Researchers Re-Examine Second Law of Thermodynamics 125
Many readers have written to tell us that researchers are examining the possibility of using Brownian ratchets to help combat the problem of heat dissipation in miniaturized electronics. "Currently, devices are engineered to operate near thermal equilibrium, in accordance with the Second Law of Thermodynamics which states that heat tends to transfer from a hotter unit to a cooler one. However, using the concept of Brownian ratchets, which are systems that convert non-equilibrium energy to do useful work, the researchers hope to allow computers to operate at low power levels, and harness power dissipated by other functions. 'The main quest we have is to see if by departing from near-equilibrium operation, we can perform computation more efficiently,' Ghosh told iTnews. 'We aren't breaking the Second Law — that's not what we are claiming,' he said. 'We are simply re-examining its implications, as much of the established understanding of power dissipation is based on near-equilibrium operation.'"
Obligatory Simpsons: (Score:5, Funny)
Tag it... (Score:5, Funny)
Tag: weobeythelawsofthermodynamics
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Maybe there should be a department for that or something.
Obligatory Flanders & Swann quote (Score:3, Informative)
"Heat won't pass from a cooler to a hotter
You can try it if you like, but you'd far better notter"
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Stupid Flanders.
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D'oh!
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It will and can if you induce electricity into it and use specific dissimilar metals. This is known as the Peltier effect and while it technically moves the heat through the effects of the electrical charges, it does have the effect of moving heat from a cold metal to a hot metal in applications such as battery operated coolers and such.
Of course I didn't get the Flanders and Swann connection so I may be ruining a good joke.
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Hmmmm, help me out here. (Score:5, Informative)
I may just be too stupid to follow this, so feel free to slap me down.
The article sucks, obviously, but they repeat the phrase "Brownian Ratchet" incessantly, and I know what those are: a theoretical molecular machine able to extract energy from a heat source that is in thermal equilibrium. Obviously this would be interesting because normally we use heat transfer to generate energy and if there is no excess to transfer one would suppose (based on the second law) that there is no extra energy to be converted to whatever work needs to be done.
But the article and the summary both use the phrase "non-equilibrium" which suggests the existence of heat energy in excess of what is naturally dissipated, which is, gosh, the source of almost all the power that we use, in one form or another.
So either I'm unclear on the concept of a non-equilibrium thermodynamic state, or they don't know what the fuck a Brownian Ratchet is, and are trying to grab a sensationalist headline by making a wild claim that has nothing to do with what they're actually doing (e.g. running the system fans off steam power or something).
Re:Hmmmm, help me out here. (Score:4, Interesting)
Re:Hmmmm, help me out here. (Score:4, Interesting)
Well the idea of using the heat energy to do something is all well and good, but they would need something that actually needs to be done...Otherwise it would seem to be more efficient to simply strive for greater efficiency, and try to reduce the amount of waste heat.
Re:Hmmmm, help me out here. (Score:4, Insightful)
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Re:Hmmmm, help me out here. (Score:4, Interesting)
Well, it depends a little on exactly what they're doing. There was an argument that you couldn't use air cooling to go below ambient temperature. Let us say you've N chips, with some method of transferring the heat from all of them to a common point. The common point can now be air cooled to ambient temperature, which means that the N chips must be cooled below that. You generate heat by doing so (2nd Law) but so long as that generated heat is outside the airstream you're using, it won't affect the ambient temperature, except in a closed system, where this must necessarily break down almost immediately.
It would follow that if you could transfer heat from surrounding areas to a more concentrated region, you can get enough heat to do interesting things with. But it has to be concentrated, or you won't have enough to be able to do anything. You won't be able to do anything useful with a thermocouple, as you don't have any inherent cold regions and making one will cost more energy than the thermocouple could provide. So what else can you do with heat? Heat causes expansion - a really bad idea for any material using variable materials in layers to produce tracks - but there are possibilities for nanoscale mechanical systems. Not many, though, and nothing I can think of that would be useful.
Let us say you have N compute devices, but for some reason (due to prior threading, perhaps) the ones in use are highly concentrated together. The heat could be used to trigger a re-distribution of workload. Seems unlikely to be fast enough, but it's one possibility.
Option 2 would seem to be based on electron tunneling. This phenomena is deliberately used to create jumps between lines that you can't build physically on a 2D circuit except by using lots of very slow logic. Electron tunneling is partially a function of the medium. If you could therefore alter the medium sufficiently, you basically have a very slow but serviceable switch. This is only useful if there's anything so long-term that an extremely high latency switching mechanism would be useful.
Option 3 is where data is retained in the absence of power (for some time - doesn't matter how long) but you need it to act like volatile memory. Maybe you could use heat to zero the state of such memory. Again, it's very slow, so you'd need something that needed so much zeroing that doing the same operation electronically would be slower. This is possible because although heat has a very high latency, it diffuses well and therefore provides a massively parallel method.
Option 4 is to find the researchers and tie them by their feet to the top of the mast of a Tall Ship and leave them there until they do something worthwhile. I favour option 4.
Re:Hmmmm, help me out here. (Score:5, Informative)
Re:Hmmmm, help me out here. (Score:5, Interesting)
Re:Hmmmm, help me out here. (Score:5, Insightful)
Then i don't see why they re-examine the 2nd law.
As far as I can tell, they're not; this is YAIMSH (Yet Another Ignorant, Misleading Slashdot Headline)—something that occurs so often it really needs an acronym. :)
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Wouldn't YAMISH be a better acronym?
Re:YAMISH (Score:2)
All in favor, tag the article!
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something that occurs so often it really needs an acronym.
Stosoirnaa.
-
Re:Hmmmm, help me out here. (Score:5, Funny)
emerge maxwelld
/etc/init.d/maxwelld start
Done.
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USB-powered Brownian Ratchet (Score:2)
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a system in thermodynamic equilibrium can still have lots of energy. We use energy transfer as our means of capturing energy, Brownian ratchets could sit in a system that has thermal equilibrium and capture the energy found there by transferring the energy from particles that hit it.
Re:Hmmmm, help me out here. (Score:5, Informative)
I think Feynman's objection there was that, without a gradient, the system would lock up because an equal force would be exerting in both directions...Effectively a system that can be moved in one direction by equilibrium heat can necessarily be moved in the other direction as well, and therefore the net effect would end up being zero.
Re:Hmmmm, help me out here. (Score:5, Informative)
Exactly. Feynman showed that unless the ratchet itself is at a lower temperature/higher enthalpy/lower entropy than the surroundings, there's no way to extract the energy which sits in the heat reservoir. Once you've stuck that ratchet in there, in full thermodynamic contact with those surroundings, it's going to quickly heat up and its "ratcheting" action quickly become just as random as everything else.
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What if you could create a nano ratchet that can only go in one direction? This would allow you to get to Near perfect equilibrim.
Maybe it wouldn't be a ratchet per-se, but a tube that only lets Brownian motion escape in one direction. Like what a laser does with light.
Re:Hmmmm, help me out here. (Score:5, Informative)
What if you could create a nano ratchet that can only go in one direction?
It's an interesting question. That's what people thought ratchets were in the first place. Then Smoluchowski (1912), Callen and Welton (1951), and later Feynman (as popularizer, mainly) showed that once the ratchets come to the same temperature as the "working fluid" in which they're placed, the ratchets can no longer be one-way devices. In fact, for any ratchet above absolute zero, it will occasionally "miss" and slip backwards. In other words, people who want ratchets to consistently extract energy from a fluid have to keep the ratchets at absolute zero, which means they're not in equilibrium with the fluid.
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Already done [istockphoto.com].
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I may just be too stupid to follow this, so feel free to slap me down.
False humility does not become you sir.
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Obligatory Wikipedia reference (Score:5, Interesting)
You are correct.
As described by Feynman, a Brownian Ratchetis a theoretical machine that can extract energy form a system in equilibrium. It is a kind of Maxwell's demon [wikipedia.org].
Feynman explains why such a machine will not work without a potential energy gradient and is in fact a perpetual motion machine.
TFA seems to indicate that they intend to operate from a system not in equilibrium, which is allowed by the Thermodynamics Police. But it isn't very clear from the summary.
Re:Obligatory Wikipedia reference (Score:4, Informative)
You're right, but when a part of the chip is at a scorching 70C or more, I wouldn't really say that's really equilibrium.
The article (which *IS* a summary, btw) as I understand it, says: Let's use the excess heat in some parts of the chip and use that as a secondary power source.
In other words, it's not about breaking the 2nd law, but identifying the points of excess heat dissipation (read-as: Low efficiency) to minimize energy waste. I find that feasible, I read an article in physorg about using the excess heat in car exhausts to power up the electronics, for example.
Re:Obligatory Wikipedia reference (Score:4, Insightful)
Let's use the excess heat in some parts of the chip and use that as a secondary power source.
So ... maybe you could use the heat from your CPU to spin the HDD or something? That sounds possible and I guess it would make the system as a whole more efficient. The biggest problem is probably going to be cooling the CPU. It would seem to me that any sort of heat engine driven by heat from the cpu is going to impede the cooling of said CPU. And for that heat engine to be very efficient at all it's going to have to have a high temperature gradient. If the gradient is 75C to 22C it can only be 15% efficient (I think. It's been a while since I studied thermo.).
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Let's use the excess heat in some parts of the chip and use that as a secondary power source.
It would seem to me that any sort of heat engine driven by heat from the cpu is going to impede the cooling of said CPU.
Maybe not by dissipation, but turning the heat into kinetic energy, effectively cools the CPU. Otherwise we would be breaking the 2nd law by producing energy out of nothing.
Perhaps what you're trying to say is that if the efficiency of the device is pretty low, the heat won't be converted to electrical energy as fast as it accumulates. But think about this: What if the device used to collect the heat goes BETWEEN the CPU and the heat sink? By definition, the sink is ALWAYS cooler than the CPU, therefore making heat transfer possible. Actually that's the opposite of what peltiers do: They use electricity to accelerate the heat transfer from the CPU to the heat sink.
Here's an article about devices using excess heat [eurekalert.org]. Perhaps it's the same device discussed in this article since it's 3 months old, but I'd need to double-check.
Hmmm nope. Here's the original research page [virginia.edu] about THIS article. What's interesting is that the link doesn't mention anything about brownian rachets. In fact, there are NO articles there!
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I wish someone asked why it couldn't be used to power a nano-generator, since it wouldn't matter which way the paddle moved, thus as long as the shaft is moving in any direction.
Of course it couldn't be perfect. Only at perfection would it violate the second law.
Be careful quoting dead physicists becasue there opinion is based on the knowledge at that time and can not be updated or reconsidered by them.
Tiny weeny steam machine (Score:2)
TFA seems to indicate that they intend to operate from a system not in equilibrium, which is allowed by the Thermodynamics Police. But it isn't very clear from the summary.
Yep, that's what I understood too : they are going to build something conceptually close to a a steam (or other heat powered) machine, in order to take advantage of the differences in thermal equilibrium.
Except, without steam.
And much, much smaller.
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Not quite. Maxwell's demon operates in a system that is in equilibrium at a macroscopic scale but may have minor incidences of non-equilibrium at microscopic scale and using this micro-unbalanced state to encourage more non-equilibrium, eventually altering the large scale state to a macroscopic non-equilibrium. But taking advantage of the non-equilibrium state for power moves it towards equilibrium faster than it can move it away.
Attempts to harness energy from a non-equilibrium state tends to make the sta
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Great. Now I have a picture in my mind of Zippy [wikipedia.org] incessantly repeating "Brownian Ratchet, Brownian Ratchet, Brownian Ratchet".
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I remember seeing a Zippy comic strip taped to a door at the electronic arts building of my alma mater in 1990. It had him walking along, laughing, saying, "Satellite Uplink" repeatedly, similar to your post.
To what does this refer? I've been pondering it for 18 years.
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As you've observed, a recurring theme in the Zippy comic strip is for Zippy to simply repeat a phrase over and over again.
Zippy is easier to understand once you stop expecting it to make sense.
Linke's lab at UO. (Score:5, Informative)
One of my friends got her degree in Linke's lab: http://www.uoregon.edu/~linke/res_ratchet.html [uoregon.edu] . She was good at explaining the ratchets, and one of the things always stressed was that they don't work in thermal equilibrium---by definition!. In any case, Linke's website has good explanations.
It's not perpetual motion machine. It's a fan. (Score:4, Interesting)
One of my friends got her degree in Linke's lab: http://www.uoregon.edu/~linke/res_ratchet.html [uoregon.edu] .
If the front page at Linke's lab is related to whatever inspired the article: I bet they're trying to make a microscopic fan (with an external power source) as a linear motor, not a perpetual motion machine. They're not trying to scavenge the power from the heat. They're trying to move the hot molecules around.
Such a fan could be in the form of a structure of electrodes on the top of the chip which moves the coolant by creating intermittent sloped potential wells, using the brownian motion from the heat to accomplish part of the motion of the surrounding coolant.
You'd still be providing the energy to move the molecules when you create and then dissipate the potential wells. You make a "traench with a sloped bottom", the molecules fall into it and slide to one end, you raise the bottom of the hole, lifting them, and they scatter, with some of them ending up over the NEXT trench location next time. No free lunch - you provided the energy to move them by lifting them out of the potential well when you demolished it.
I suspect that they are using brownian ratchets for the motors, rather than trying to move the molecules directly, because they found a way to implement the former efficiently.
But I'd like to see how it works and what makes it better than creating a similar array of stepwise-moving potential wells ala charge-coupled devices. More efficient? Fewer drivers? Sloped potential wells easy to make using triangular or other interesting electrode shapes? Larger structures that can be fabricated at current semiconductor feature sizes?
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What I understanded is that they plan to create a thermal machine to help powering the chip, thus reducing power consuption and heat.
And, yes, the writter seems to have no idea of what a brownian ratchet is. I guess that "non-equilibrium brownian ratchet" is some kind of thermal machine that is somewhat similar to the brownian ratchet, and the researcher talked about it while explaining his research, what made the writter quite confused.
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What I understanded is that they plan to create a thermal machine to help powering the chip, thus reducing power consuption and heat.
So at what point does it become counter productive? "I'm using excess heat to generate power so that I reduce the amount of excess heat (which in turn generates less power from that heat --> etc.)".
Layne
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Use the excess heat to turn a fan to cool the chip. If there's not enough ehat to move the fan, then it's not hot enough to need to be cooled.
MSI is talking up using a Sterling engine to do just that. Engadget has a blurb about it. [engadget.com]
Re:Hmmmm, help me out here. (Score:5, Informative)
A "Brownian ratchet [wikipedia.org]" is a thought-device about extracting energy from the random Brownian motion of a hot gas. Similar to Maxwell's Demon [wikipedia.org], it can't work in a system at equilibrium. Without a temperature gradient, there is no way to extract useful work. The ratchet will be undergoing random motion equal in magnitude to the energy we hope to extract, so we can't actually extract anything.
However, if we're not at equilibrium, the rules are different. These researchers are talking about "non-equilibrium Brownian ratchets", which you could also call a "Brownian motor [wikipedia.org]". In an non-equilibrium situation, you will have a gradient of heat or chemical potential that could, in principle, be converted into useful work.
So my guess is the researchers are trying to do something like:
1. Build devices that exploit the temperature gradient that exists in the device. So a bunch of nano-sized ratchets that convert the heat gradient on the outside of the chip (relative to the cool air) to recharge a capacitor or something.
2. Build switching elements (e.g. transistors) that directly store the excess switching energy in some way. That is, build switching elements that both do computational switching, but immediately utilize the resulting temperature gradient of the dissipated heat.
In either case, all they are suggesting is to take advantage of the heat gradients that inherently occur when you have imperfect switching elements dissipating heat. It's not really that novel, conceptually... although if they actually have a specific way to do this in mind, then that could be quite interesting.
Re:Hmmmm, help me out here. (Score:5, Informative)
On his webpage, Ghosh has this to say [virginia.edu]:
(Emphasis added.)
So this seems like still very early work (just an idea, really)... and it appears that the intention is to build new kinds of switches (e.g. transistors) that exploit the fact that switching is inherently non-equilibrium, and extract some of the energy that is dissipated during these switching events.
Re:Hmmmm, help me out here. (Score:4, Informative)
The article is terrible. They're actually looking at non-equilibrium Brownian ratchets, which is very different from a Brownian ratchet. Much like how they're not reexamining the second law of thermodynamics, they're reexamining its implications.
As I read it, the general idea seems to be that instead of simply burning electricity and disposing of the waste heat, they're considering reclaiming some of the waste heat to help power the device (which could help reduce its heat output). Of course, since they're consuming energy to perform calculations (which are entropy-reducing), they're required to emit a certain amount of uncapturable heat.
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Reference: Brownian Ratchet [wikipedia.org]
The idea is that you could use a Brownian Ratchet within the context of a heated chip and nano-mechanical system to do work such as locally cooling the chip or charging capacitors... whatever... something useful (but exactly what we don't hear mentioned)... the article also doesn't mention it but they are probably talking about ratchets where the pawl assembly (T2 on the wikipedia picture) is small enough to enable energy to be extracted from the thermal gradient in accordance wit
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*LOL* just reread my post. It should say that the temperature at T2 near the ratchet an pawl assembly is small enough and the temperature T1 at the paddle assembly is large enough then the energy can be extracted... sorry... the physical size of the assemblies is not the critical factor.
I am not a physicist but I know one.
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I would guess the article is missing some point, typical. What they seem to be driving at is an accurate portrayal of the 'Brownian Ratchet'.
They key is creating a gear and pawl that isn't effected as much by Brownian motion is its surrounding enviroment.
A Brownian Ratchet could be used in both states., Yes we can get work from a non-equilibrium, this would be a different way of doing it. In fact, if you can get it to produces tine bits of electricity from waste heat, this would lead to cooler chips.
Now, if
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> Yes we can get work from a non-equilibrium, this would be a different way of doing it.
> In fact, if you can get it to produces tine bits of electricity from waste heat, this
> would lead to cooler chips.
No, it would lead to warmer chips. Forcing the heat to flow through a heat engine (which this gadget is) rather than directly to the sink inevitably means higher effective thermal resistance.
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"Brownian Ratchet" incessantly, and I know what those are: a theoretical molecular machine
I thought they were widely observed in microbial locomotion systems?
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As far as I understand it, they're basically saying:
Gee, why don't we, instead of work on cooling the system by exhausting the heat (thing CPU fan), try to convert the heat back into reusable energy.
For those who enjoy car analogies that can easily be refuted on a pedantic level, its like many hybrid cars makers who said:
Gee, why don't we, instead of wasting the kenetic energy when the vehicle brakes, try to convert it back into reusable energy.
Basically they're just challenging the old paradigm in electronics that you need to get the heat out of the system and instead suggest thinking of it as a possible energy source.
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A Brownian Ratchet is a thought experiment and has not been observed in the real world. I could do a thought experiment about suspending the law of gravity but the law of gravity would still apply in the real world. The article gives no specifics but strongly implies that someone has found a "loophole" in the Second Law of Thermodynamics.
"BraaaaaP!!!"
They're not breaking the law (Score:2)
RS
Very bad title, but par for the course (Score:2)
Wrong. Bad summary (Score:1, Redundant)
Statements like this make the physicist in me cry out in pain.
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It is often referred to as the 0th Law of Thermodynamics that states that thermal energy flows down a gradient. It pretty much defines what temperature means.
Care to explain? The best definition of temperature that i came across is m*v^2_{rms} = f*k_B*T
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The best definition of temperature that i came across is m*v^2_{rms} = f*k_B*T
You need the concept of temperature to use/derive this equation. For example Boltzmann's constant involves the concept.
And let's not forget it's gnu/rms.
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Hmm...I guess that does make sense. Next time: more think, less post.
Not much insight from the article (Score:3, Insightful)
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That's because that's the only place they've ever existed.
These guys are just using the word; they're not really clear on what it means. If they have a thermal gradient, Brownian Ratchets do not apply.
maxwell's demon (Score:4, Interesting)
maxwell's demon [wikipedia.org]
old, well-tread, philosophically and scientifically fruitless territory here
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In Germany, the topic is worth a dissertation (Theoretical Physics) <cyn>But alas, there never was remarkable progress in physics from there.</cyn>
link(pdf) [google.de]
And, yes, avoiding to google beyond the first page and beyond the level of first thought makes the territory much safer.
CC.
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Maxwell's demon showed the impossibility of creating a thermal disequilibrium without work.
The article summary explains that they're leveraging an existing thermal disequilibrium to do work.
I think the two are completely unrelated?
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Indeed, the wikipedia article on "brownian ratchets" explains their use in non-equilibrium situations:
If, on the other hand, T2 is smaller than T1, the ratchet can indeed ratchet forward. In this case, though, energy is extracted from the temperature gradient in agreement with the second law.
The Feynman ratchet model led to the similar concept of Brownian motors, nanomachines which can extract useful work not from thermal noise but from chemical potentials and other microscopic nonequilibrium sources, in co
Very weak on details (Score:4, Interesting)
What a crappy article. Subtracting the techno-babble, it sounds like they want to attach a thermocouple [wikipedia.org] or heat engine [wikipedia.org] to their chips, which has already been tried many times and found to be not worth the effort. Maybe they think they have a better method, but I sure couldn't tell from RTFA.
Reading between the lines (Score:4, Interesting)
Subtracting the techno-babble, it sounds like they want to attach a thermocouple [wikipedia.org] or heat engine [wikipedia.org] to their chips...
Almost. Reading between the lines, it appears that they want to attach thermocouples or heat engines *IN* their chips rather then to them. They appear to be talking about the heat in the individual transistors within chips, rather than the entire chip. From the article, it sounded like they were trying to reduce the heat from each individual transistor and use that heat in different ways.
Can it be done? I have no clue. Can 50,000 nano sized thermocouples be more more efficient than 1 small one? Again, no clue.
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I'd like to add that, just because it wasn't worth the effort, doesn't mean that it isn't worth the effort. For various reasons, energy usage grows much faster than performance in current transistor designs. There are some experimental designs which reduce this significantly, but they're still in the early lab / press release stage, and nowhere near being ready for production. Just shrinking the process isn't giving the kinds of benefits it used to, because it increases leakage, which increases waste hea
But Brownian Ratchets don't work? (Score:1, Interesting)
I'm not an expert and wikipedia isn't a great source but in the article on Brownian Ratchets it mentions that any machine small enough to move based on the Brownian motion of nearby matter would be subject to Brownian motion itself. So are they saying they have a way of making brownian ratchets work or are they just assuming they can use something that most people believe doesn't work?
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They don't work AT EQUILIBRIUM. They do work if the pawl mechanism is cooler than the heat bath the paddles are in (that is, non-equilibrium). The latter is what the researchers in the article propose and is well within the workings of the laws of thermodynamics so the headline is extremely deceptive. In the process of operation, the heat from the bath is transferred to the pawl and gear while doing useful work just like any thermal engine (but using a novel mechanism). The second law is not even in questio
Essentially (Score:1)
The biggest problem with Brownian Rachets (Score:1, Funny)
They only work with english-sized particles. You have to use an expensive adapter for metric particles.
Maxwell's Demon... (Score:5, Funny)
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Not so sure this helps (Score:5, Informative)
To get the questions out of the way, the Brownian ratchet at equilibrium has been shown not to work, exactly as we might expect from the laws of thermodynamics.
But that's not what they're talking about. They are hoping to use a Brownian ratchet at a temperature differential, which is a clever way to extract work from a temperature differential to be sure, but is fully in line with thermodynamics as we understand it today.
The difficulty I have with this is that the problem in electronics is dissipating the heat fast enough to avoid a meltdown. Extracting work from the differential actually slows the heat transfer down (acts as an insulator) and so would make the device run hotter. It is NOT a cooling solution.
Where it could be useful is in low power devices that typically run well under their heat tolerance with a passive heatsink. In that case, the device could be run hotter in exchange for 'recycling' some of the energy they consume to make them even lower power.
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Where it could be useful is in low power devices that typically run well under their heat tolerance with a passive heatsink. In that case, the device could be run hotter in exchange for 'recycling' some of the energy they consume to make them even lower power.
So, in principle this is like putting a Peltier device between a chip and heatsink and using the resulting energy?
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So, in principle this is like putting a Peltier device between a chip and heatsink and using the resulting energy?
Exactly. The only question is which is more efficient. I'm betting the Peltier is a lot easier to make.
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The difficulty I have with this is that the problem in electronics is dissipating the heat fast enough to avoid a meltdown. Extracting work from the differential actually slows the heat transfer down (acts as an insulator) and so would make the device run hotter. It is NOT a cooling solution.
If this Maxwellian device operates at lower temperatures, perhaps the heat not getting dissipated that fast is not really a problem?
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To get the questions out of the way, the Brownian ratchet at equilibrium has been shown not to work, exactly as we might expect from the laws of thermodynamics.
But that's not what they're talking about. They are hoping to use a Brownian ratchet at a temperature differential, which is a clever way to extract work from a temperature differential to be sure, but is fully in line with thermodynamics as we understand it today.
Perhaps I'm reading this wrong. How can having the ratchet at a temperature differential ("between different temperatures"? "in a gradient"?) be described as having it in thermodynamic equilibrium?
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That's the point, a deeper analysis shows that it cannot work unless it's at a temperature differential. The researchers in TFA state that it will NOT be at an equilibrium.
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1. More energy removal for a given temperature gradient. Hence more energy available for computation.
That's the part where the trouble comes in. If the temperature differential is made to do useful work, the heat engine must act as an insulator. That is, the engine's effective thermal conductivity must be lower than if the hot side and cold side were directly coupled without extracting work. This means that for a given dissipated energy, the chip must run HOTTER (that is, the temperature differential increases to compensate for the insulating effect of the engine) in order to reach an equilibrium between e
Excellent, encyclopedic overview: (Score:2)
PDF alert!
http://www.uoregon.edu/~linke/papers/Reimann97_PhysRep.pdf [uoregon.edu]
The Three Laws of Infernal Dynamics... (Score:4, Funny)
1) An object at rest is ALWAYS in the wrong place.
2) An object in motion is ALWAYS headed in the wrong direction.
3) The energy required to alter either state is NEVER enough to make it impossible but is ALWAYS more than you'd care to expend.
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Aha! These must be the underlying physical principles of Resistentialism [wikipedia.org]...
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Just read the guy's home page for explanation (Score:2, Interesting)
http://people.virginia.edu/~ag7rq/ [virginia.edu]
follow the link to "Second Law? You must be kidding..."
"FYI -- there is some sensational press out there that makes it sound like we're planning to break/have already broken the 2nd law of thermodynamics. This is, of course, absurd -- but I think it's imperative we set the record straight before everyone starts jumping all over us.
The context.... a colleague and I received funding to study non-equilibrium switching invoking a concept called 'Brownian Ratchets' that has been
Just a like heat powered ac (Score:2)
The Second Suggestion of Thermodynamics (Score:1)
Re: (Score:2)
So breaking the law is HIGHLY unlikely, but it's not an absolute in the sense of the speed of light or absolute zero.
Seems to me... (Score:1)
Re: (Score:2)
That's exactly the assumption their model is meant to test.
Scientists tend to look at an assumption and ask a question about it. They then evaluate the question, and if the question is testable they model or simulate an experiment. Then they evaluate the data generated by the simulated experiment. If that looks promising, they run an actual experiment. Then they interpret the results to determine whether they are compatible with the previously held belief.
Welcome to science. Have a nice stay.
Thought experiment. (Score:2)
It is a chilly January day. I start my computer doing a long, complex calculation. Tired of waiting I decide to take a walk around the block. It is freezing out. I head back in before I get frostbite. I put my frozen hands in the warm exhaust from my laptop CPU fan.
Bingo. Work extracted from waste heat. I just need some place colder to move the heat to.
My understanding of the Brownian Ratchet idea is that if both ends of the brownian ratchet device (that is to say the the collection end, which is
Why should I? (Score:1)
I wasn't around when they passed this second "law" of thermodynamics, I don't see why I should follow it!
Blatantly Incorrect Title (Score:1)
They would have to be talking about Brownian Rachets that produce energy in an equilibrium environment for the title to be correct.
"Researchers Re-Examine Second Law of Thermodynamics"
No they don't, at least not in that article!