Category Archives: Thermodynamics

Maxwell’s Demon and Its Fallacies Demystified

Milivoje M. Kostic
A demonic being, introduced by Maxwell, to miraculously create thermal non-equilibrium and violate the Second law of thermodynamics, has been among the most intriguing and elusive wishful concepts for over 150 years. Maxwell and his followers focused on ‘effortless gating’ a molecule at a time, but overlooked simultaneous interference of other chaotic molecules, while the demon exorcists tried to justify impossible processes with misplaced ‘compensations’ by work of measurements and gate operation, and information storage and memory erasure with entropy generation. The illusive and persistent Maxwell’s demon fallacies by its advocates, as well as its exorcists, are scrutinized and resolved here. Based on holistic, phenomenological reasoning, it is deduced here that a Maxwell’s demon operation, against natural forces and without due work effort to suppress interference of competing thermal particles while one is selectively gated, is not possible at any scale, since it would be against the physics of the chaotic thermal motion, the latter without consistent molecular directional preference for selective timing to be possible. Maxwell’s demon would have miraculous useful effects, but also some catastrophic consequences.

Read more at https://arxiv.org/ftp/arxiv/papers/2001/2001.10083.pdf

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Analogy between thermal emission of nano objects and Hawking’s radiation

cavity
Karl Joulain
We analyze in this work some analogies between thermal emission of nano objects and Hawking’s radiation. We first focus on the famous expression of the black hole radiating temperature derived by Hawking in 1974 and consider the case of thermal emission of a small aperture made into a cavity (Ideal Blackbody). We show that an expression very similar to Hawking’s temperature determines a temperature below which an aperture in a cavity cannot be considered as standard blackbody radiating like T^4. Hawking’s radiation therefore appear as a radiation at a typical wavelength which is of the size of the horizon radius. In a second part, we make the analogy between the emission of particle-anti particle pairs near the black hole horizon and the scattering and coupling of thermally populated evanescent waves by a nano objects. We show here again that a temperature similar to the Hawking temperature determines the regimes where the scattering occur or where it is negligible.
Read more at https://arxiv.org/pdf/1808.08037.pdf

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Aside

Do we know what the temperature is?

Jiri J. Mares
Temperature, the central concept of thermal physics, is one of the most frequently employed physical quantities in common practice. Even though the operative methods of the temperature measurement are described in detail in various practical instructions and textbooks, the rigorous treatment of this concept is almost lacking in the current literature. As a result, the answer to a simple question of “what the temperature is” is by no means trivial and unambiguous. There is especially an appreciable gap between the temperature as introduced in the frame of statistical theory and the only experimentally observable quantity related to this concept, phenomenological temperature. Just the logical and epistemological analysis of the present concept of phenomenological temperature is the kernel of the contribution.
Read more at https://arxiv.org/ftp/arxiv/papers/1604/1604.05563.pdf

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