remember uncertainty principle? There is nothing that doesn't possess at least h/2 proportional uncertainty of momentum, or kinetic energy relative to anything else you can imagine. For sure, it applies to any two arbitrary objects. Why is it so hard for idiots to comprehend even the basics?
Ojorf
3 / 5 (6) Mar 24, 2017
Gee people, the article is about the 3rd law. Everyone new about it, everyone knew it was a 'law', everyone had an idea for which reasons it was impossible to reach 0K. It just hasn't been proven from first principles, now it has.
Thats excellent!
Ojorf
3 / 5 (6) Mar 24, 2017
Bad wording – you cannot "prove" something in real world by looking at mathematical models of reality.


You must admit It is just weird how the world does seem to adhere strictly (as far as we can tell and test) to mathematical rules, we just cannot catch it breaking any. And whenever it seems to, it was due to our error or lack of understanding.
bazooka bob
5 / 5 (1) Mar 24, 2017
Is there an upper limit to temperature?
Da Schneib
5 / 5 (3) Mar 24, 2017
Nice to find a rigorous proof of this. The lack of such a proof has formerly relegated the 3LOT to lesser status than the first two; now it's on equal footing.
Da Schneib
5 / 5 (1) Mar 24, 2017
@bazooka not as far as we've been able to figure. Depends on what you mean by "temperature" though. It's probably more meaningful at the high end to talk about the average kinetic energy of a particle in the system than a derived quantity like temperature.
Kron
5 / 5 (3) Mar 24, 2017
@bazooka bob,
1.417x10^32 K is Planck temperature. At this temperature the radiation that a body would emit would have a wavelength of 1.616x10^-35 meters (which is a Planck length). At this temperature our theories break down as any higher temperature would have the body emitting radiation with a wavelength shorter than a Planck length. Barring a theory of quantum gravity, in theory at least, 1.417x10^32 K is the upper bound limit to temperature.
Hyperfuzzy
5 / 5 (2) Mar 25, 2017
Obvious, zero flux does not exist!
Whydening Gyre
not rated yet Mar 25, 2017
Obvious, zero flux does not exist!

BINGO!!!
milliondollarbill
not rated yet Mar 26, 2017
2.5 thousandths of a degree above absolute zero
Whydening Gyre
5 / 5 (1) Mar 26, 2017
IF the dynamic actions of this single atom could be measured, then it might be possible to control the trapping field such that the atom does not move at all. The ultimate problem is that "zero", like "infinity" are hard to prove. Is this significant? Probably not.

Zero is just the opposite of infinity. Both unattainable...

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