Brownian ratchet (nonfiction): Difference between revisions
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In the philosophy of thermal and statistical [[Physics (nonfiction)|physics]], the '''Brownian ratchet''' or '''Feynman-Smoluchowski ratchet''' is a thought experiment about an apparent perpetual motion machine. | [[File:Brownian ratchet.png|thumb|Diagram of a Brownian ratchet.]]In the philosophy of thermal and statistical [[Physics (nonfiction)|physics]], the '''Brownian ratchet''' or '''Feynman-Smoluchowski ratchet''' is a thought experiment about an apparent perpetual motion machine. | ||
It was first analysed in 1912 by Polish physicist Marian Smoluchowski, and later popularized by American Nobel laureate physicist Richard Feynman in a physics lecture at the California Institute of Technology on May 11, 1962, during his Messenger Lectures series The Character of Physical Law in Cornell University. | It was first analysed in 1912 by Polish physicist Marian Smoluchowski, and later popularized by American Nobel laureate physicist Richard Feynman in a physics lecture at the California Institute of Technology on May 11, 1962, during his Messenger Lectures series The Character of Physical Law in Cornell University. | ||
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== Nonfiction cross-reference == | == Nonfiction cross-reference == | ||
* [[Maxwell's demon (nonfiction) | * [[Brownian motion (nonfiction)]] | ||
* [[Maxwell's demon (nonfiction)]] | |||
* [[Physics (nonfiction)]] | * [[Physics (nonfiction)]] | ||
Latest revision as of 23:20, 17 December 2016
In the philosophy of thermal and statistical physics, the Brownian ratchet or Feynman-Smoluchowski ratchet is a thought experiment about an apparent perpetual motion machine.
It was first analysed in 1912 by Polish physicist Marian Smoluchowski, and later popularized by American Nobel laureate physicist Richard Feynman in a physics lecture at the California Institute of Technology on May 11, 1962, during his Messenger Lectures series The Character of Physical Law in Cornell University.
The simple machine, consisting of a tiny paddle wheel and a ratchet, appears to be an example of a Maxwell's demon, able to extract useful work from random fluctuations (heat) in a system at thermal equilibrium in violation of the second law of thermodynamics.
Detailed analysis by Feynman and others showed why it cannot actually do this.
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Fiction cross-reference
Nonfiction cross-reference
External links:
- Brownian ratchet @ Wikipedia
Schematic figure of a Brownian ratchet (Feynman-Smoluchowski ratchet), a simple hypothetical mechanism used in a thought experiment by Marian Smoluchowski and Nobel laureate Richard Feynman to demonstrate the laws of thermodynamics.
The device is a tiny paddlewheel attached to a ratchet. It appears to be an example of a Maxwell's Demon, able to produce useful work from the random thermal motion of molecules at a constant temperature in violation of the Second Law of Thermodynamics. Feynman and others showed why it cannot actually produce work if T1 = T2
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