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This ratchet is also a restatement of Maxwell's Demon more or less. Feynman may have made this idea famous but he did not invent it... It was being discussed by Smoluchowski in 1912. Less full out incorrect statements on Wikipedia please. — Preceding unsigned comment added by 128.32.166.162 ( talk) 23:27, 13 November 2012 (UTC)
I am altering the article from "Feynman invented" to "idea made famous by Feynman". I will not add Smoluchowski without a reference. 131.111.8.96 ( talk) 22:33, 8 December 2009 (UTC)
Could someone explain simply why a brownian ratchet is self defeating?
This article makes a claim that ratchet slippage somehow prevents the ratchet device from producing work. The article should reference such a claim as an unproven theory until an appropriate reference is included in the article showing proof that slippage prevents the ratchet device from performing any work. Being one who has written many of simulations, include a trapdoor simulation, I believe such slippage is merely a technological issue, not a limitation. Thanks.-- PaulLowrance ( talk) 18:41, 28 May 2008 (UTC)
I added fact noted by Feynman that wheel would rotate in the other (backwards) direction if the temperature difference were reversed, as well as the parallel to why electrical diodes cannot extract useful work by rectifying thermal noise in a circuit at constant temperature. CharlesHBennett ( talk) 04:07, 30 March 2010 (UTC)
could someone add a picture to this page? I found a couple (including an animated one here: http://web.mit.edu/8.592/www/lectures/lec20/ (hover over the pic to see the animation)) but I didn't add them to the article because I wasn't sure of the copyright stuff.
The picture would be clearer if the ratchet were drawn with unsymmetrical teeth, with a gentle ramp leading up to a sudden drop, as in Feynman's drawing. CharlesHBennett ( talk) 04:07, 30 March 2010 (UTC)
could someone add a picture to this page? I found a couple (including an animated one here: http://web.mit.edu/8.592/www/lectures/lec20/ (hover over the pic to see the animation)) but I didn't add them to the article because I wasn't sure of the copyright stuff.
Thanks. -PB
On a small scale brownian motion could be seen a lots of pools of different temperature. -Jeff
It is not absolutely neccesary to use a pawl or even to have the machine rotate in one preferential direction to do work. An simple electric generator will output power no matter if the rotor goes one way or the other, AC currents carry useful energy even if they are null on average. Also at the brownian scale there are instantaneous large temperature fluctuations between the pawl and the ratchet even if they average over time.-Felix
I don't know of any support for the claim that Brownian motors extract useful work from thermal noise. Since this seems to violate the 2nd Law, and the 'citation needed' tag has been on a while, I think it should be removed. Comments? -- Chetvorno TALK 09:54, 30 August 2008 (UTC)
I know I am late to this debate but. Noise would need to be defined before stating whether or not the claim is possible or not. For example, equilibrium thermal noise cannot be used to do work; however, non-equilibrium noise can be used to do work. If the fluctuations are random but higher than the ambient thermal noise then yes they can be used to do work. This is how wrist watches work that neither have batteries nor a wind-up mechanism inside. — Preceding unsigned comment added by 128.32.166.162 ( talk) 23:32, 13 November 2012 (UTC)
As far as I can see, this experiment is mis-quoted or mis-described. The abstract in phys rev lett does not describe any ratchet at all, the symmetry breaking is provided by the vanes having different coating (soft, i.e. energy-absorbing inelastic) on the clockwise side. Furthermore, the phrasing at the beginning ("despite being theoretically proven") is a gross overstatement; the original paper does not claim to provide thermal equilibrium but explicitly refers to the "necessary" out of equilibrium environment given by the shaking of the gas. The experiment is probably worth mentioning but it should be done accurately. 207.172.169.230 ( talk) 14:56, 10 September 2010 (UTC)
This implies that other parts of the apparatus, notably the paddle and cog wheel, need not be massless. If that is so, and since these parts are all connected and moving in unison, why does it matter that the rod is massless? 86.160.83.115 ( talk) 01:16, 14 August 2011 (UTC)
If the pawl is encased in a vacuum, no particles hit the pawl to loosen it. Does this violate the second law of thermodynamics now since the ratchet should function? — Preceding unsigned comment added by LarsOlson ( talk • contribs) 00:47, 1 March 2014 (UTC)
Response to the above: sorry I should have explained further or drawn a diagram of what I meant. If the pawl and spring (and gear teeth) are located in a completely separate container, enclosed, and the shaft of the rod is connected only via a nano magnet so that the paddle side of the rod spins the other rod... this creates a vacuum in one section and room temperature in the other section. This creates an apparent differential in temperature (actually pressure) without having to continually maintain a difference in temperature since one side is a permanent vacuum (imperfect or perfect one).
Also there are some serious flaws in your argument about brownian motion of the pawl in a vacuum. Brownian motion of a solid object is not the same as a gas or liquid. Imagine the brownian motion of aluminum or steel. The atoms move extremely small amounts internally, compared to gas or liquid which moves much more. The whole point of the browian ratchet is to move and vibrate due to other molecules bombarding it, not internal atoms of the actual paddle moving (a solid with low vibrations). If it were true that the brownian ratchet were vibrating without any molecules or atoms bombarding it and it just moved all by itself due to internal vibrations.. there would be no need to draw these diagrams of the brownian ratchet with any particles hitting the paddle. Why not simplify the diagrams and remove all the particles hitting the paddle since you claim the particles aren't even necessary for massive vibrations to occur? Likely what you are doing here is simply trying to prove that the second law is always true (rather than trying to falsify it) and coming up with creative conspiracy theories that you have not actually tested experimentally nor thought through carefully. Are you saying for example that solid steel has just as much brownian motion as air particles smashing into the metal.. Look at some online websites of brownian motion of solid objects vs air and liquid.
Also, creating a hydrostatic pressure differential using two containers of water is another option. One container is taller than the other, and has more hydrostatic pressure at the bottom of the container due to gravity. Pressure is like energy per area... so two different pressures are like two different temperatures, creating a differential. It costs no energy or money to create a difference in hydrostatic pressure - gravity does the work for you. Consider two containers and the rod of the ratchet is connected via a nano magnet. Each compartment is separate, No seals are even needed due to the magnetism allowing two completely separate containers to be used for both halves of the system. The hydrostatic pressure is more in the paddle side of the ratchet, and the hydrostatic pressure is lower in the pawl/spring/gear side of the ratchet. One does not have to continually maintain a cold temperature on one side of the system - hydrostatic pressure is permanent without costing energy or money. Yes this could in fact be falsified and proven to not work: that is how science works and I am simply posting these thought experiments to allow people to further study the subject without such straw man inventions like the simple brownian ratchet which was fairly easily knocked down. — Preceding unsigned comment added by LarsOlson ( talk • contribs) 03:52, 18 July 2015 (UTC)
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Even if the brownian ratchet were to work (i.e. it were to do useful work), it would not satisfy the definition of a perpetual motion machine: "A perpetual motion machine is a hypothetical machine that can do work indefinitely without an energy source." The energy source is the ambient temperature of the air. This is a finite resource, and the ratchet would eventually reduce the air temperature via reducing the velocity of gas particles. Therefore, it is not an "aparrent perpetual motion machine". This phrase should be removed. ---- Cowlinator ( talk) 22:03, 20 February 2020 (UTC)
I think the article should probably contain some information on this study. It may also be relevant to other articles (which?). It's currently featured in 2020 in science in short form like so:
A rippling graphene-based energy-harvesting circuit with the potential to deliver "clean, limitless, low-voltage power for small devices" if adequately incorporated into a chip is demonstrated. [1] [2] [3]
Additional news report here. From this report of Physics World:
In the early 1960s, the Nobel laureate Richard Feynman popularized a thought experiment known as the “Brownian ratchet”, which had been conceived in 1912 by the Polish physicist Marian Smoluchowski. This involves a paddle wheel that is connected by an axle to a ratcheted gear. Both the paddle wheel and the ratchet are immersed in fluids. The system is imagined as being small enough so that the impact of a single molecule is sufficient to turn the paddle. Because of the ratchet, the paddle can only turn in one direction and therefore it appears that the Brownian motion of the paddle can be harnessed to do the work of turning the axle.
However, Feynman showed that if the two fluids were at the same temperature, collisions throughout the system would prevent this from happening. The only way work could be done, argued Feynman, is if the fluids are a different temperature, making the Brownian ratchet a heat engine.
In their new study, University of Arkansas physicist Paul Thibado and colleagues replaced the paddle with a freestanding sheet of graphene – a single layer of carbon atoms.
-- Prototyperspective ( talk) 10:25, 4 December 2020 (UTC)
References
I keep reading arguments where people are using “Feynman proved it therefore it must be true” to support their claim. I’ve listened to Feynman’s explanation, and no offense to his genius, but it makes no sense to me at all. Frankly, everyone who used the argument “Feynman said so, therefore it must be true” was appealing to authority, because as it turns out, the reason why what he was saying sounded like nonsense is because it was. We can now extract limitless energy produced by graphene, albeit little power, but still limitless energy. Yes, perpetual motion has finally been realized thanks to Brownian motion. Walid.Miran ( talk) 12:51, 24 February 2021 (UTC) [1]
I've undone the removal the "failed verification" tag on the passage that claimed Magnesco proved there was no net motion regardless of the shape of the teeth of the ratchet. The tag originally pointed to #History Error section but that does not seem to have any relevant discussion. I can't find any of the words "teeth", "tooth", or "shape" anywhere in the paper. Now Magnesco talks about periodic "potential functions" which we can interpret as the teeth of the ratchet, but I'm not seeing a claim either that any shape protential function will result in no net motion. Indeed, the whole thrust of the paper is that "net drift speed" is possible in some circumstances. If you think that this paper does support the claim, then please specify exactly where it does so before removing the tag again. Spinning Spark 14:16, 26 September 2022 (UTC)
This article is rated Start-class on Wikipedia's
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This ratchet is also a restatement of Maxwell's Demon more or less. Feynman may have made this idea famous but he did not invent it... It was being discussed by Smoluchowski in 1912. Less full out incorrect statements on Wikipedia please. — Preceding unsigned comment added by 128.32.166.162 ( talk) 23:27, 13 November 2012 (UTC)
I am altering the article from "Feynman invented" to "idea made famous by Feynman". I will not add Smoluchowski without a reference. 131.111.8.96 ( talk) 22:33, 8 December 2009 (UTC)
Could someone explain simply why a brownian ratchet is self defeating?
This article makes a claim that ratchet slippage somehow prevents the ratchet device from producing work. The article should reference such a claim as an unproven theory until an appropriate reference is included in the article showing proof that slippage prevents the ratchet device from performing any work. Being one who has written many of simulations, include a trapdoor simulation, I believe such slippage is merely a technological issue, not a limitation. Thanks.-- PaulLowrance ( talk) 18:41, 28 May 2008 (UTC)
I added fact noted by Feynman that wheel would rotate in the other (backwards) direction if the temperature difference were reversed, as well as the parallel to why electrical diodes cannot extract useful work by rectifying thermal noise in a circuit at constant temperature. CharlesHBennett ( talk) 04:07, 30 March 2010 (UTC)
could someone add a picture to this page? I found a couple (including an animated one here: http://web.mit.edu/8.592/www/lectures/lec20/ (hover over the pic to see the animation)) but I didn't add them to the article because I wasn't sure of the copyright stuff.
The picture would be clearer if the ratchet were drawn with unsymmetrical teeth, with a gentle ramp leading up to a sudden drop, as in Feynman's drawing. CharlesHBennett ( talk) 04:07, 30 March 2010 (UTC)
could someone add a picture to this page? I found a couple (including an animated one here: http://web.mit.edu/8.592/www/lectures/lec20/ (hover over the pic to see the animation)) but I didn't add them to the article because I wasn't sure of the copyright stuff.
Thanks. -PB
On a small scale brownian motion could be seen a lots of pools of different temperature. -Jeff
It is not absolutely neccesary to use a pawl or even to have the machine rotate in one preferential direction to do work. An simple electric generator will output power no matter if the rotor goes one way or the other, AC currents carry useful energy even if they are null on average. Also at the brownian scale there are instantaneous large temperature fluctuations between the pawl and the ratchet even if they average over time.-Felix
I don't know of any support for the claim that Brownian motors extract useful work from thermal noise. Since this seems to violate the 2nd Law, and the 'citation needed' tag has been on a while, I think it should be removed. Comments? -- Chetvorno TALK 09:54, 30 August 2008 (UTC)
I know I am late to this debate but. Noise would need to be defined before stating whether or not the claim is possible or not. For example, equilibrium thermal noise cannot be used to do work; however, non-equilibrium noise can be used to do work. If the fluctuations are random but higher than the ambient thermal noise then yes they can be used to do work. This is how wrist watches work that neither have batteries nor a wind-up mechanism inside. — Preceding unsigned comment added by 128.32.166.162 ( talk) 23:32, 13 November 2012 (UTC)
As far as I can see, this experiment is mis-quoted or mis-described. The abstract in phys rev lett does not describe any ratchet at all, the symmetry breaking is provided by the vanes having different coating (soft, i.e. energy-absorbing inelastic) on the clockwise side. Furthermore, the phrasing at the beginning ("despite being theoretically proven") is a gross overstatement; the original paper does not claim to provide thermal equilibrium but explicitly refers to the "necessary" out of equilibrium environment given by the shaking of the gas. The experiment is probably worth mentioning but it should be done accurately. 207.172.169.230 ( talk) 14:56, 10 September 2010 (UTC)
This implies that other parts of the apparatus, notably the paddle and cog wheel, need not be massless. If that is so, and since these parts are all connected and moving in unison, why does it matter that the rod is massless? 86.160.83.115 ( talk) 01:16, 14 August 2011 (UTC)
If the pawl is encased in a vacuum, no particles hit the pawl to loosen it. Does this violate the second law of thermodynamics now since the ratchet should function? — Preceding unsigned comment added by LarsOlson ( talk • contribs) 00:47, 1 March 2014 (UTC)
Response to the above: sorry I should have explained further or drawn a diagram of what I meant. If the pawl and spring (and gear teeth) are located in a completely separate container, enclosed, and the shaft of the rod is connected only via a nano magnet so that the paddle side of the rod spins the other rod... this creates a vacuum in one section and room temperature in the other section. This creates an apparent differential in temperature (actually pressure) without having to continually maintain a difference in temperature since one side is a permanent vacuum (imperfect or perfect one).
Also there are some serious flaws in your argument about brownian motion of the pawl in a vacuum. Brownian motion of a solid object is not the same as a gas or liquid. Imagine the brownian motion of aluminum or steel. The atoms move extremely small amounts internally, compared to gas or liquid which moves much more. The whole point of the browian ratchet is to move and vibrate due to other molecules bombarding it, not internal atoms of the actual paddle moving (a solid with low vibrations). If it were true that the brownian ratchet were vibrating without any molecules or atoms bombarding it and it just moved all by itself due to internal vibrations.. there would be no need to draw these diagrams of the brownian ratchet with any particles hitting the paddle. Why not simplify the diagrams and remove all the particles hitting the paddle since you claim the particles aren't even necessary for massive vibrations to occur? Likely what you are doing here is simply trying to prove that the second law is always true (rather than trying to falsify it) and coming up with creative conspiracy theories that you have not actually tested experimentally nor thought through carefully. Are you saying for example that solid steel has just as much brownian motion as air particles smashing into the metal.. Look at some online websites of brownian motion of solid objects vs air and liquid.
Also, creating a hydrostatic pressure differential using two containers of water is another option. One container is taller than the other, and has more hydrostatic pressure at the bottom of the container due to gravity. Pressure is like energy per area... so two different pressures are like two different temperatures, creating a differential. It costs no energy or money to create a difference in hydrostatic pressure - gravity does the work for you. Consider two containers and the rod of the ratchet is connected via a nano magnet. Each compartment is separate, No seals are even needed due to the magnetism allowing two completely separate containers to be used for both halves of the system. The hydrostatic pressure is more in the paddle side of the ratchet, and the hydrostatic pressure is lower in the pawl/spring/gear side of the ratchet. One does not have to continually maintain a cold temperature on one side of the system - hydrostatic pressure is permanent without costing energy or money. Yes this could in fact be falsified and proven to not work: that is how science works and I am simply posting these thought experiments to allow people to further study the subject without such straw man inventions like the simple brownian ratchet which was fairly easily knocked down. — Preceding unsigned comment added by LarsOlson ( talk • contribs) 03:52, 18 July 2015 (UTC)
Hello fellow Wikipedians,
I have just modified one external link on Brownian ratchet. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at {{
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).
This message was posted before February 2018.
After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than
regular verification using the archive tool instructions below. Editors
have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the
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(last update: 5 June 2024).
Cheers.— InternetArchiveBot ( Report bug) 13:29, 9 November 2016 (UTC)
Even if the brownian ratchet were to work (i.e. it were to do useful work), it would not satisfy the definition of a perpetual motion machine: "A perpetual motion machine is a hypothetical machine that can do work indefinitely without an energy source." The energy source is the ambient temperature of the air. This is a finite resource, and the ratchet would eventually reduce the air temperature via reducing the velocity of gas particles. Therefore, it is not an "aparrent perpetual motion machine". This phrase should be removed. ---- Cowlinator ( talk) 22:03, 20 February 2020 (UTC)
I think the article should probably contain some information on this study. It may also be relevant to other articles (which?). It's currently featured in 2020 in science in short form like so:
A rippling graphene-based energy-harvesting circuit with the potential to deliver "clean, limitless, low-voltage power for small devices" if adequately incorporated into a chip is demonstrated. [1] [2] [3]
Additional news report here. From this report of Physics World:
In the early 1960s, the Nobel laureate Richard Feynman popularized a thought experiment known as the “Brownian ratchet”, which had been conceived in 1912 by the Polish physicist Marian Smoluchowski. This involves a paddle wheel that is connected by an axle to a ratcheted gear. Both the paddle wheel and the ratchet are immersed in fluids. The system is imagined as being small enough so that the impact of a single molecule is sufficient to turn the paddle. Because of the ratchet, the paddle can only turn in one direction and therefore it appears that the Brownian motion of the paddle can be harnessed to do the work of turning the axle.
However, Feynman showed that if the two fluids were at the same temperature, collisions throughout the system would prevent this from happening. The only way work could be done, argued Feynman, is if the fluids are a different temperature, making the Brownian ratchet a heat engine.
In their new study, University of Arkansas physicist Paul Thibado and colleagues replaced the paddle with a freestanding sheet of graphene – a single layer of carbon atoms.
-- Prototyperspective ( talk) 10:25, 4 December 2020 (UTC)
References
I keep reading arguments where people are using “Feynman proved it therefore it must be true” to support their claim. I’ve listened to Feynman’s explanation, and no offense to his genius, but it makes no sense to me at all. Frankly, everyone who used the argument “Feynman said so, therefore it must be true” was appealing to authority, because as it turns out, the reason why what he was saying sounded like nonsense is because it was. We can now extract limitless energy produced by graphene, albeit little power, but still limitless energy. Yes, perpetual motion has finally been realized thanks to Brownian motion. Walid.Miran ( talk) 12:51, 24 February 2021 (UTC) [1]
I've undone the removal the "failed verification" tag on the passage that claimed Magnesco proved there was no net motion regardless of the shape of the teeth of the ratchet. The tag originally pointed to #History Error section but that does not seem to have any relevant discussion. I can't find any of the words "teeth", "tooth", or "shape" anywhere in the paper. Now Magnesco talks about periodic "potential functions" which we can interpret as the teeth of the ratchet, but I'm not seeing a claim either that any shape protential function will result in no net motion. Indeed, the whole thrust of the paper is that "net drift speed" is possible in some circumstances. If you think that this paper does support the claim, then please specify exactly where it does so before removing the tag again. Spinning Spark 14:16, 26 September 2022 (UTC)