Could Maxwell's Demon Exist in Nanoscale Systems?

Jun 24, 2009 By Lisa Zyga feature
Scientists have found that Maxwell’s demon, or a creature that can sometimes decrease the entropy of a system without performing work, could exist in nanoscale systems, although it would not violate any physical law. Image: Wikimedia Commons.

( -- Maxwell’s demon may be making a comeback. Physicists know that the demon, an imaginary creature that decreases the entropy of a system, cannot exist in macroscopic systems due to the energy it requires to perform its role. However, a recent study has shown that, on the nanoscale, Maxwell’s demon might be able to do its work with much less energy than previously thought due to tiny thermal fluctuations that occur in small systems.

In their study, physicists Raoul Dillenschneider and Eric Lutz of the University of Augsburg in Germany have proposed a model in which a nanoparticle that can exist in one of two energy states (i.e. a double-well potential) serves as an erasable one-bit memory. The particle’s memory state is zero if it’s in the left well, and one if it’s in the right well. By resetting the particle’s state to a chosen state (either one or zero, regardless of its initial state), the particle’s memory can be erased. The question that Dillenschneider and Lutz ask is exactly how much energy (in the form of heat) is required to complete the erasure process.

The same question was investigated by physicist Charles Bennett in 1982, when he showed that Maxwell’s demon, which had been puzzling scientists since 1867, cannot exist. In theory, the demon stands between two neighboring chambers of the same temperature. By opening and closing a door to allow hot particles to pass to one chamber and cold particles to the other, the demon seems to decrease the entropy of a system without performing any work, apparently violating the second law of thermodynamics.

But, as Bennett noted, the demon’s memory, which it uses to track the coordinates of each particle, must be reset to its initial state during every cycle. Erasing the demon’s memory requires energy, and increases entropy. Bennett calculated the minimum amount of heat energy required to erase one bit of information, which is known as Landauer’s bound. It turned out that the demon was generating more entropy by discarding information about the particles than it was eliminating by ushering the particles into hot and cold chambers.

One thing that Bennett’s analysis did not account for was thermal fluctuations, which are usually extremely small at large scales and easily discarded. However, these fluctuations become predominant in microscopic systems, and scientists have recently begun to recognize that the second law should be amended to account for these fluctuations.

In the current study, Dillenschneider and Lutz have accounted for the impact of tiny thermal fluctuations on memory erasure in their nanoparticle-based memory system. Through calculations and simulations, they’ve shown that the nanosystem can be erased with an amount of heat that is less than Landauer’s bound. The finding shows that the macroscopic formulation of Landauer’s principle does not hold on nanoscale systems, and should be generalized to include heat fluctuations in a way similar to the second law.

“Our research aims at describing the thermodynamic behavior of tiny (nanoscale) objects,” Lutz told “It is known that thermal fluctuations dominate at these length scales. However, our investigations showed that they can have observable consequences in nanomemories: information may be erased by dissipating less heat than required by Landauer's principle. Our second main contribution was to propose an experiment that may allow us to study these effects using single-particle devices. Landauer's principle, despite its fundamental importance as a link between thermodynamics and information theory, hasn't been investigated experimentally yet.”

The result also presents the possibility that Maxwell’s demon might not create as much entropy as it reduces, although the exact difference is still unknown. The scientists noted that large fluctuations are suppressed, even in nanoscale systems, in agreement with the macroscopic formulation of Landauer’s principle.

“If one defines Maxwell's demon as a creature being able to sometimes decrease the entropy of the system without performing any work, then one might conclude that Maxwell's demon is likely to exist in nanoscale systems,” Lutz said. “However, one needs to emphasize that such negative fluctuations are legitimate at the nanoscale, and are generally exponentially small as described by the fluctuation theorem. The latter can be regarded as a generalization of the second law to small systems. So the existence of a nanoscale demon would not violate any physical law.”

Due to difficulties in tracking individual particles, Landauer’s principle has never been experimentally verified. But the scientists hope that recent progress in single molecule experiments could make testing possible. For example, an electrophoretic force (an electric force on particles in a fluid) could be used for controlling single particles, and a high-sensitivity CCD camera used to observe particles hopping between two wells. Lutz added that, since this research provides insight into nanoscale systems, it could have applications in other areas.

“Landauer's principle plays a fundamental role in information theory,” he said. “Our study was so far restricted to classical systems. The influence of both thermal and quantum fluctuations on memory erasure might have important consequences for quantum information processing as well (that is, erasure of qubits of information instead of classical bits).”

More information: Raoul Dillenschneider and Eric Lutz. “Memory Erasure in Small Systems.” Physical Review Letters, 102, 210601 (2009).

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User comments : 30

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5 / 5 (1) Jun 24, 2009
Odd. Why would the "demon" need any memory whatsoever, when all it needs to do is sense an approaching particle when it's near the door, and then open or shut the door depending on how fast the particle is approaching...

If the particles were charged, the sensing could be as trivial as just sampling the electric field...

Besides, I wonder if it shouldn't be possible to let the particles sort themselves, by introducing some sort of a patterned barrier that deflects fast particles differently than slow ones (analogous to a prism acting on different wavelengths of light...)
2.3 / 5 (3) Jun 24, 2009
To PinkElephant:

I also have not previously heard of a memory requirement for the demon but I think I can guess the answer. There must be a finite interval between the time an approaching particle's velocity is measured and the moment that the door must be either open or closed for it. One bit for either open or closed should suffice. After the particle is either passed or blocked the contents of that bit of storage is erased by being overwritten by the value for the next particle.

The patterned barrier/prism idea won't work because the particles are not in a beam but come from random directions over the solid angle subtended by a hemisphere.

1.8 / 5 (5) Jun 24, 2009
Maxwell had not been informed by Lee de Forrest concerning the movements of "Free Electrons". The static charge of the "free electron" preceeds it and repels blocking electrons to "open a door".
3.4 / 5 (5) Jun 24, 2009
"I invented a nanoscale Maxwell's demon. I don't have the time to model it on a computer. If anyone wants to talk about modeling it"

No you didn't Neil. This is another example of your spam lies.
Just like all your false cold-fusion, genetics, medical and nanotech claims.
not rated yet Jun 25, 2009
You guys are nerds....

wait what?
1.1 / 5 (8) Jun 25, 2009
Correct me if I'm off base here:

This could mean it operates like a gate or a puzzle lock. Quantum state set by variables like -e, spin, direction, etc... Depending on how the Gate was last "set" by those conditions would determine it's effect on the given volume either increasing or decreasing by the state of the particle moving in to the volume.
1.6 / 5 (7) Jun 25, 2009
A Maxwell Demon needs energy for his work. Therfore no MD has been found.

My GRAVITY Fairy seperates fast from slow molecules in any gravity field, just by existing. She creates temperature differences as described in

which can be used to create work, decreasing entropy.
1 / 5 (7) Jun 25, 2009
GF. What if it takes more than that? Charge, spin, Gravity/mass, direction... Fitting through a gate, or not, and modifying the net equilibrium in a given system.

Wouldn't require any more additional energy than a round hole. Round objects go through, square ones don't.
not rated yet Jun 25, 2009
Sounds like a particle statistics thing. The demon only opens the door for some particles or at some points in time, where/when the mentioned fluctuations take place. If you 'demonize' all the particles in a system, at any scale, ye olde laws should still hold, since those fluctuations probably go the other way around, too.
gravityfairy: ...Seriously? I find it hard to believe you've actually read those books in the literature section of your site. That is, the ones not written by you.
not rated yet Jun 25, 2009
If you can get the demon to step onto the nanoscale you are halfway there! But keeping it from breaking the law is a big stretch as we all know.
5 / 5 (1) Jun 25, 2009
A Maxwell Demon needs energy for his work. Therefore no MD has been found.

I think this is like the problem, why you can't take a ship and have it extract heat from the cold water of the sea rendering the sea-water colder while using the extracted heat to make it navigate. This nanoscale thing may give hope on just doing this on nanoscale. If you do it a billion times in parallel you may get some macroscopic effect.
I fear it is still in violation with thermodynamics and as such impossible to achieve.
not rated yet Jun 26, 2009
Yes, might I get your opinion?

Consider a material that always stayed "cold" or was at least always colder than its surroundings.

The surroundings would constantly give up heat energy to the cooler object which could be directly converted into electricity by the same object.

I guess the question is: is it possible for 100% efficiency in the conversion of heat to electricity?

"Irreversible systems and losses of heat (for example, due to friction) prevent the ideal from taking place at every step."

Right, but if you don't lose heat, you don't have to worry about going in reversible to get to where you started because you stayed neutral in your starting spot.

I believe Maxwell's demon to be of similar case.
1 / 5 (5) Jun 26, 2009

Yes, I read the listed literature. Did you? I propose that you study

3. Loschmidt, L., Ueber den Zustand des Waermegleichgewichts eines Systems von Koerpern mit Ruecksicht auf die Schwerkraft, Sitzungsberichte der Mathematisch-Naturwissenschaftl. Klasse der Kaiserlichen Akademie der Wissenschaften 73.2 (1876), p. 135

Here, Loschmidt proposed to Maxwell and especially Boltzmann that collumns of molecules or atoms should show in isolated systems under the influence of gravity a temperature gradient cold at the top and warm at the bottom. He could not convince them but felt that only experiments, not possible at that time, could decide this dispute.

My experiments confirm Loschmidt's ideas. I hope to find a university to repeat my experiments. I am happy to provide one of my gravity machines for this purpose.

not rated yet Jun 27, 2009
WW1 pilots having to wear warm clothing confirms his idea. That's not what I'm criticising. You claim to have found a source of cheap, renewable energy. I'm fine with that, too, it's not that unbelievable. Heck, I've toyed with the idea of extracting energy from naturally occuring temperature gradients myself, and I'm pretty sure it's not such a novel idea. It's the fact that you're claiming to have created a perpetuum mobile and thus disproved a fundamental law of physics, that's what ticked me off.
See, what I think happened is that you realised your source of 'free' energy is rather inefficient and not very marketable, so you decided to make it into a groundbreaking discovery in physics.
But, hey, that's my theory. Feel free to disprove it by publishing in a peer-reviewed journal, or convincing a university to test your invention. I take it you're just starting to do this now and you're hoping reputable scientists spend lots of time reading comment threads?

1 / 5 (5) Jun 27, 2009
Hallo, KASEN:

The cold temperatures at higher levels in our atmosphere have a different course than the the temperature gradients in my experiments. They are coursed by the influence of the sun, creating temperature differences and vertical air movements.

Yes, I claim I found renewable energy, not "cheap" energy.

I am not aware of any fundamental law of Physics which disallows the possibility of a Perpetuum Mobile of the Second Kind creating work out of a heat bath through the influence of gravity.

1 / 5 (2) Jun 27, 2009
1. Gravity affects pressure. Pressure affects temperature(and vice versa). The sun provides the energy, but it's not the sole factor, and if you were to calculate the temperature/pressure of a column of air based solely on incident solar radiation, you'd probably come a bit short(thus proving that air is heavy; yay!). However, do the same on a planet which hasn't received any external energy for quite a while, and you'll find there's no gradient to speak of. I do believe you're also contradicting yourself: http://www.firstg...nt.phtml .
Speaking of the sun, the birth of a star is another example of how gravity creates heat and temperature gradients. The point is, you can't extract energy from these without obeying...
3. ...the Second Law of Thermodynamics. Stars burn out eventually. Your 'gravity machine' should also only run for only a set period of time. By the way, how long has it been running?
As for 2, just what is the output of your invention and how much does it cost, in terms of space occupied and money invested?
5 / 5 (1) Jun 28, 2009
Sometimes I wonder why crackpots bother commenting, or even expecting those who know better to be conned, then I remember it is because they are crackpots.
1 / 5 (5) Jun 28, 2009
Hallo, Kasen:

Lets stay within the topic of this collumn, which is the Maxwell Demon and the Second Law.

1. The Second Law and Maxwell Demon apply only to isolated systems,no transfer of energy or mass across the boundary. I work with isolated systems. So, lets forget the influence of the sun.

3. You can find on my website the length of my experiments I am reporting about. Being in an isolated system they should run as long as the gravity field remains the same.

2. My websit gives measurements, you can estimate the costs connected with it.

not rated yet Jun 28, 2009
Thought experiments are the downfall of physics...
not rated yet Jun 28, 2009
Thought experiments are the downfall of physics...

Dontcha wish Einstein knew that...
1 / 5 (2) Jun 29, 2009
As it turns out, regular experiments can lead to the same.

I'm not sure how heat insulation is done in actual experiments, but I doubt it's with commercially available thermos bottles. Furthermore, consider this. You're using extremely sensitive thermocouples. To say something related to the article above, fluctuations can occur at high resolutions, and that's what I can tell from that first graph on your site(which, oddly enough, leads to the second one, when clicked on for zooming purposes). It's only when you average them out, in the second graph(how odd!), that you come up with something that seems to confirm your theory, and even then, it's such a small value, and in such a small space(I guess they don't sell thermos bottles bigger than 50 cm), that it could easily be discarded as measurement error. Oh, and for all the details you give on you home-made-space-grade thermal insulation, I can't seem to find any information on electrical or mechanical shielding. The electrical bit should be quite interesting, since you've decided to shield your experiment in 5 cm thick copper panels. Also, I'm no expert, but fine PET powder sounds like something that could develop a hell of a static charge.
Look, I've said this before, you won't gain anything from trying to convince me, or anyone on comment threads, or on the Internet in general, except a few more hits on your site and maybe someone buying your BOOK just to prove you wrong. Come to think of it, it sounds like an easy way to make money.
1 / 5 (6) Jun 29, 2009
You guys are nerds....
I'll show you what i can do with software.

wait what?

You guys are nerds....

wait what?

1 / 5 (7) Jun 29, 2009
I'm not joking. I invented a nanoscale system of separating fast molecules from slow ones.

If you have software to model the process contact me at
3 / 5 (4) Jun 30, 2009
I'm not joking.
Pity, because you're the funniest clown in this circus.
1.6 / 5 (7) Jun 30, 2009
Neil, something that MAY exist in your head is not an invention. If you need someone to model the process for you than you neither have an actual invention nor do you have a clue as how to make what you claim to have invented.

Do you find this sort of nonsense entertaining? Or do you really believe that totally unverified and untested wild assed guesses, with no actual prototype, in some way actually resembles an invention.

Make something. Test it. Patent it.



Quantum Physicist, torturer of AGW religious zealots like Ethelred because i laugh at his hysterics.

QubitTroll will be released from my sig at the end of June.
1 / 5 (7) Jul 01, 2009
Don't tell me what to do or how to conduct my business. Every experiment, every hypothesis, and every invention must be conceived in a person's mind before it is reduced to practice or proved. You have no idea how far I have come in developing my concepts. Some of them are close to being patented. I patented a surgical adhesive that sticks to wet oral and vaginal mucosa. It might be used to hold Tampax in place. There are pictures of it on my website. Its real all ready.
1.6 / 5 (7) Jul 01, 2009
Don't tell me what to do or how to conduct my business.

Then don't push it here. As long as you do you will get pushback.

Every experiment, every hypothesis, and every invention must be conceived in a person's mind before it is reduced to practice or proved.

And has no meaning until proved.

You have no idea how far I have come in developing my concepts.

Not my fault.

Some of them are close to being patented.

Good. Good luck with them.

I patented a surgical adhesive that sticks to wet oral and vaginal mucosa.

I mentioned that.

It might be used to hold Tampax in place.

There are already ways to do that and they don't require expensive nano-tubes.

From your site:

Contains 99.99% carbon nanotubes manufactured by Vulvox's proprietary patent pending process

I note that your site says the patent is still pending.

For experimental research. Not approved for medical or veterinary uses.

Which is one thing I was getting at.

$ 500 per gram, up to 10 grams.

That is so going to be used for Tampax. Yes I know that the price will come down IF you get enough buyers. The nano-tubes will still be to expensive for use until someone figures out a way to make them a lot cheaper.

And your site is still ugly. Get rid of the dark blue at least. Dark blue on white works much better is you insist on using the dark blue.

You can take that badly or you can consider it constructive criticism. I don't much care which.

2.3 / 5 (3) Jul 01, 2009
Don't tell me what to do or how to conduct my business. Every experiment, every hypothesis, and every invention must be conceived in a person's mind before it is reduced to practice or proved. You have no idea how far I have come in developing my concepts. Some of them are close to being patented. I patented a surgical adhesive that sticks to wet oral and vaginal mucosa. It might be used to hold Tampax in place. There are pictures of it on my website. Its real all ready.

Neil, your butt-glue has no use whatsoever. You have discovered nothing, merely observed that something sticky sticks to something sticky.

... and why were you shoving nanogoo up your bum? ... on second thought, don't answer that.
1 / 5 (7) Jul 07, 2009
All of the normal people are bothered by your obscene
language NON.
1.6 / 5 (7) Jul 08, 2009
Blue and white work together quite well. I have no desire to change the website.

Blue ON white works together. But go ahead, leave it ugly. It is only you that is harmed. I suppose you could have done worse. Red and blue for instance. Then it wouldn't matter which was the text.

This reply shows you haven't a clue about what is ugly. You did not need to copy the whole post to reply to it.

As far as the carbon nanotube adhesive goes.. we will soon have data on several of its characterized properties from a partner laboratory.

Good. But that won't fix the cost. Nano-tubes will only be lab tools unless the cost comes down.