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 quantum 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 quantum information theory. 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 absolute zero (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 heat capacity, 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 thermodynamics 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.
(Phys.org)—Over the past several years, physicists have developed quantum shortcuts that speed up the operation of quantum systems. Surprisingly, some of these shortcuts theoretically appear to enable systems to operate ...
The likelihood of seeing quantum systems violating the second law of thermodynamics has been calculated by UCL scientists.
In the 1800s scientists studying things like heat and the behavior of low density gases developed a theory known as thermodynamics. As the name suggests, this theory describes the dynamic behavior of heat (or more generally ...
(Phys.org) —The laws of thermodynamics determine what is possible and impossible in classical systems. Lately, scientists have been working on establishing quantum analogues of these fundamental laws to determine the performance ...
According to the basic laws of thermodynamics, if you leave a warm apple pie in a winter window eventually the pie would cool down to the same temperature as the surrounding air.
(Phys.org)—A few years ago, physicists showed that it's possible to erase information without using any energy, in contrast to the assumption at the time that erasing information must require energy. Instead, the scientists ...
(Phys.org)—A team of researchers at Universite Paris-Diderot has uncovered the reason for wobbling of wheeled suitcases. In their paper published in Proceedings of the Royal Society A, the group explains the physics behind ...
There is a great deal of excitement around virtual reality (VR) headsets that display a computer-simulated world and augmented reality (AR) glasses that overlay computer-generated elements with the real world. Although AR ...
Fusion power has the potential to provide clean and safe energy that is free from carbon dioxide emissions. However, imitating the solar energy process is a difficult task to achieve. Two young plasma physicists at Chalmers ...
Researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and Argonne National Laboratory have collaborated to design, build and test two devices that utilize different superconducting ...
Biomedical researchers are understanding the functions of molecules within the body's cells in ever greater detail by increasing the resolution of their microscopes. However, what's lagging behind is their ability to simultaneously ...
Measurements at the Australian Centre for Neutron Scattering have helped clarify the arrangement of magnetic vortices, known as skyrmions, in manganese silicide (MnSi).
© Phys.org 2003 - 2017, Science X network
Source
