Left: just before the appearance of a Bose–Einstein condensate. Velocity-distribution data of a gas of rubidium atoms at a temperature within a few billionths of a degree above absolute zero. This explains the failure of the classical equipartition theorem for metals that eluded classical physicists in the late 19th century. For temperatures significantly below the Fermi temperature, the electrons behave in almost the same way as at absolute zero. The Fermi temperature is defined as this maximum energy divided by the Boltzmann constant, and is on the order of 80,000 K for typical electron densities found in metals. The maximum energy that electrons can have at absolute zero is called the Fermi energy. The electrons, being fermions, must be in different quantum states, which leads the electrons to get very high typical velocities, even at absolute zero. One model that estimates the properties of an electron gas at absolute zero in metals is the Fermi gas. This ensures that Δ G and Δ H are nearly the same over a considerable range of temperatures and justifies the approximate empirical Principle of Thomsen and Berthelot, which states that the equilibrium state to which a system proceeds is the one that evolves the greatest amount of heat, i.e., an actual process is the most exothermic one. Moreover, the slopes of the derivatives of Δ G and Δ H converge and are equal to zero at T = 0. However, this is not required endothermic reactions can proceed spontaneously if the TΔ S term is large enough. If Δ S and/or T are small, the condition Δ G < 0 may imply that Δ H < 0, which would indicate an exothermic reaction. Experimentally, it is found that all spontaneous processes (including chemical reactions) result in a decrease in G as they proceed toward equilibrium. Thus, as T decreases, Δ G and Δ H approach each other (so long as Δ S is bounded). The original Nernst heat theorem makes the weaker and less controversial claim that the entropy change for any isothermal process approaches zero as T → 0: Max Planck's strong form of the third law of thermodynamics states the entropy of a perfect crystal vanishes at absolute zero. In such a circumstance, pure substances can (ideally) form perfect crystals with no structural imperfections as T → 0. Thermodynamics near absolute zero Īt temperatures near 0 K (−273.15 ☌ −459.67 ☏), nearly all molecular motion ceases and Δ S = 0 for any adiabatic process, where S is the entropy. 2 Relation with Bose–Einstein condensate.Scientists and technologists routinely achieve temperatures close to absolute zero, where matter exhibits quantum effects such as Bose–Einstein condensate, superconductivity and superfluidity. The kinetic energy of the ground state cannot be removed. 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. In the quantum-mechanical description, matter (solid) at absolute zero is in its ground state, the point of lowest internal energy. 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. The corresponding Kelvin and Rankine temperature scales set their zero points at absolute zero by definition. 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 fundamental particles of nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.Zero kelvin (−273.15 ☌) is defined as absolute zero.Ībsolute 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 kelvin. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file.
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