What is Absolute zero: Definition and 129 Discussions

Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvins. The fundamental particles of nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as −273.15 degrees on the Celsius scale (International System of Units), which equals −459.67 degrees on the Fahrenheit scale (United States customary units or Imperial units). The corresponding Kelvin and Rankine temperature scales set their zero points at absolute zero by definition.
It is commonly thought of as the lowest temperature possible, but it is not the lowest enthalpy state possible, because all real substances begin to depart from the ideal gas when cooled as they approach the change of state to liquid, and then to solid; and the sum of the enthalpy of vaporization (gas to liquid) and enthalpy of fusion (liquid to solid) exceeds the ideal gas's change in enthalpy to absolute zero. In the quantum-mechanical description, matter (solid) at absolute zero is in its ground state, the point of lowest internal energy.
The laws of thermodynamics indicate that absolute zero cannot be reached using only thermodynamic means, because the temperature of the substance being cooled approaches the temperature of the cooling agent asymptotically, and a system at absolute zero still possesses quantum mechanical zero-point energy, the energy of its ground state at absolute zero. The kinetic energy of the ground state cannot be removed.
Scientists and technologists routinely achieve temperatures close to absolute zero, where matter exhibits quantum effects such as Bose–Einstein condensate, superconductivity and superfluidity.

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  1. whistle blower

    Absolute Open Mind Holds No Bounds

    I’m male, my nature has always been to question everything explore possibilities, over my latter years convinced that for the short period of time we existed we gained very little, if we did stay around a little longer we may learn a little more, what we cannot prove to be correct is where we...
  2. L

    B What would happen to perception if temperatures almost reached absolute zero?

    Say there was something that made the temperature of the universe almost absolute zero, but around you was a mini bubble where the temperature was normal, and therefore molecules could move normally around you for a small area. How would you perceive the world around you outside of the little...
  3. nomadreid

    I Can Quantum Effects Prevent Reaching Absolute Zero?

    In https://phys.org/news/2016-09-cold-black-holes.html it is stated that a supermassive black hole interior could be 10^-14 degrees Kelvin. Is there a limit, perhaps due to quantum effects, below which a temperature (in a black hole or elsewhere) can go? Or do the possibilities approach 0...
  4. Vectronix

    B Electrons at Absolute Zero -- do they still move?

    Can we all agree that electrons still move at absolute zero?
  5. J

    I Magnetic dipole in vacuum near absolute zero

    Consider a single atom (or particle) in a vacuum (without electric, magnetic or gravitational field) at near zero kelvin (i.e., no photons or particles striking it). I am curious if it will still have a magnetic dipole? If there still is (which I believe), had this been shown experimentally?
  6. E

    B Volume of a solid at absolute zero

    How much does a typical solid shrink when cooled from room temperature to absolute zero. I can't solve this myself because the coefficient of linear thermal expansion varies with temperature
  7. shintashi

    B What is the energy required to approach near absolute zero?

    I'm trying to understand if the amount of effort/energy required to get to absolute zero approaches infinity, or if its a linear thing... is there a point in which dropping near 0 kelvin changes from a 1:1 to an exponential curve? Is the whole thing a curve or is there a static point, like 1...
  8. C

    B Neutron Decay Outside of a Nucleus Near Absolute Zero

    Does neutron decay outside of the nucleus occur faster, slower, or at the same speed when the environment it is in is near absolute zero? Do any external factors affect the speed of a neutron decaying?
  9. A

    Absolute Zero v. The Speed of Light

    Hello, I have a physics question that I am hoping the forum can answer. I have lots of them actually, but I would like to start with the one question and go from there. Ideally the answer to the question should be based upon current accepted physics theory. The Question: How do objects...
  10. S

    Why is there no maximum temperature?

    Given that absolute zero is the lowest temperature possible, were all particles have zero vibration. And given that the speed of light is the highest speed any object, particle, sub atomic or not can travel. Using 2 of the most fundamental laws of physics thermodynamics and general relativity...
  11. F

    How effective is Charles' Law in determining absolute zero?

    Homework Statement Okie so I'm working on my physics work, and I need to compare Charles' Law (for finding absolute zero) to another method used to calculate absolute zero. 3. Attempt at the Solution For this, I was thinking of looking at Carnot engine, but I absolutely do not understand and...
  12. R

    B Does time dilation prove the existence of an absolute zero velocity?

    You may think you've seen this before, since I've seen similar discussions in the archives of this, but I think I've distilled the thoughts down to a couple of facts that contradict the common beliefs regarding relativity. Let me preface this with a basic observation: Lorenz invariance does not...
  13. M

    B Testing spacetime collapse at absolute zero

    The other day I was pondering what happens at/near absolute zero so I did some googling and found articles talking about how it has been demonstrate that as you near absolute zero, the quantum effect start to have an increased range. However, is seems that perhaps the quantum effects only get...
  14. R

    I Heat death of the universe and the 3rd law of thermodynamics

    If the universe keeps expanding and eventually ends in a "big freeze" or heat death, does this contradict the third law of thermodynamics? The third law of thermodynamics states that a crystal at absolute zero has zero entropy. Since the entropy of the universe can never decrease, as the age...
  15. J

    I Fermi gas at the absolute zero T

    I'm currently studying Thermodynamic properties of a Fermi gas at the absolute zero temperature. I get how the internal energy, pressure... etc of the gas are derived. For example, in computing the internal energy, one sums up all the energy of states weighted by its average occupation...
  16. Wrichik Basu

    Do carriers move across a p-n junction at 0 K?

    Often a band diagram is used to explain what happens when two pieces of the same semiconductor, one p-doped, one n-doped, are put together. I am a little confused about it, so here is my question. Initially and at ##0\mathrm{K}##, the surplus carriers should be confined to their respective...
  17. C

    Absolute zero temperature is impossible to achieve?

    Just a general musing. Could absolute zero ever be physically possible or is it like the speed of light but for an inverse reason? The speed of light take infinite energy to achieve. So therefore is impossible because the energy put into the system adds mass. This is not noticeable at slower...
  18. U

    B Brainstorm: Is absolute zero relative

    I know that absolute zero is impossible to achieve but we can get close. According to google the coldest temperature ever reached in a lab was 0.006K. Do you think this is because while the atoms are moving very slow relative to the observer they are still moving at the velocity of Earth's...
  19. Quantum Velocity

    I How can an atom reach less than absolute zero?

    I read a page about making atom under absolute zero. https://www.livescience.com/25959-atoms-colder-than-absolute-zero.html I don't understand very much, if you know pleas help me. Thanks!
  20. i_hate_math

    Second law of thermodynamics and absolute zero

    Does a system with zero entropy represent the thermal equilibrium at some temperature = 0K? Does the second law of thermodynamics entail that the system will eventually evolve to higher entropy? e.g. a system of 7 magnetic dipoles of paramagnetic spin-1/2 particles in an external magnetic...
  21. GregoryC

    B Absolute zero by definition is "nothing"

    Is absolute zero nothing? Can a quanta exist in nothing? There could be no quantum fluctuations at absolute zero.
  22. A

    I Exploring the Connection Between Charles Law and Absolute Zero in Ideal Gases

    Why do all the volume temperature curves of an ideal gas intersect at the same point on the temperature axis ?
  23. P

    Finding Absolute Zero Values from Best Fit Lines with & w/o Uncertainty

    In one of my problems, I have this set of data. I have to create two best fit lines, and find a value of absolute zero for both. The first best fit line is to be made assuming there is NO uncertainty in P. This is rather straightforward, just use the normal linear regression, find a slope...
  24. D

    B Superposition at absolute zero

    I googled a bit about this and managed to find this http://arxiv.org/abs/quant-ph/0505056 http://physics.bu.edu/~mohanty/physica-decoherence.pdf Since I can't make much out of them, maybe except this interesting phrase in the first one "First of all it is intriguing that even at absolute zero...
  25. G

    I Would any physical event happen at absolute zero?

    For example if we could bring a radioactive atom to absolute zero, would it still be subject to the random radioactive decay? Or would absolute zero inhibit the normal half-life decay of the element? Perhaps in other words, would absolute zero inhibit the elapsing of time?
  26. A

    B Why Absolute Zero is Independent of Substance Properties

    Why absolute zero of temperature doesn't depend upon properties of substance?
  27. Octet

    As water depth increases, does temperature go below 0C?

    After passing the thermocline, in which water temperature decreases rapidly over short distances, temperature falls into a sort of constant-looking decline. However, looking at the graph, it looks almost asymptotic. I've not been able to find a chart measuring water depths below 10,000m, so I'm...
  28. Ontophobe

    Four Indistinguishable Phenomena?

    It seems to me, and so I'm really just checking to see if I understand it all correctly, that there are four phenomena in nature that are indistinguishable from one another: (1) crossing beyond an observer's cosmic horizon, (2) crossing the event horizon of a black hole, (3) accelerating toward...
  29. C

    Absolute zero should be impossible

    So since heat comes from atoms vibrating and moving and as they go fast heat increases and when they go slower heat decreases. If I got this right absolute zero is when they give off no heat and this would mean that the atoms are not moving at all. Well then if that is how absolute zero works...
  30. heavystray

    Absolute Zero Gas: Is Motion Possible?

    What happen to gas particles at absolute zero? Is it possible that the particles will still be moving ? Thanks in advance
  31. Nemika

    Can superconductors conduct electricity at absolute zero?

    I've just learned that the conductivity of super conductors increases with decrease in temperature and it becomes infinite at absolute zero. But I thought that all motion ceases at absolute zero. So how can current flow in such conditions? And how can its resistance become zero as some...
  32. Walteholic

    Will absolute zero change with pressure?

    Say we are talking about an ideal gas. According to ideal gas law (PV=nRT), assuming the gas is now at absolute zero, if we further decrease the pressure of the environment, while keeping the container volume constant, will the gas goes under absolute zero? I wasn't an expert in Physics so...
  33. W

    Is it possible to achieve absolute zero?

    Is it possible to achieve absolute zero?
  34. psuedoben

    Do we have any idea what would happen at theoretical absolute zero?

    i have a simple question, but I'm not sure it can be answered with our knowledge of absolute zero: if an object were to exist at absolute zero, that means it has no energy, correct? if that is true, then if you struck something at absolute zero with another object, would the object with no...
  35. T

    How Does Material Choice Impact Physics Experiments on Absolute Zero?

    I just performed a lab in my physics class, and there are a few conceptual questions that I am having trouble with. The lab was simple. We took a constant volume sphere made of Stainless steel and filled with air. We changed the temperature of the water it was into record the corresponding...
  36. N

    The fundamental forces and elementary particles at absolute zero

    We all know that there four fundamental forces in nature, viz. The gravitational force The electromagnetic force The strong nuclear force The weak nuclear force Now also we know that temperature of any system is the average kinetic energy possessed by the particles of the system Now...
  37. E

    An object above absolute zero radiates energy

    An object above absolute zero radiates energy. This implies that object on Earth too radiate energy(infrared?) My question is, if the Earth were not moving, we would be much slower, so would we radiate in some other wavelength of the spectrum? We are essentially traveling really fast because of...
  38. K

    Absolute zero and vibrating atoms

    I am trying to get a better understanding of what it means for an atom to vibrate. Let's say there is a chunk of iron in deep space that starts out with a temperature of 50 degrees celsius and is rapidly losing thermal energy. I will make the following assumptions: 1. The iron has thermal...
  39. SSGD

    Crystal Structure of Metals at Absolute Zero, Waves

    I have been trying to find information on the crystal structure or phase of solid elemental metals at temperatures close to absolute zero, but I can only find information on there ambient structures. Does anyone know of any sources that would have thermodynamic tables for solid metals at low...
  40. PhizKid

    Predicting the temperature of absolute zero experimentally

    Homework Statement A metal ball with pressure gauge at room temperature and standard pressure is immersed into three different liquids each with different temperatures in succession (the three liquids are alcohol in dry ice, boiling water, and freezing water), and then is immersed into these...
  41. K

    Question about Helium at absolute zero

    At absolute zero, I understand that atoms have a minimum vibration (the atoms are not completely still). Because of this minimal vibration, He atoms can not freeze at absolute zero. But if enough pressure is applied, the liquid then becomes a solid. Does the pressure eliminate or reduce the...
  42. J

    What is the reason for absolute zero temperature?

    What is the empiric reason behind the assumption that there is lowest thermodynamic temperature (absolute zero)? And that all other temperatures of bodies in thermodynamic equilibrium are always higher ? I am looking for a reason not using the entropy concept, as the entropy was derived...
  43. C

    Which materials would survive at near absolute zero, intact?

    What would happen to things on Earth if transported to the moon? For instance, say that a house, with furniture and fixtures in place, were dropped gently onto the moon's surface? How about food - meat, vegetables, fruit? Would things crack? Or would they survive the experience so that if...
  44. M

    Can you reach absolute zero in complete empty space

    Ok, so I know that the laws of physics say reaching absolute zero temperature is impossible, but suppose we took a box that was perfectly insulated in completely empy space, and I took all the particles out of it to create a vacuum. Now, since there are no particles in the box, then wouldn't...
  45. B

    Can Understanding Gravity Help Us Grasp Absolute Zero?

    Absolute zero is the theoretical state in which a system reaches 0K, or NO energy present right? And if gravity affects everything with momentum and energy, would it cease to affect absolute zero systems because it includes no energy and thus no momentum? I posted a blog post on it here...
  46. S

    Exploring Beyond Absolute Zero: Thermodynamics Re-examined

    http://www.tgdaily.com/general-sciences-features/68525-beyond-absolute-zero-temperatures-get-hotter#cRgTRdxE2qwYX5DR.16 It's been done in the lab, could this be seen in the cosmos? Could this affect entropies end game? What does this mean for the second law of thermodynamics?
  47. F

    Quantum Gas Below Absolute Zero

    Quantum Gas Below Absolute Zero! http://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.12146 I am a fresh undergraduate student and not expertise in fields. The link above shows an interesting research on negative temperature. I've visited wikipedia and found out that negative...
  48. B

    Exploring Negative Temperatures: What Lies Beyond 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." http://www.livescience.com/25959-atoms-colder-than-absolute-zero.html
  49. N

    Is There Any Motion at Absolute Zero?

    Is it possible for motion to exist at 0 Kelvin?