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Old 4th October 2020, 10:24 AM   #41
hecd2
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Originally Posted by Gord_in_Toronto View Post
Having a little more time, I went back and viewed the video in the OP. The animation contains a switch. This is a "Maxwell Demon" with electrons not molecules as in the direct classical sense. The circuit actually adds another step in the "energy extraction" process.

Per https://www.chem.uci.edu/undergraduate/applets/bounce/demon.htm"



YMMV. IANAP.
Isnít the switch there simply to discharge the energy previously built up by the controversial process in the capacitor through the lamp. I donít see it as a Maxwellís demon.
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Old 4th October 2020, 10:26 AM   #42
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Originally Posted by Captain_Swoop View Post
error in their instrumentation?
Without seeing the experimental set up we don't know.

I have seen claims that "demonstrate" the extraction of energy from the quantum vacuum ZPE field which used an AC to DC converter as initiator for the process. Unfortunately, the DC output from a converter (every converter) is not completely smooth, some residual AC sneaks though and is interpreted as free energy. I always suggest the AC/DC converter be replaced with real batteries. And repeat the demonstration inside a Faraday Cage.

If these guys are right, forget the cut of the profits from selling watch batteries and go for the Nobel Prize!
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Old 4th October 2020, 10:51 AM   #43
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Originally Posted by shemp View Post
Same here. A neighbor had a lamp that if you put your ear close to it you could hear country music.

Ours was oldies and easy listening, so not quite so bad.
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Old 4th October 2020, 10:53 AM   #44
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Originally Posted by Gord_in_Toronto View Post
If these guys are right, forget the cut of the profits from selling watch batteries and go for the Nobel Prize!

I don't think they'll care much about the Nobel when they are multi-trillionaires.
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Old 4th October 2020, 11:59 AM   #45
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Originally Posted by theprestige View Post
Good guess, but actually I was just thinking very ignorantly about Brownian motion.

At the risk of being obviously ignorant again, if Brownian motion requires an input of heat, then "Physicists Build Circuit That Generates Clean, Limitless Power From Graphene" seems like an obvious and inexcusable lie. The actual "clean, limitless power" would be coming from whatever produces the heat.
If you can violate the 2nd law of thermodynamics, then you do have essentially unlimited energy. Yes, energy is conserved, but without the 2nd law, you can basically just recycle it endlessly. Whatever you use it for will end up producing heat, and you just recycle that heat back into more energy.

The 2nd law is basically a claim about statistical averages. At the macroscopic scale, deviations from statistical average become too small to matter, but they can be observed at microscopic scales, so there are microscopic violations of the 2nd law. But they don't matter at that scale, at least not in terms of energy production. It would be world-changing if we could violate the 2nd law on a macroscopic level.

I expect that we'll never violate it at macroscopic scales.
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Old 12th October 2020, 04:56 PM   #46
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Oh. Look. Not over there, here:

A YouTube video from November 2017. "A Potential Source of Clean, Limitless Energy"

YouTube Video This video is not hosted by the ISF. The ISF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website.
I AGREE


The diagram has become a bit more complicated in three years (an effort to answer critics?)

Something so simple should be powering our way to the Outer Limits after three years of development of such a radical, World changing discovery.

For once for YouTube the comments seem as skeptical as the majority of those in this forum.

It did not work then. It does not work now. It cannot work.

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Old 12th October 2020, 05:25 PM   #47
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Honestly I don't see why it wouldn't work in principle. You put heat energy into the graphene to produce motion. Then you harness that motion to do work. As long as you have a source of heat (sunlight, wood fire, radioactive decay, whatever), why wouldn't you be able to get work out? We have tons of other examples of converting heat into work.
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Old 12th October 2020, 05:50 PM   #48
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Originally Posted by theprestige View Post
Honestly I don't see why it wouldn't work in principle. You put heat energy into the graphene to produce motion. Then you harness that motion to do work. As long as you have a source of heat (sunlight, wood fire, radioactive decay, whatever), why wouldn't you be able to get work out? We have tons of other examples of converting heat into work.
Sure. Carnot engine for instance.

The claim is that it produces energy in a system that's already at max entropy. Not going to happen.
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Old 12th October 2020, 06:19 PM   #49
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The claim is entirely uncoupled from the mechanism. I'm not saying unlimited power is possible. I'm saying power from Brownian motion should be possible, given a heat source.
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Old 12th October 2020, 07:55 PM   #50
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Originally Posted by theprestige View Post
Honestly I don't see why it wouldn't work in principle. You put heat energy into the graphene to produce motion. Then you harness that motion to do work. As long as you have a source of heat (sunlight, wood fire, radioactive decay, whatever), why wouldn't you be able to get work out? We have tons of other examples of converting heat into work.
The article is more than a little confusing on that front. If you run a heat engine, the power output and the efficiency scale with the difference in temperature between your heat source and your sink. But they don't talk about that. They seem to be implying (but don't outright state) that they can get power out without needing a cold sink. That's the part that's causing controversy. If they could do that (and I doubt they can), then that's revolutionary. If they can't, then they've produced and overly complicated and expensive thermoelectric generator. That's of no use to anyone, even if it is of interest purely for scientific curiosity.
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Old 12th October 2020, 09:35 PM   #51
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The "device" appears to be an electric version of a Brownian_ratchetWP.

Quote:
Diodes are an electrical analog of the ratchet and pawl, and for the same reason cannot produce useful work by rectifying Johnson noise in a circuit at uniform temperature.
Quote:
Lťon Brillouin in 1950 discussed an electrical circuit analogue that uses a rectifier (such as a diode) instead of a ratchet. The idea was the diode would rectify the Johnson noise thermal current fluctuations produced by the resistor, generating a direct current which could be used to perform work. In the detailed analysis it was shown that the thermal fluctuations within the diode generate an electromotive force that cancels the voltage from rectified current fluctuations. Therefore, just as with the ratchet, the circuit will produce no useful energy if all the components are at thermal equilibrium (at the same temperature); a DC current will be produced only when the diode is at a lower temperature than the resistor.[12]
It cannot be a perpetual motion device that extracts energy from nothing.

Don't take my word for it. Argue with Richard Feynman.

If you want to run your watch for free, for forever, just build a tiny motor built on the same principle as the clocks that run on atmospheric pressure. Or buy a self-winding watch.
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Old 12th October 2020, 10:15 PM   #52
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Originally Posted by theprestige View Post
The claim is entirely uncoupled from the mechanism. I'm not saying unlimited power is possible. I'm saying power from Brownian motion should be possible, given a heat source.
Why the "heat source" qualifier? If you had a mechanism to extract energy from isothermal brownian motion, why would additional heat be necessary?
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Old 12th October 2020, 11:42 PM   #53
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Originally Posted by BowlOfRed View Post
Why the "heat source" qualifier? If you had a mechanism to extract energy from isothermal brownian motion, why would additional heat be necessary?
Because there's a difference between violating the 1st law of thermodynamics and violating the 2nd law. If you could violate the 2nd law but not the first, then extracting energy from isothermal brownian motion would cool your system, and you'd run out of energy once that system cooled down too much. There's more than enough ambient heat around to warm it back up for free, but you would still need to keep pouring heat into the system to keep it running. It's just that you could do that part for essentially free.

And if you've got a heat source above ambient temperature, then you're just running a standard heat engine which can work without violating either 1st or 2nd law.
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Old 13th October 2020, 04:52 AM   #54
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Originally Posted by theprestige View Post
Honestly I don't see why it wouldn't work in principle. You put heat energy into the graphene to produce motion. Then you harness that motion to do work. As long as you have a source of heat (sunlight, wood fire, radioactive decay, whatever), why wouldn't you be able to get work out? We have tons of other examples of converting heat into work.
We don't have any examples of converting heat into work, deriving useful work from heat is thermodynamically impossible. Heat engines don't just sit there and consume ambient heat, they produce work from the flow of heat across a temperature difference. This widget, if it worked as claimed, would create a temperature difference between the graphene and the surrounding environment, and not only do so without power input, but while generating power output. You could use it to, for instance, build a refrigerator that generates energy while cooling food.
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Old 13th October 2020, 06:31 AM   #55
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Originally Posted by BowlOfRed View Post
Why the "heat source" qualifier? If you had a mechanism to extract energy from isothermal brownian motion, why would additional heat be necessary?
I don't understand your use of "isothermal" here. Extracting work from the Brownian motion necessarily lowers the temperature of the graphene. The motion necessarily slows until no more work can be extracted, unless you keep warming the graphene back up.
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Old 13th October 2020, 06:57 AM   #56
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Originally Posted by cjameshuff View Post
We don't have any examples of converting heat into work, deriving useful work from heat is thermodynamically impossible. Heat engines don't just sit there and consume ambient heat, they produce work from the flow of heat across a temperature difference. This widget, if it worked as claimed, would create a temperature difference between the graphene and the surrounding environment, and not only do so without power input, but while generating power output. You could use it to, for instance, build a refrigerator that generates energy while cooling food.
Maybe I used the wrong words. I'm talking about well known things like heating water to produce pressurized steam and then extracting work from it. As long as you can keep providing heat to the system, you can extract work indefinitely.

Anyway, that's not my main interest here. It seems like there are two separate claims. One claim is that Brownian motion in graphene can be used to generate electricity. This is not obviously wrong to me. As far as I can tell, it doesn't violate any physical laws in principle. Put heat in, get motion, harness the motion to generate electricity, use the electricity to do work. The main questions here seem to be whether it's possible to harness the motion, and whether the motion-electricity-power process is efficient enough to do useful work.

The other claim is that Brownian motion in graphene is an unlimited source of power. This claim is obviously wrong to me. Brownian motion still needs an energy input, and that energy still gets consumed when it's converted to work. Even if the first claim is true, the power output is going to be limited by whatever energy source you're using to heat the graphene.
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Old 13th October 2020, 06:59 AM   #57
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My first thought was those "antigravity machines" that really do levitate, but are actually using electrical current to ionize the air and generate thrust. Assuming it isn't a deliberate hoax, they may be getting the results that they describe but they aren't coming from the source to which they attribute them.

EDIT: Looking online, I see that researchers have successfully engineered piezoelectric properties into graphene, so there is already graphene that generates electricity, but through other means.

Last edited by Armitage72; 13th October 2020 at 07:05 AM.
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Old 13th October 2020, 07:08 AM   #58
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Originally Posted by theprestige View Post
It seems like there are two separate claims. One claim is that Brownian motion in graphene can be used to generate electricity. This is not obviously wrong to me. As far as I can tell, it doesn't violate any physical laws in principle.
It violates the Second Law of Thermodynamics, because the formulation of the claim includes no necessity for a second body at a lower temperature to which heat is transferred. If the proposed effect is real, it would therefore be possible to extract energy from an already cool reservoir, transfer it to a hotter reservoir, and decrease the entropy of the universe. If the claim is true, then the entire science of thermodynamics is incorrect. That's not the same as saying that it isn't true; but the burden of proof on this one is going to be set extremely high.

Dave
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Old 13th October 2020, 07:17 AM   #59
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Originally Posted by Dave Rogers View Post
It violates the Second Law of Thermodynamics, because the formulation of the claim includes no necessity for a second body at a lower temperature to which heat is transferred. If the proposed effect is real, it would therefore be possible to extract energy from an already cool reservoir, transfer it to a hotter reservoir, and decrease the entropy of the universe. If the claim is true, then the entire science of thermodynamics is incorrect. That's not the same as saying that it isn't true; but the burden of proof on this one is going to be set extremely high.
Bear with me for a moment here. I'm decoupling the two claims. There's the claim that electricity can be generated from Brownian motion. And there's the claim that this can be done indefinitely without reheating the power source. The researchers combine the two claims. This is obviously problematic because the second claim violates a conservation law.

I'm asking if the first claim is reasonable on its own.
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Old 13th October 2020, 07:20 AM   #60
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Originally Posted by theprestige View Post
Bear with me for a moment here. I'm decoupling the two claims. There's the claim that electricity can be generated from Brownian motion. And there's the claim that this can be done indefinitely without reheating the power source. The researchers combine the two claims. This is obviously problematic because the second claim violates a conservation law.

I'm asking if the first claim is reasonable on its own.
And I'm commenting only on the first one. Generating energy from Brownian motion, on its own, violates the Second Law of Thermodynamics. Generating "limitless" power from Brownian motion violates the First Law. The Second is no less a physical law than the First.

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Old 13th October 2020, 07:27 AM   #61
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Originally Posted by Dave Rogers View Post
And I'm commenting only on the first one. Generating energy from Brownian motion, on its own, violates the Second Law of Thermodynamics.
This is the part I don't understand.
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Old 13th October 2020, 07:35 AM   #62
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Originally Posted by theprestige View Post
This is the part I don't understand.
Suppose we can extract electrical power from Brownian motion in a tank of liquid, initially at, say, 20 degrees Celsius. This can only be done by reducing the thermal motion of the molecules of liquid in the tank. This must result in the overall cooling of the tank of liquid. Suppose now that we use the electrical power to heat a second tank of liquid, initially at 30 degrees Celsius. The cold liquid gets colder, and the hot liquid gets hotter. No other change is taking place. This violates the Clausius statement of the Second Law of Thermodynamics: "Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time."

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Old 13th October 2020, 08:04 AM   #63
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An analogy may help to understand what's being said (it's an illustration, not an argument ). If you compare heat energy-generation to water energy generation, it might make more sense.

To generate energy from water, you need a reservoir at a higher altitude. You release water from that, and it flows downhill, allowing you to capture energy from that motion.

In a similar manner, to get energy from heat, you need a hot reservoir. The heat flows from the hot reservoir to a colder one (from a fire to the water in a boiler, for example), and you can pull work from that flow of heat.

With water, if the two reservoirs are at the same height, there's no flow, so you can't get work from it. Similarly with heat, if there's no temperature difference, there's no flow, and you can't get work. It's the flow of heat from hot to cold that we use to generate power.

Basically, they seem to be implying that they can run the water uphill, or between two equal-height reservoirs, and extract energy from that flow (more than it takes to cause the motion). If you can do that, then the three laws of thermodynamics become the mild suggestions of thermodynamics .
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Old 13th October 2020, 08:45 AM   #64
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Originally Posted by theprestige View Post
I don't understand your use of "isothermal" here. Extracting work from the Brownian motion necessarily lowers the temperature of the graphene. The motion necessarily slows until no more work can be extracted, unless you keep warming the graphene back up.
The system is initially isothermal. In reality, it will stay so.

The claim is of a device that can produce a temperature difference as useful work is extracted. You don't need to do anything special to restore the heat that is lost, the graphene is now surrounded by an environment that is warmer than it. Not only that, you could even run heat engines off the difference between the environment and the graphene, and run the whole contraption until it has cooled everything around it to 0K. You really don't see anything wrong with that?
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Old 13th October 2020, 08:47 AM   #65
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Originally Posted by cjameshuff View Post
Not only that, you could even run heat engines off the difference between the environment and the graphene, and run the whole contraption until it has cooled everything around it to 0K.
Well, except that it would take an infinite amount of time to get there, because of the Third Law.

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Old 13th October 2020, 09:03 AM   #66
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Originally Posted by Hellbound View Post
An analogy may help to understand what's being said (it's an illustration, not an argument : p). If you compare heat energy-generation to water energy generation, it might make more sense.

To generate energy from water, you need a reservoir at a higher altitude. You release water from that, and it flows downhill, allowing you to capture energy from that motion.

In a similar manner, to get energy from heat, you need a hot reservoir. The heat flows from the hot reservoir to a colder one (from a fire to the water in a boiler, for example), and you can pull work from that flow of heat.

With water, if the two reservoirs are at the same height, there's no flow, so you can't get work from it. Similarly with heat, if there's no temperature difference, there's no flow, and you can't get work. It's the flow of heat from hot to cold that we use to generate power.

Basically, they seem to be implying that they can run the water uphill, or between two equal-height reservoirs, and extract energy from that flow (more than it takes to cause the motion). If you can do that, then the three laws of thermodynamics become the mild suggestions of thermodynamics : D.
Originally Posted by cjameshuff View Post
The system is initially isothermal. In reality, it will stay so.

The claim is of a device that can produce a temperature difference as useful work is extracted. You don't need to do anything special to restore the heat that is lost, the graphene is now surrounded by an environment that is warmer than it. Not only that, you could even run heat engines off the difference between the environment and the graphene, and run the whole contraption until it has cooled everything around it to 0K. You really don't see anything wrong with that?
Originally Posted by Dave Rogers View Post
Suppose we can extract electrical power from Brownian motion in a tank of liquid, initially at, say, 20 degrees Celsius. This can only be done by reducing the thermal motion of the molecules of liquid in the tank. This must result in the overall cooling of the tank of liquid. Suppose now that we use the electrical power to heat a second tank of liquid, initially at 30 degrees Celsius. The cold liquid gets colder, and the hot liquid gets hotter. No other change is taking place. This violates the Clausius statement of the Second Law of Thermodynamics: "Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time."
I guess I'm not thinking about this in the correct way.

I'm thinking of something like a tiny whaterwheel: A molecule of water strikes the wheel, causing it to turn. If the wheel is connected to a generator, this transfer of motion can be used to generate electricity without violating any laws.

In the case of the water wheel, the energy of motion is produced by gravity.

In this case, the energy of motion is produced by heat. I don't see how the motion is magically different because it's been produced by heat. The molecule or atom is still generating power through motion.

Is the problem that the generating circuit must warm up to the same degree that the power source (the graphene) cools down?
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Old 13th October 2020, 09:08 AM   #67
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Originally Posted by Dave Rogers View Post
Well, except that it would take an infinite amount of time to get there, because of the Third Law.
Well, if you assume the laws of thermodynamics are valid, then the device just doesn't work. If you throw out the first two, I don't know why you'd keep the third around. Maybe it reaches a negative effective temperature when it gets low enough and pulls the last bits of energy out before producing energy out of nowhere from zero-point fluctuations...

Or maybe it's a poorly-engineered condenser microphone cobbled together by people who don't even understand diodes, that requires an external power supply to provide a voltage bias and may happen to function slightly as a heat pump.
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Old 13th October 2020, 09:10 AM   #68
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Originally Posted by theprestige View Post
I guess I'm not thinking about this in the correct way.

I'm thinking of something like a tiny whaterwheel: A molecule of water strikes the wheel, causing it to turn. If the wheel is connected to a generator, this transfer of motion can be used to generate electricity without violating any laws.

In the case of the water wheel, the energy of motion is produced by gravity.

In this case, the energy of motion is produced by heat. I don't see how the motion is magically different because it's been produced by heat. The molecule or atom is still generating power through motion.

Is the problem that the generating circuit must warm up to the same degree that the power source (the graphene) cools down?
You see no problem with a water wheel sitting in a level trough of water, spontaneously pushing water to one side of the trough while doing mechanical work?
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Old 13th October 2020, 09:40 AM   #69
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Originally Posted by theprestige View Post
I'm thinking of something like a tiny whaterwheel: A molecule of water strikes the wheel, causing it to turn. If the wheel is connected to a generator, this transfer of motion can be used to generate electricity without violating any laws.
The waterwheel is exploiting a gradient. There is a difference between the moving water at the bottom of the wheel and the non-moving ground. The wheel can do work on this difference.

Take the wheel and disconnect it from the ground and put it underwater in the middle of a fast-moving river. There's lots of energy there, but without a gradient, the wheel cannot extract work from it.


Quote:
In the case of the water wheel, the energy of motion is produced by gravity.
The water wheel is moving the water to a lower potential energy and it might be slowing water to a lower kinetic energy. It has a place to lower water to, and it has a ground that it can slow the water relative to.

Quote:
In this case, the energy of motion is produced by heat. I don't see how the motion is magically different because it's been produced by heat. The molecule or atom is still generating power through motion.
In a isothermal bath, there's no way to slow anything down to extract the energy. Your equipment must be just as hot, so your molecules are also moving quickly.
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Old 13th October 2020, 09:42 AM   #70
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Originally Posted by cjameshuff View Post
You see no problem with a water wheel sitting in a level trough of water, spontaneously pushing water to one side of the trough while doing mechanical work?
I don't see a level trough of water in the scenario I'm looking at. Let's move on from the analogy back to the thing itself:

I have a bunch of molecules (atoms?) bouncing around. I hook up a device such that when a molecule hits it, it generates some electricity. The bouncing of the atoms is necessarily dampened by this process. How is the generation of electricity not possible in this scenario?
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Old 13th October 2020, 09:49 AM   #71
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Originally Posted by theprestige View Post
I don't understand your use of "isothermal" here. Extracting work from the Brownian motion necessarily lowers the temperature of the graphene. The motion necessarily slows until no more work can be extracted, unless you keep warming the graphene back up.
If this scheme could cool the graphene, we could then get work out of just letting it warm back up. Although you might think of cold things having less energy, we can get work out of that state.

If we had something that could be kept cold forever, we would have a near perpetual energy machine, just by extracting work. We could create a heat "water wheel" and power it by letting the rest of the heat in the universe fall through it.
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Old 13th October 2020, 09:52 AM   #72
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Originally Posted by theprestige View Post
I don't see a level trough of water in the scenario I'm looking at. Let's move on from the analogy back to the thing itself:

I have a bunch of molecules (atoms?) bouncing around. I hook up a device such that when a molecule hits it, it generates some electricity. The bouncing of the atoms is necessarily dampened by this process. How is the generation of electricity not possible in this scenario?
The problem here is that you have introduced a device that can not exist.

By what means does it generate electricity and "dampen the bouncing" (reduce temperature), if the device is at the same temperature? Cooling the atoms will require energy, not produce it.
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Old 13th October 2020, 09:52 AM   #73
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Originally Posted by theprestige View Post
The bouncing of the atoms is necessarily dampened by this process.
As your equipment is at the same temperature (and has atoms bouncing at the same speed), why would they be dampened?

If this could exist, we would have the ability to do refrigeration without heat extraction and it would be great. But today, this appears to be impossible.

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Old 13th October 2020, 10:00 AM   #74
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Originally Posted by Ziggurat View Post
This is a bit off topic, but I wanted to give an example of this power, by showing how it answers a question without needing details.
I share your joy in the power of understanding thermodynamics.

Another aspect I enjoy is that it is not the science of the ivory tower, it is the science of the greasy elbow. These laws were not derived to win awards, they were derived to make machines work better. This is a field of science driven by the need of power.

For some reason that resonates in me even though I moved from mechanical engineering to civil after taking my basic thermo classes.
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Old 13th October 2020, 10:57 AM   #75
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Originally Posted by theprestige View Post
I don't see a level trough of water in the scenario I'm looking at. Let's move on from the analogy back to the thing itself:

I have a bunch of molecules (atoms?) bouncing around. I hook up a device such that when a molecule hits it, it generates some electricity. The bouncing of the atoms is necessarily dampened by this process. How is the generation of electricity not possible in this scenario?
You start with a piece of graphene at the same temperature as its surroundings. That is equivalent to a level trough of water at equal height on both ends. You are suggesting that we can put a ratchet on a water wheel and dip it into the trough, converting random motions of the water to motion of the water wheel while all the water flows to one side of the trough.

We don't run water wheels from water flowing uphill. If we want water to go uphill, we have to put work in to pump it there. If we want to cool something in the absence of sink at a lower temperature than what we want, we must put work in to cool it. You can't just extract energy from thermal motion.
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Old 13th October 2020, 11:06 AM   #76
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Originally Posted by BowlOfRed View Post
If this scheme could cool the graphene, we could then get work out of just letting it warm back up.
I don't see any problem with this. As I've been saying: As long as we keep adding heat to the graphene, we can keep getting work out of it.

To me, this doesn't seem any different in principle to adding pressure to water vapor to get work out of it.

Quote:
Although you might think of cold things having less energy, we can get work out of that state.
If you say so, but it seems like what you're really talking about is getting work out of things that are hot, and then adding more heat to them to get more work out of them.

Quote:
If we had something that could be kept cold forever, we would have a near perpetual energy machine, just by extracting work. We could create a heat "water wheel" and power it by letting the rest of the heat in the universe fall through it.
To be clear: I'm not at all interested in the perpetual part of the original claim. Just the mechanical part of using Brownian motion to generate electricity.

I know this must seem obvious to you. I apologize for being so obtuse. It really seems like you're coming to this with unstated assumptions about the system that aren't apparent to me.
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Old 13th October 2020, 11:09 AM   #77
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Originally Posted by BowlOfRed View Post
The waterwheel is exploiting a gradient. There is a difference between the moving water at the bottom of the wheel and the non-moving ground. The wheel can do work on this difference.

Take the wheel and disconnect it from the ground and put it underwater in the middle of a fast-moving river. There's lots of energy there, but without a gradient, the wheel cannot extract work from it.




The water wheel is moving the water to a lower potential energy and it might be slowing water to a lower kinetic energy. It has a place to lower water to, and it has a ground that it can slow the water relative to.



In a isothermal bath, there's no way to slow anything down to extract the energy. Your equipment must be just as hot, so your molecules are also moving quickly.
Where is the isothermal bath coming from? There's a sheet of graphene, connected to a switch of some kind. Molecules in the graphene impinge against the switch, triggering an electromechanical process (?).

What unstated assumptions do you need to state for my benefit, so that I understand the problem with this?
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Old 13th October 2020, 11:11 AM   #78
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Originally Posted by cjameshuff View Post
You start with a piece of graphene at the same temperature as its surroundings. That is equivalent to a level trough of water at equal height on both ends. You are suggesting that we can put a ratchet on a water wheel and dip it into the trough, converting random motions of the water to motion of the water wheel while all the water flows to one side of the trough.

We don't run water wheels from water flowing uphill. If we want water to go uphill, we have to put work in to pump it there. If we want to cool something in the absence of sink at a lower temperature than what we want, we must put work in to cool it. You can't just extract energy from thermal motion.
What if I start with a piece of graphene that is hotter than its surroundings?

You seem to be trying to address the perpetual motion part of the claim, which I explicitly rejected and flatly don't care about. I'm only interested in the basic electromechanical part of the claim.

Say I heat up a piece of graphene and connect it to this switch. Will the Brownian motion generate electricity while the graphene cools off?
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Old 13th October 2020, 11:12 AM   #79
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Originally Posted by theprestige View Post
I don't see any problem with this. As I've been saying: As long as we keep adding heat to the graphene, we can keep getting work out of it.

To me, this doesn't seem any different in principle to adding pressure to water vapor to get work out of it.
It takes work to pressurize water vapor, or any other gas. You don't need to do any work to let the graphene warm back up. In fact, you can do more work by using it as a cold sink for a heat engine with its "hot" side at ambient temperature.


Originally Posted by theprestige View Post
To be clear: I'm not at all interested in the perpetual part of the original claim. Just the mechanical part of using Brownian motion to generate electricity.
You can't separate the two.
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Old 13th October 2020, 11:13 AM   #80
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Originally Posted by theprestige View Post
You seem to be trying to address the perpetual motion part of the claim, which I explicitly rejected and flatly don't care about. I'm only interested in the basic electromechanical part of the claim.
What you are interested in is totally irrelevant. You don't get to pick and choose when and where physical laws apply based on what is interesting.

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