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Researchers Re-Examine Second Law of Thermodynamics
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.'"
"Young lady, in this house we obey the laws of thermodynamics!"
Monstar L
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).
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
RS
Shoes for Industry. Shoes for the Dead.
They very specifically say they are not even challenging SLOT. But the title is grandiose. Well, I am reexamining Djikstra's dictum, "Always debug code, not the comments."
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
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. The Second Law does not involve systems in equilibrium.
Statements like this make the physicist in me cry out in pain.
Tag: weobeythelawsofthermodynamics
Can anyone explain what they're doing/hope to do? The only time I've encountered the phrase 'Brownian ratchet' was Feynmans example of a Maxwells demon which turns out not to work.
"Physics is to math as sex is to masturbation." -R. Feynman
Then that would be a nice thing to invoke right now.
the relevant bit:
"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.
âoeThe main quest we have is to see if by departing from near-equilibrium operation, we can perform computation more efficiently,â Ghosh told iTnews.
âoeWe aren't breaking the Second Law -- that's not what we are claiming,â he said. âoeWe are simply re-examining its implications, as much of the established understanding of power dissipation is based on near-equilibrium operation.â
But while the physics of non-equilibrium Brownian ratchets has been studied extensively for some time, the conceptâ(TM)s application in a technology context has not.
Ghosh expects to face challenges ranging from proof-of-concept demonstration, to going beyond models to experimental testing, and analysing the practicality, robustness and cost-effectiveness of these schemes.
âoeUntil we do a proper study, we can't be sure whether this method would suffice
to address the considerable challenges of heat generation and removal,â he said.
âoeOur short-term plan is to study this over the next three to five years at this time to see where we end up with non-equilibrium switching, and whether it could offer a solution.â
I don't need the karma :)
maxwell's demon
old, well-tread, philosophically and scientifically fruitless territory here
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
What a crappy article. Subtracting the techno-babble, it sounds like they want to attach a thermocouple or heat engine 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.
They'll disconnect the heatsink so the processor gets really hot. These higher temperatures can be more easily used to generate electricity. Then when the temperature drops to the point where electricity can't be easily generated any more, they'll put the heatsink back on.
There, you don't need to bite Newton to explain it after all.
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?
I'm afraid you're wrong too. The zeroth law gives us the idea of thermal equilibrium - what it means for systems to have the *same* temperature - but is mute on what it means to have different temperature. It is the second law that makes it meaningful to speak about `hot' versus `cold'. I guess the physicist in you must be pretty masochistic :-).
What they propose to do is use heat to generate work. By using this heat, they would essentially be cooling the device. All that stuff about Brownian motion (essentially molecular collisions) is only relevant when the device is miniaturized to the molecular scale.
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.
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.
Have gnu, will travel.
Subtracting the techno-babble, it sounds like they want to attach a thermocouple or heat engine 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.
Great civilizations have lived and died on false theories. Don't mess up mine with a few facts.
They only work with english-sized particles. You have to use an expensive adapter for metric particles.
One of my friends got her degree in Linke's lab: http://www.uoregon.edu/~linke/res_ratchet.html . 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.
My prediction: On *nix systems, a brownian ratchet power saving mechanism will be referred to as "Maxwells's Daemon". On NT based systems, it will be referred to as "Maxwell's Service".
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.
PDF alert!
http://www.uoregon.edu/~linke/papers/Reimann97_PhysRep.pdf
This will be helpful when I have a flat tire and don't have the air compressor and pneumatic ratchet handy to get the lug nuts off. Just, plug in a Brownian ratchet via USB into my laptop and zip off those lug nuts!!
It's true that school was a long time ago, so I may in fact be incorrect. Aren't thermal equilibrium and temperature inextricably linked? The 2nd law does speak to this, though, in that if you bring two systems together not in thermal equilibrium, they will tend towards it because the state in which they're in equilibrium has more entropy.
Hmm...I guess that does make sense. Next time: more think, less post.
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.
I am my own gestalt.
Now, if they'd said they were going to incorporate a Peltier device on the chip die to let 'em run heavily overclocked and ice-cold, I might've fallen for it . . .
http://people.virginia.edu/~ag7rq/
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 well studied in nonequilibrium statistical physics over the years. The potential benefactor of this study is the chip industry, in a very broad way, as it is worried about rapidly increasing thermal budgets (chips are becoming very hot). We're simply trying to examine the physics of Brownian ratchets in a device context. A popular model for heat dissipation in binary switching (proposed by Victor Zhirnov and co-workers) looks at a two well one barrier geometry, with a gate controlling the barrier and a drain controlling the overall directionality. Each such raising and lowering of a barrier at the end dissipates energy irreversibly (during the reset step where one erases information), leading to a kTln2 dissipation per operation (kT is the thermal energy). And this analysis is usually done by assuming that you wait after you raise or lower a barrier and then let the electrons move and reach equilibrium with the surroundings. The analysis is thus based on equilibrium Boltzmann statistics -- since the electron was at equilibrium before a computation and reaches equilibrium after. What is not clear is what happens during the non-equilibrium transition phase, or if you switch before the equilibrium is reached. The aim of the study is not to attempt to deviate from cherished physical principles, but on the contrary to see what these cherished principles posit for such a situation. A ratchet is known to be able to rectify non-equilibrium noise to produce directed motion by transducing spatial asymmetries in the system (this is well recognized in nonequilibrium statistical mechanics and has been mulled over for years). The physics is well studied, but the context is perhaps new... we are interested in seeing if rectifying such non-equilibrium noise (as a ratchet does) can perhaps shave off some of the power dissipation limit associated with a drain bias in the regular example.
This is, of course, still at a toy model -- we need to worry about how to deal with compatibility of input and output, for example. Simply put, we don't know if this will bear fruit for the big picture of low-power device operation, but it's worth investigating.
That's about it... but then, cooling laptops as hot as the sun through the power of thinking or by breaking the 2nd law sounds fancier ... doesn't it? "
He's talking about studying the transient state of electrons switching in a semiconductor barrier, and how it may be useful in reduce semiconductor heating.
"Heat won't pass from a cooler to a hotter
You can try it if you like, but you'd far better notter"
fiMrst post
Usenet posts. FreeBSD continues AND THE BOTTOM list of other I THOUGHT IT WAS MY itself ba3kwards, To decl1ne for Posts. Therefore become an unwanted need to scream that And she ran The mobo blew Mr. Raymond's antibacterial soap. one or the other to yet another cans can become one common goal -
What. The. Fuck.
...is declared to be a settled issue upon which no further debate is necessary and immediate action is needed to SAVE THE WORLD!!!
Pffft.
If I had a buck for every time I've carried my umbrella into work because the weatherman said that storms were coming in the afternoon only to tote it back to the car at the end of the day across a bone-dry parking lot, I'd have quite a few dollars. They can't predict the weather with any reliability 9 HOURS into the future, but we're supposed to panic because they've ascertained with irrefutable accuracy that the Earth will stifle in 50 YEARS unless we control ManBearPig NOW.
Uh, no.
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
When natural gas was cheap, many people had air conditioners that used the heat from burning natural gas to run the fluid portion (not the fans) of an air conditioner. My guess is this idea is similar in principle but on a much smaller scale of course. See http://www.gasairconditioning.org/robur_how_it_works.htm for an example of how this works. Sort of counter intuitive at first glance.
Okay, so I understand that everything about this article is actually in-line with the SLOT - or at least so far as we understand the article. But on a slightly separate note, if somebody comes up with some way to exploit the fact that the Second Law is actually a statement of probability and not a fundamental law, is it really breaking the "law" or is it just stacking the deck?
It would be more fruitful to try not to generate as much heat in the first place...
I still cannot find the droids I am looking for...
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 a paddle on a spindle, and the ratchet and pawl end, where the work is extracted) are at the same temperature, it won't work. If the energy collection end is hotter than the ratchet and pawl mechanism, then extracting work doesn't violate thermodynamics. It's just like me warming my hands: you have a place to dump the heat.
If you think about how we cool chips, we integrate the heat over large volumes and relatively long times. We take the waste heat from millions of transistors flipping millions of nanoseconds and dump it into the chip packaging and ultimately a big hunk of aluminum.
So -- and this is a big piece of conjecture from very little information -- perhaps the idea is to stick the paddle on or close to the transistor, and the ratchet and pawl mechanism onto the packaging/heat sink. Extracting work from the ratchet no longer violates thermodynamics because we have a heat gradient -- it's just a transient one over microscopic distance scales. We just grab a pico joule here and there of energy from spikes in waste heat from a particular semiconductor junction. On the macroscopic scale, we still have a big piece of aluminum in thermal equilibrium, but somehow the piece of aluminum isn't getting quite as hot.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
One of my friends got her degree in Linke's lab: http://www.uoregon.edu/~linke/res_ratchet.html .
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?
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
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.
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
All in favor, tag the article!
- "History shows again and again how nature points out the folly of men" -- Blue Oyster Cult, 'Godzilla'
I wasn't around when they passed this second "law" of thermodynamics, I don't see why I should follow it!
Nemateleotris magnifica
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.
Escher was the first MC and Giger invented the HR department.
may be all the thermodynamics dudes are old or dead ...
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!
Aren't thermal equilibrium and temperature inextricably linked?
Yes, in the sense that `temperature' requires thermal equilibrium. However, the existence of `thermal equilibrium' says nothing about the nature of temperature.
The zeroth law says that, if system A is in thermal equilibrium with system B, and B is in thermal equilibrium with C, then A will be in thermal equilibrium with C. That is, we can assign a common attribute to A, B, and C that says that they will be in thermal equilibrium, and any two systems with the same value of this attribute will be in thermal equilibrium. However, there is nothing in the zeroth law that guarantees that this attribute can be represented by a single number. Try replacing `in thermal equilibrium with' by `spatially coincident with' in the above statement, and note that the attribute `spatial location' cannot be adequately characterized by a single number.
The second law, however, asserts that, when comparing two systems with different values for their thermal equilibrium attribute, one can be identified as `hotter' and the other as `colder', in the sense that heat will always flow from the hotter to the colder. A Gedankenexperiment further shows that, if A is hotter than B, and B is hotter than C, then A is hotter than C. This property - that thermal equilibrium states form a completely ordered set - is what tells us that a single, real number is adequate to characterise `temperature'.
why not just AMISH? they'll never find out, it's on a computer.
(1.21 gigawatts) / (88 miles per hour) = 30 757 874 newtons
OhioU. Prof Hicks taught Thermoignoramics in the 1950s-80s.
This writer is confused on "2nd Law".
0-th ~= Energy goes from high to low. (There exists Temperature and equilibrium.)
1-st ~= Can't get something for nothing. (Energy is not created nor destroyed, just form changes.)
2-nd ~= Can't even break even. (Energy is dissipated as Entropy.)
See: http://en.wikipedia.org/wiki/Zeroth_law_of_thermodynamics