Talk:Perpetual motion

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What about atoms?[edit]

Specifically, electrons orbiting a nucleus. It's not a machine or anything artificial, but does their motion continue forever? Or at some point (theoretically) they reach maximum entropy, something causes them to stop. Can this mean something moving forever, rather than just a machine, an object moving through space will go forever, unless some other force acts on it, stops it. The snare (talk) 05:01, 10 May 2016 (UTC)

They don't "orbit" in anything close to the planetary sense of that word. Our article on atomic theory discusses the evolution of scientific understanding of the nature of electronic behavior near a nucleus. DMacks (talk) 05:17, 10 May 2016 (UTC)
it is known for at least 100 years that electrons do not rotate around nucleus and that is why Pauling developed the notion of orbitals, but even this notion is not properly understood by some (it is the positions in space that can be occupied by electron, but electron is just hanging in one position depending on distribution of electromagnetic forces between nuclei and him or within one nucleus between all electrons and parental nucleus) — Preceding unsigned comment added by 134.7.193.46 (talk) 06:15, 29 July 2016 (UTC)

My understanding: Yes the electrons are in "motion" (they have energy), with the electron appearing in different places every time that it is observed. One can take energy out the atom until it reaches its lowest energy state, whereupon no more energy can be taken out, but the electron, even in its lowest energy state, still has some energy. So, the ground-state atom is in "perpetual motion", but it is not a "machine" that can be used to accomplish some sort of work. Correct me if I'm wrong about this. Isambard Kingdom (talk) 12:57, 19 March 2017 (UTC)

Thermodynamics cover only the part of Physics[edit]

it deals only with motion of particles due to T (it is caused by combined action of gravitational and EM fields, but indirectly), but not with the motion which is attributed to direct field's action on a matter...in this way exists not only the eternal motion, but and the eternal engine (it is actually the obvious fact since if exist an eternal motion, then must be and work done by this motion - eternal work)...so laws of thermodynamics are governing not all physical processes, but only temperature cycles...however the 1st law of TD is not the law of TD but general law of everything, since it is states that nothing appears from nothing...and the 2nd law of TD is actually again the general law of physics directly derived from the first and governs the differences in energy sizes (the most energetically favorable is minimal energy rather than higher energy).

The first law of Thermodynamics is a consequence of the conservation of Energy. Which according to Noether's theorem, it boils down to the time translation symmetry of Physics' laws. So, no it isn't a general law that says that "nothing appears from nothing". The second law isn't derived from the first, and it has nothing to do with energy sizes, but with entropy; that is the quality of each energy quantity. Finally, both laws are very strong and can be found in all parts of Physics (big/small scales, fast/slow speeds). Mlliarm (talk) 22:17, 24 June 2017 (UTC)

Time crystals are not perpetual motion machines.[edit]

They're driven. Adding citations that don't back up your claim does not make it any less wrong.

I agree that they are not "perpetual motion machines" and do not violate the laws of thermodynamics;[1],[2] the current paragraph is not supported by the sources. Time crystals fit the literal definition of "perpetual motion", but because energy cannot be extracted from the motion - they are in the quantum "ground state" of minimum energy - they do not fit the modern definition of "perpetual motion machine" as a device which produces or stores energy perpetually. This is not because they are "driven", or are an "open system" as stated in the current text, but because their "motion" does not represent energy at all; they possess "motion without energy".[3] For the same reason they do not violate the first or second laws of thermodynamics.[4] The paragraph needs to be rewritten. --ChetvornoTALK 22:15, 19 September 2017 (UTC)

Artificial Water Cycle[edit]

How about if you used the water cycle, of water evaporating and condensing on large scale in a closed system? Where evaporation is caused by heating, then the water condenses, and while it condenses at a high height it is allowed to pass down like a hydro electric systems, to pass through hydro electric turbines to come down to be evaporated again. This can result in a cycle of perpetual motion. — Preceding unsigned comment added by Susanscottish (talkcontribs) 12:25, 12 November 2018 (UTC)

No, the second law of thermodynamics says that all closed-cycle systems are irreversible, which means that some of the energy is lost to the environment as they operate. A system such as you describe has many sources of energy loss: friction of the turbines, electric resistance in the wires, aerodynamic drag of moving water vapor, viscous drag of the moving water flowing through pipes, radiation of heat released by the condensing water, etc. The water cycle on Earth requires a constant huge input of heat from the Sun, which is dissipated into the environment. --ChetvornoTALK 13:14, 12 November 2018 (UTC)

PMMs of the third kind[edit]

I think we should add that PMMs of the third kind are the only kind that aren't strictly forbidden, that is they are at least not technically impossible in principle (in contrast, machines of the first and second kind are strictly forbidden even just in principle). In practice, dissipative forces will always exist in any system where degrees of freedom are neglected, and so PMMs of the third kind aren't feasible beyond simple isolated systems at the atomic level. Also if they were possible in practice, they would only be useful as a form of energy storage. They could not be used as a source of energy generation. 132.160.70.36 (talk) 03:22, 30 October 2019 (UTC)

Woodward's wheel[edit]

F.G.Woodward's hoop wheel that is supported by two rollers is an interesting try. It should be included. 95.178.135.0 (talk) 22:11, 12 May 2020 (UTC)