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Maxwell's Demon Soon A Reality?

Zonk posted more than 7 years ago | from the chomp-chomp-evil-snacking dept.

Biotech 148

DMiax writes "Reuters reports that a group of scientists from University of Edimburgh may have realized a nanomolecular engine - a Maxwell's Demon. The device selects and traps other molecules based on their direction of motion. Physicist James Maxwell first imagined the nano-scale device in 1867, and the research team cites him as the basis for their understanding of how lights, heat, and molecules interact. The device is powered by light, and may spur advances in nano-scale technology to new heights in coming years."

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148 comments

Possible to make unlimited energy? (3, Informative)

UbuntuDupe (970646) | more than 7 years ago | (#17850228)

The Wikipedia article [wikipedia.org] goes to great lengths to explain how the demon can't violate the 2nd law -- that it must delete information, which increases entropy. Okay. But what keeps it from violating the 1st law: that energy is conserved?

Re:Possible to make unlimited energy? (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#17850310)

I'm going to mod you. And post in the thread too. Offtopic I think. I love this bug in slashdot.

Re:Possible to make unlimited energy? (4, Interesting)

Control Group (105494) | more than 7 years ago | (#17850328)

Because the demon isn't increasing the energy of the system, it's simply sorting it. The total heat of the system doesn't change, it just goes from equilibrium to a gradient. The demon isn't conceptually picking out molecules and throwing them, it's deciding which molecules to let pass based on velocity. The energy is all in the molecules already.

Re:Possible to make unlimited energy? (4, Informative)

Stile 65 (722451) | more than 7 years ago | (#17850706)

You're correct, but creating and keeping a gradient also requires energy. That energy is given to the rotaxane molecules in the form of photons.

Re:Possible to make unlimited energy? (3, Insightful)

Stile 65 (722451) | more than 7 years ago | (#17850802)

Sorry, better reference is here [nanowerk.com] .

Article (3, Interesting)

Mark_MF-WN (678030) | more than 7 years ago | (#17853434)

Yeah, the title of this article is horribly misleading. This device is exactly the opposite of Maxwell's Demon -- it consumes energy and increases entropy. Maxwell's demon reduces entropy and can generate energy.


Obviously, the article irresistably leads to a discussion of Maxwell's Demon, and how this machine highlights the thermodynamic principles that were uncovered during the examination of that wonderfully subtle and insightful thought experiment. But it definitely doesn't mean that Maxwell's Demon may be a reality than machines that exploit relativistic effects suggest that we'll be able to ride around on beams of light, as in Einstein's thought experiment. Or that we'll be able to create superpositions of alive cats and dead cats (the hot new Valentine's gift for 2007 -- all the furriness and half the upkeep!)

Re:Possible to make unlimited energy? (1)

Anonymous Coward | more than 7 years ago | (#17850332)

Because it doesn't ever make more energy? I mean you could extract some energy with the heat differential... but as the article says it takes energy to measure the speed of the particles and open and close the gate. You might be able to increase the potential energy of a gas slightly but it is really just using the energy more efficiently, not making more.

Re:Possible to make unlimited energy? (1)

eklitzke (873155) | more than 7 years ago | (#17851492)

This is a result of Gauss' law, which is a standard result in vector calculus. This is a mathematical proof about continuously differentiable vector fields. If you took vector calculus in college you probably proved it. For the potential to not be differentiable would be _really_ degenerate case, which IIRC you just assume doesn't happen because there are standard formulas for different potentials (e.g. electric potential, gravitational potential) and all of them are well behaved.

Re:Possible to make unlimited energy? (2, Funny)

UbuntuDupe (970646) | more than 7 years ago | (#17851590)

Good point. Yours *is* pretty big.

Now, as for my question, did you have a relevant comment to add?

Re:Possible to make unlimited energy? (2, Informative)

Dilaudid (574715) | more than 7 years ago | (#17852140)

The reason the wiki article goes on about the second law (entropy increases) is because the first law (energy is conserved) is seen as being fairly obvious, e.g. a ball will never bounce higher than the level it was dropped from, and the first law applies both forwards and backwards in time. The second law is weird, since it is time inhomogeneous (entropy increases when time goes forward, and therefore would decrease as time goes backwards), and it seems to be more a statistical result than a scientific one.

It's interesting to note that the first law, conservation of energy, is not true within General Relativity within any bounded region, due to the existence of gravitational waves. Here's an article about it http://math.ucr.edu/home/baez/physics/Relativity/G R/energy_gr.html/ [ucr.edu] . I provide only this as evidence that I'm not talking out of my arse - I could understand GR once, many years ago, but not now.

It's neat, but it's not Maxwell's Demon (5, Informative)

Control Group (105494) | more than 7 years ago | (#17850258)

Maxwell's Demon was a thought experiment about the possibility of violating the second law of thermodynamics, not a thought experiment about sorting molecules. The idea was that the entropy of the system could be decreased by the demon selectively moving fast molecules from one side of the box to the other, thereby concentrating heat.

This tech is certainly a mechanism for such sorting, but it's powered by external light, so the entropy of the system has not decreased and the second law isn't violated. So, while it's mechanically similar to Maxwell's Demon, it's dissimilar in concept (or should I say, "in spirit" - we're talking about demons, after all).

Of course, TFA doesn't have Leigh claiming that they've come up with Maxwell's Demon, just that he "credits Maxwell for establishing the fundamentals for understanding how light, heat and molecules behave."

None of this is to say that this isn't an impressive feat, and of obvious value in terms of furthering the science/technology of nanomachines, but calling it Maxwell's Demon is missing the whole point of the original thought experiment.

[this text added to waste time between hitting reply and submit]

Re:It's neat, but it's not Maxwell's Demon (1)

mattjb0010 (724744) | more than 7 years ago | (#17850356)

... and the original though experiment said nothing about nanotechnology, either (maybe only in implication).

You're right, the naming is all wrong (2, Funny)

CrazyJim1 (809850) | more than 7 years ago | (#17851126)

This catches molecules instead of sorting them. It should be called Maxwell's cup.

Light coming in? (1, Insightful)

DarthChris (960471) | more than 7 years ago | (#17850282)

I may be wrong in this, since I haven't studied thermodynamics since I was doing my A-Levels, but I believe that the light coming in and powering it directly violates the setup for Maxwell's Demon. Can someone confirm or deny this?

Re:Light coming in? (5, Informative)

Control Group (105494) | more than 7 years ago | (#17850602)

Pretty much, yes. The idea of Maxwell's Demon was to violate the second law of thermodynamics - once you include an external power source, its entropy increase has to be included in the system, and now you've just got a heat pump. Doing it on the nanoscale is Really Neat(tm), but it's not Maxwell's Demon.

But then, TFA doesn't have Leigh saying that it is Maxwell's Demon, just that he credits Maxwell with furthering science.

Re:Light coming in? (1)

maxwell demon (590494) | more than 7 years ago | (#17850794)

Well, I think it's obvious that I qualify (see user name) :-)

There's a nice quote from the article:
"As Maxwell had predicted long ago, it does not need energy because it is powered by light."
If light is not energy (or more exactly, does not carry energy), then I conclude that solar cells are violating the first law (because solar cells are powered by light and output energy).

However, for being an entropy-decreasing Maxwell's Demon it would suffice that there's no energy transfer from the light to the gas (or at least not enough to create that additional entropy through heating up), and in addition that there's no entropy transfer from the gas to the light (because if the light is simply carrying away entropy, it's no problem for the entropy of the gas to decrease; that's just a normal cooling process). It's especially the second part I strongly doubt: It would require the light not to be scattered from the molecules (and of course it also may not be absorbed, because that would violate the first condition). And I'm very doubtful about that.

Re:Light coming in? (3, Insightful)

kfg (145172) | more than 7 years ago | (#17851218)

That's right. Maxwell's demon is a demon. A supernatural being not subject to the laws of physics. He can arbitrarily effect the system without being affected by it. Thus there is no widening of the sytem by his introduction and no feedback effects from his actions. That's the whole point of him.

Maxwell's demon could sort a mixed bag of apples and oranges into two bags of apples only and oranges only while preserving an apples and oranges system.

If you sort a bag of apples and oranges the system is one of apples and oranges and you. I presume you are not a demon; despite what I may have heard.

KFG

Ah, I love mass media science reporting (4, Funny)

hairykrishna (740240) | more than 7 years ago | (#17850320)

"Journalist misses whole point of Maxwells demon, news at 11"

Medicinal Uses (0)

Ace905 (163071) | more than 7 years ago | (#17850322)

This looks to me like a promising step towards machinery for cleaning arteries. I imagine it won't be past our own life-times (we that aren't close to dead) before technology like this silently and efficiently ensures we never die of clogged arteries, strokes, blood clots.

Then we can sit in front of our computers all day long eating cheesy nacho's and injecting ourselves with nano fat collectors.

Mmmmm... nachos [douginadress.com] .

Re:Medicinal Uses (0)

Anonymous Coward | more than 7 years ago | (#17850786)

Interestingly, we already have micros-sized versions of these: they're called foam cells [wikipedia.org] . Problem is, then they get stuck and give you coronary artery disease. So the problem might be cleaning the arterial wall and safely transporting the junk through the bloodstream and out of our bodies as waste...

Re:Medicinal Uses (1)

Ace905 (163071) | more than 7 years ago | (#17850940)

What we need is a foam-cell with a small chunk of unreacted potassium enveloped in a bucky-ball attached to it, with a detonator mechanism.

"Oohhh, jeeez my chest feels like it's on fire"
"You're probably just getting over a heart-attack... drink some milkshake, it'll cool ya down"

---
speaking of milkshake [douginadress.com]

Re:Medicinal Uses (1)

dbIII (701233) | more than 7 years ago | (#17852106)

This looks to me like a promising step towards machinery for cleaning arteries.

No - that's a bicycle :)

It's actually pleasantly surprising to see a press article titled nanotechnology which is actually on the topic. Drexler et al were not talking about sub-micron particles in toothpaste when they used the term.

Now this... (3, Funny)

IAstudent (919232) | more than 7 years ago | (#17850358)

is what I call a Maxwell's Demon [wikipedia.org]

I thought.. (5, Interesting)

Talonator (594765) | more than 7 years ago | (#17850368)

.. that the point of the Maxwell's Daemon was to illustrate a hypothetical 'perpetual motion' machine which would generate gradients with no energy input.

In the classical example, the Daemon sits at a gate between two chambers, where both are filled with particles of random velocities. When a slow particle approaches from the left or a fast one from the right, the Daemon keeps the gate shut. When a fast one approaches from the left or a slow from the right, however, the Daemon opens the gate and lets the particle pass, thus passively generating a gradient of slow/fast particles.

As to its 'energy from nothing' nature, it's been shown that the actual switching could occur with zero energy use, but (I believe) the act of resetting the Daemon's velocity measurement device would require some energy.

Long story short, the reason that the idea of a Maxwell's Daemon is important is not because it's a nanomechanical switch, but because it was thought to be an anti-entropic system with no energy use. The actual action that the Daemon was performing is quite irrelevant, and so I take offense at the title of this story. That's all.

Re:I thought.. (3, Funny)

QuickFox (311231) | more than 7 years ago | (#17850890)

The actual action that the Daemon was performing is quite irrelevant, and so I take offense at the title of this story.
Mod parent funny. He expects accuracy on Slashdot.

Re:I thought.. (1)

amRadioHed (463061) | more than 7 years ago | (#17851938)

I fairly scientifically literate and yet I've never understood the point of Maxwell's Demon. The first time I heard of it I thought, "That's stupid, why is he ignoring the work the Demon is doing?". I still think that. Am I missing something? Does this thought experiment really teach us something about physics? If so I don't see it.

WTF? (4, Insightful)

arkham6 (24514) | more than 7 years ago | (#17850376)

Is this article written for scientific morons?

"it does not need energy because it is powered by light."

As I understand it, the object the demon works on has to be isolated from the universe. If this 'demon' is powered by light, its not isolated, because outside influences are acting on it.

I think maxwell's thought experiment still stands, thanks come again.

Re:WTF? (1)

OldChemist (978484) | more than 7 years ago | (#17851654)

I share your amazement. I thought E = hv or E = mc2 So powered by light means no energy required? Gaggg...

Re:WTF? (1)

RMB2 (936187) | more than 7 years ago | (#17852032)

I am also completely baffled by that statement in TFA; to my knowledge, light IS a form of energy. This statement clearly suggests that the author thinks it is not.

Beyond my disgust with Patricia Reaney's (author) obvious lack of scientific understanding, the point of Maxwell's Demon is that he can SELECTIVLY allow passage of molecules of different energies, not to "capture molecules" as the article describes. While interesting, that is NOT the point at all; by using knowledge of the state of the particles, the Demon is able to alter the distribution of particle momenta in two different chambers, thus changing the energies, specifically kinetic energy (i.e. temperature).

The reason the original thought experiment remains exactly that, and unrelated to the discovery in TFA, is that it implies either intelligence AND molecule-altering capabilities, or some violation of thermodynamic laws would be required. I don't mean to disparage the discovery, it may well be valuable to nanotechnology in its own right, but it is NOT, in my estimation, a creation of Maxwell's Demon.

Additionally, I remember playing some simple "game" with a bunch of balls flying around, in a box, and all you could do was click to make the wall separating the box in half disappear. There were counters to indicate the "energy" on either side. Anybody know what I'm talking about (it's not Maxwell's Maniac, it was simpler than that)

Re:WTF? (1)

Torvaun (1040898) | more than 7 years ago | (#17852256)

Jezzball. Using walls to separate the area which had balls from that which did not.

Re:WTF? (1)

RMB2 (936187) | more than 7 years ago | (#17852290)

Nope, it's certainly not Jezzball, although somewhat similar. What I'm thinking of isn't so much a game as a "simulation"; there are maybe 500 balls, and the a single middle barrier (which you can open/close) and the average energies of both sides are displayed on the top.

Nanotechnology (5, Interesting)

Lazerf4rt (969888) | more than 7 years ago | (#17850384)

Leigh believes nanoscale science and engineering could have a huge impact on society - comparable to the impact of electricity, the steam engine and the Internet.

But quite how, is difficult to predict.

So far, the biggest impact of nanotechnology on society is that society is full of geeks who swoon at the idea of nanotechnology being the future. Why are so many nerds just dying for the nanotechnology future to get here? What's wrong with the present?

Things that seem like a Harry Potter film now are going to be a reality.

I thought the inspiration for nanotechnology came from Sci-Fi books and Star Trek. Now Harry Potter is the big inspiration?

Re:Nanotechnology (1)

Rycross (836649) | more than 7 years ago | (#17850520)

I thought the inspiration for nanotechnology came from Sci-Fi books and Star Trek. Now Harry Potter is the big inspiration?


There was some quote in reference to writing sci-fi by some author. Can't remember the source.

"Any sufficiently advanced technology is indistinguishable from magic."

Re:Nanotechnology (1)

dreddnott (555950) | more than 7 years ago | (#17850756)

I believe that quote is properly attributed to Arthur C. Clarke.

Re:Nanotechnology (1)

wiggles (30088) | more than 7 years ago | (#17850656)

Why are so many nerds just dying for the nanotechnology future to get here?
Get your answer here [amazon.com] .

Re:Nanotechnology (1)

Lazerf4rt (969888) | more than 7 years ago | (#17850708)

You mean from a Sci-Fi book?

Re:Nanotechnology (1)

cowscows (103644) | more than 7 years ago | (#17851098)


Why are people talking about alternative fuels? Why do people worry about a sustainable future? What's wrong with sticking with oil?

Why are so many people fascinated by space travel? Fuck going into space. What's wrong with Earth?

Why are so many techies talking about new hardware? What's wrong with the computer you have? What more you could possibly want?

You're right. Today is perfect. I hope nobody ever events anything new ever again. That wouldn't be cool at all.

What's the matter with you?

Re:Nanotechnology (1)

Lazerf4rt (969888) | more than 7 years ago | (#17851410)

You're right. Today is perfect. I hope nobody ever events anything new ever again.

Strawman alert! I never said today is perfect. I merely asked a question. The implied meaning took place entirely in your mind. You just got trolled!

Re:Nanotechnology (1)

cowscows (103644) | more than 7 years ago | (#17851566)

You're right! Your question could not have possibly implied anything at all! You said something stupid, but since it's mildly ambiguous, no one can justifiably comment on it!

In fact, here's a comic someone made that touches on this point:

http://www.xkcd.com/c169.html [xkcd.com]

Re:Nanotechnology (1)

Lazerf4rt (969888) | more than 7 years ago | (#17851766)

You're right! Your question could not have possibly implied anything at all! You said something stupid, but since it's mildly ambiguous, no one can justifiably comment on it!

That straw man sure says a lot of things on my behalf.

Re:Nanotechnology (3, Insightful)

Jerf (17166) | more than 7 years ago | (#17851236)

What's wrong with the present?
The present is freaking awesome . There are entire new categories of awesomeness that didn't even exist a hundred years ago, and it's getting better all the time. If I even started listing them, I'd sound utopian, even though it's not an unrealized future I'm describing, but the actual present. There is no-when I'd rather live, if I can only select from the past, and assuming I don't get to chose who I'd end up as (an assumption that people frequently sneak in; are you sure you want to live in 1500 if you are almost certain to end up a dirt-poor peasant somewhere or other?).

But since the present actually exists, we can see its problems. As freaking awesome as it is, it is still far from perfect.

But the future doesn't actually exist as anything but our dreams. So, natually, it has no problems. So the future is even awesomer, and the present sucks to the extent that it doesn't live up to my awesome future dreams.

People who have actually taken a look at the future in a clear-eyed way say it'll still have problems, and it's still anybody's guess as to whether they'll be bigger or smaller than the problems of today. Still, since staying in the present doesn't really seem to be an option, it seems we'll find out. One thing's for sure, we won't be jumping straight to a mystical paradise anytime soon.

In the meantime... enjoy what is here and what you have. If you're certain the present sucks, it will... for you. Why add the misery of thinking everything sucks more than it actually does to the still-real misery that life often offers you?

Re:Nanotechnology (0)

Anonymous Coward | more than 7 years ago | (#17851270)

Go and read the Dance of the Gods tetralogy.
hint: first three tomes ale almost pure fantasy. ...and there's the fourth one.

http://www.gaslightbooks.com.au/4part/authorb2.htm l#Brenner/ [gaslightbooks.com.au]
http://www.amazon.com/exec/obidos/search-handle-ur l/104-9121897-9397556?_encoding=UTF8&search-type=s s&index=books&field-author=Mayer%20Alan%20Brenner/ [amazon.com]

Re:Nanotechnology (1)

Lazerf4rt (969888) | more than 7 years ago | (#17851556)

Four books? Yikes. Couldn't you just sum them up for me? I see they're fantasy and not Sci-Fi... Do they fall into the Harry Potter-side of the inspiration?

Re:Nanotechnology (1)

feepness (543479) | more than 7 years ago | (#17851480)

What's wrong with the present?

Because in the future we will have much better tools for creating a better future.

Re:Nanotechnology (1)

Alsee (515537) | more than 7 years ago | (#17852792)

Why are so many nerds just dying for the nanotechnology future to get here? What's wrong with the present?

Because full blown nanotechnology means you can pretty much BitTorrent real objects. You just download the datafile for an object, and everything from food to cars to computers to houses could be created at will for everyone virtually for free - grown out of raw dirt and solar energy. You could even BitTorrent a RealDoll [realdoll.com] for example.... not that that is particularly relevant to why so many nerds just dying for the nanotechnology future to get here and what's wrong with the present.

-

Re:Nanotechnology (1)

treeves (963993) | more than 7 years ago | (#17852892)

I thought the inspiration for nanotechnology came from Sci-Fi books and Star Trek. Now Harry Potter is the big inspiration?

Neither. If you have to have a single source inspiration, it would have to be Richard Feynman, 1959.

http://www.zyvex.com/nanotech/feynman.html [zyvex.com] was the first search hit on Google.

Edinburgh - Not Edimburgh (1)

nucleartool (1047692) | more than 7 years ago | (#17850392)

Sorry, proud Scottish fella... They may take our lives but they will never take out freedom!

Our - Not Out (1)

Kim Jong Ill (1033418) | more than 7 years ago | (#17851030)

Sorry, worthless spelling Nazi... :)

Re:Edinburgh - Not Edimburgh (1)

teslar (706653) | more than 7 years ago | (#17851164)

You obviously missed the news that to celebrate and deepen the French-British relationship, names of cities on either side of the channel are changed to contain one half of the French and one half of the English name - hence Edimbourg + Edinburgh = Edimburgh

Of course you will not notice this in the name of every city. Londres + London for instance still gives London :)

:)

Off Topic - But WTF is Opinion Center Intel (4, Informative)

Ranger (1783) | more than 7 years ago | (#17850408)

Today, I see this Opinion Center with Intel under it. I check my Preferences to see if I can select other Opinion Centers or turn it off. I can't. So I go and take a look. It's a paid advertiser section. That's fine, but please label it for what it is, a Paid Sponsor Section. It's not an opinion center.

Mabye there's a place to make a comment or complaint about this, but it wasn't obvious so I posted it here.

Re:Off Topic - But WTF is Opinion Center Intel (1)

cowscows (103644) | more than 7 years ago | (#17851016)

I'm going to go out on a limb and guess that the likely response you'll get from the editors will be very similar to the text of your sig.

Cowboy Neal's Demon (3, Funny)

PIPBoy3000 (619296) | more than 7 years ago | (#17851714)

I think we're seeing Cowboy Neal's Demon, a software utility that moves links about on a page to create infinite money for the developer.

Of course, such a thing can never happen in real life, so it's all theoretical.

Re:Off Topic - But WTF is Opinion Center Intel (1)

cain (14472) | more than 7 years ago | (#17852108)

And in the upper right corner do a mouse-over of the intel link in "Opinion Center: Intel". You are treated to a moronic marketing article brought to you by the "OSTG Marketing Dept". Annoying. And no way to get rid of it. Marketing is evil.

Re:Off Topic - But WTF is Opinion Center Intel (1)

Ranger (1783) | more than 7 years ago | (#17852610)

Sadly, I noticed that too. I am reminded of a quote which I will paraphrase:

Wikipedia defines the OSTG Marketing Dept. as "a bunch of mindless jerks who'll be the first against the wall when the revolution comes,"

Re:Off Topic - But WTF is Opinion Center Intel (0)

Anonymous Coward | more than 7 years ago | (#17852678)

You can hide it by clicking the little down-arrow just to its left. Just like, well, almost any other control ever that has down-arrows like that.

Re:Off Topic - But WTF is Opinion Center Intel (1)

cain (14472) | more than 7 years ago | (#17852810)

No - your other right. Look under "Why Subscribe" under the search bar on the right.

Re:Off Topic - But WTF is Opinion Center Intel (1)

PoderOmega (677170) | more than 7 years ago | (#17852222)

And I see the Vendor's section with AMD in it is gone as well. I guess Intel put up enough cash to beat out AMD and get a misleading section name.

Re:Off Topic - But WTF is Opinion Center Intel (1)

illuminatedwax (537131) | more than 7 years ago | (#17853262)

Hey! Take your opinions over to the Free Speech Zone, buddy! We don't want 'em here!!

Not actually a Maxwell Demon... (5, Informative)

kebes (861706) | more than 7 years ago | (#17850452)

Let's get the pedantic "This is not actually a Maxwell Demon" comments out of the way first. The original thought experiment of Maxwell's Demon [wikipedia.org] was to suggest a hypothetical creature/device/demon that could watch molecules and make decisions based on what those molecules were doing. By watching the motion of molecules, the demon could open/close a flap and thus sort molecules by kinetic energy. This would allow the demon to generate a hot gas out of nowhere, without any energy input. This would thus contradict thermodynamics (which states that entropy always increases, etc.).

The reason that such a demon cannot be created is that the very act of making an observation (of a gas molecule's trajectory, for instance), requires the usage of energy. And on the scale we're talking about, that usage of energy is exactly the 'work' you are doing to raise the temperature of the gas in sorting the molecules. Thus no such thing as a maxwell demon can be made, and thermodynamics is intact.

This most recent report, as stated, requires an input of energy to move/sort molecules. Thus it doesn't violate thermodynamics and it's not really a Maxwell Demon. The article seems a bit confused on this issue, stating:

As Maxwell had predicted long ago, it does not need energy because it is powered by light.
I would content that the light is an input of energy, and thus saying "it does not need energy" is rather silly.

In any case, the actual research (see David Leigh's page [ed.ac.uk] ) is about photo-activated molecular shuttles: molecules that switch between well-defined states with input of light. You can thus trap or move other molecules using light. Certainly one step towards the much-anticipated "nanotechnology" but not quite the fine control of molecular positions one would imagine when using the term "Maxwell Demon."

Re:Not actually a Maxwell Demon... (0)

Anonymous Coward | more than 7 years ago | (#17850730)

> The reason that such a demon cannot be created is... on the scale we're talking about, that usage of energy is exactly the 'work' you are doing to raise the temperature of the gas in sorting the molecules.

The reason you've provided seems like a technological limitation, not a fundamental law of physics. Couldn't you theoretically have extremely heavy gas molecules and a nano-device that performs observations using low-energy photons that barely disturb the gas molecules? Couldn't a Maxwell's demon working on macroscopic-sized superballs be demonstrated?

BTW my understanding is that the idea of Maxwell's demon is not to create energy out of nothing, but rather a way to cheaply extract the thermal energy out of a hot gas and end up with a cold gas and a more useful form of energy, like electricity.

Re:Not actually a Maxwell Demon... (1)

kebes (861706) | more than 7 years ago | (#17851036)

my understanding is that the idea of Maxwell's demon is not to create energy out of nothing, but rather a way to cheaply extract the thermal energy out of a hot gas and end up with a cold gas and a more useful form of energy
You're right, and thermodynamics tells us these things are related. If you can find a way to reverse the flow of entropy, that's a way of creating "useful energy" out of "useless energy". Thus you could create electricity using just the ambient temperature around you. But, since thermodynamics says that entropy always increases, this is in practice not possible.

The reason you've provided seems like a technological limitation, not a fundamental law of physics.
I agree it sounds like only a technical problem, but if you do the calculation you will find that it is actually a very fundamental limit. There are established limits in information theory, for instance, that describe the minimum amount of entropy you'll need to creat in order to encode information. Basically if you look at it, the demon would have to do something in order to: (1) determine the velocity of a molecule, (2) decide what to do, and (3) open/close the flap. These actions will increase the entropy of the demon far more than he's decreasing the entropy of the gas (by sorting the gas molecules).

Remember it's not just a matter of disturbing the gas molecules, it's a matter of the demon itself needing to increase in entropy in order to make the measurement. Although your hypothetical 'macroscopic-sized superballs' may be easier to sort, the amount of entropy decrease you'd get by sorting them would be very very small, and would be offset by the increase in entropy in the observer.

Re:Not actually a Maxwell Demon... (1)

Michael Woodhams (112247) | more than 7 years ago | (#17851534)

These actions will increase the entropy of the demon far more than he's decreasing the entropy of the gas (by sorting the gas molecules).
This is related to the Von Neumann-Landauer limit [wikipedia.org] which specifies how much heat you have to dissipate to reset your Maxwell's Demon to a pristine state after it has made a decision. This in turn is related to Reversable Computing, which seeks to improve the energy efficiency of computers by avoiding such resets wherever practical.

Re:Not actually a Maxwell Demon... (1)

gardyloo (512791) | more than 7 years ago | (#17851100)

Couldn't a Maxwell's demon working on macroscopic-sized superballs be demonstrated?

      Yes, and according to some, it will be achieved when scientists dump a bunch of concrete spheres into a mud volcano in the nearish future.

Re:Not actually a Maxwell Demon... (0, Flamebait)

NeuralSpike (968001) | more than 7 years ago | (#17851928)

Ummm... cite your source please (if only so some of us can figure out what you're talking about).

Re:Not actually a Maxwell Demon... (1)

Lord Ender (156273) | more than 7 years ago | (#17851052)

Did you honestly just suggest that measuring the velocity of an object (by shining a light on it) consumes as much energy as is in a the kinetic energy of a moving massive object? That doesn't pass the laugh test.

Re:Not actually a Maxwell Demon... (3, Interesting)

kebes (861706) | more than 7 years ago | (#17851226)

Well you have to a little careful here. The argument relates not to energy per se, but the energy dispersal, i.e.: entropy. That's why I said 'usage of energy' instead of simply 'energy.' It turns out that entropy increase in the demon is larger than the entropy decrease you get by sorting gas molecules.

The argument would be the same with massive objects. If you attempt to devise a way to generate a low-entropy situation using "massive moving objects" then I assure you that there will be a corresponding increase in entropy elsewhere that will offset it. (Remember that a fast-moving object has high kinetic energy, but this doesn't say much about the entropy of the system it is a part of.)

Re:Not actually a Maxwell Demon... (1)

not-admin (943926) | more than 7 years ago | (#17851442)

No, he suggested that the process of measuring the velocity AND THEN storing, analyzing, and acting upon that observation will create as much (or more) entropy as the device will eliminate in the particles.

It's not Edimburgh (1)

gkAndy (81647) | more than 7 years ago | (#17850490)

It's Edinburgh.

Re:It's not Edimburgh (0)

Anonymous Coward | more than 7 years ago | (#17852820)

Could you come to the point? I have to go feed my cat.

But can it play the guitar? (1)

Rude Turnip (49495) | more than 7 years ago | (#17850512)

Am I the only one who the only one who thought TFA was about a bisexual space alien rock star?

A little late for the demo.. (0)

Anonymous Coward | more than 7 years ago | (#17850568)

First demonstration of Maxwell's demon was in 1928. The principal has been in commercial use since then.

For more info: (sorry guys don't know how to make it link.)
http://www.exair.com/vortextube/vt_page.htm?source =google&group=vortextube [exair.com]

Re:A little late for the demo.. (1)

Radon360 (951529) | more than 7 years ago | (#17851072)

A little more of a direct link to the info on the vortex tube [exair.com] .

Re:A little late for the demo.. (0)

Anonymous Coward | more than 7 years ago | (#17852376)

Except its not a Maxwell's demon, because you're increasing entropy when you compress the air.

His other not-so-famous work (4, Funny)

0xABADC0DA (867955) | more than 7 years ago | (#17850596)

Pity the researchers weren't able to create Maxwell's lesser-known "Angel", a device that -- using no power at all -- sits on a barrier and sorts molecules based on their goodness. All matter composed of "charm", "up" and "top" quarks collect on one side, whereas matter composed of the hateful 'strange', 'down', and 'bottom' quarks collect on the other.

This would totally change the world in the short term by finally providing a means to mass-produce holy water, and eventually even purifying the entire world of 'evil' particles (ie collect all the hateful particles together, send them up on the 'space elevator to heaven' and launch into the void).

Re:His other not-so-famous work (4, Funny)

isaac (2852) | more than 7 years ago | (#17851058)

Flavorist! That strange quark never got to chose to be strange - it was just made that way. It's not fair to discriminate on that basis.

-Isaac

Re:His other not-so-famous work (1)

Chris Burke (6130) | more than 7 years ago | (#17851930)

This would totally change the world in the short term by finally providing a means to mass-produce holy water, and eventually even purifying the entire world of 'evil' particles (ie collect all the hateful particles together, send them up on the 'space elevator to heaven' and launch into the void).

Leading to the eventual clash between us and whatever planet our huge ball of quantum-mechanically perfect evil lands on.

Which would be sweet. This is the best plan ever.

Re:His other not-so-famous work (0)

Anonymous Coward | more than 7 years ago | (#17852286)

Leading to the eventual clash between us and whatever planet our HUGE ball of quantum-mechanically perfect evil lands on.

Sounds like you have more of a 'the world is half evil' kind of personality. Myself, I believe 'the world is half good'. Bush? He's more of a 'half world good' [thinkprogress.org] kind of guy.

Consider (4, Interesting)

HomelessInLaJolla (1026842) | more than 7 years ago | (#17850632)

Most of the Maxwell's Demon experiments deal with particles which are assumed to be infinitely small and particles which are one iota larger than infinitely small.

Consider Maxwell's Demon operating on entire galaxies at a time. An infinitely large mass (typified as a black hole) has a much larger gravitational field than a mass which is one iota less than infinitely large. If Maxwell's Demon were a gravitational capacitor (ie. its effect is only realized when the gravitional field resulting from a mass exceeds a certain level but exhibits no behavior up to one iota less than that gravitational field) then the Demon could, possibly, move out of the way and selectively allow the object of infinite mass (eg. a black hole) to pass while reflecting all objects of lesser mass.

I first proposed a similar theory years ago when working for Abbott Laboratories.

That's interesting (1)

AlphaLop (930759) | more than 7 years ago | (#17850640)

but I wonder if this tech could be used to make a much more efficient solar cell?

Re:That's interesting (0)

Anonymous Coward | more than 7 years ago | (#17851056)

To power a fridge?

Start command (2, Funny)

Anonymous Coward | more than 7 years ago | (#17850674)

Forget thermodynamics, is the command to start the demon /etc/init.d/maxwell start?

Re:Start command (1)

maxwell demon (590494) | more than 7 years ago | (#17851522)

/bin/maxwelld: Entropy fault.
Process Therminated.

Lack of diagrams (5, Funny)

LiquidCoooled (634315) | more than 7 years ago | (#17850742)

I notice there wasn't a schematic or diagram of the engine, but I scoured the web and managed to find one.

Here it is:

      .

Re:Lack of diagrams (0, Redundant)

oftencloudy (1047554) | more than 7 years ago | (#17851014)

whoa whoa! that diagram is far too large to pertain to the subject at hand. please redraw or use mine:


Re:Lack of diagrams (1)

poopdeville (841677) | more than 7 years ago | (#17851446)

Wow! Slashdot lets us post pics now! Here's a miniature goatse:

  =EO3=

Good news for nanosports fans! (1)

AndroidCat (229562) | more than 7 years ago | (#17850882)

A new player for the Edinburgh Engines in the Bucky Basketball League!

Edinburgh not Edimburgh! (0)

Anonymous Coward | more than 7 years ago | (#17850968)

Sigh...

Nano is the new media prefix buzzword... (0)

Anonymous Coward | more than 7 years ago | (#17850988)

Count how many times it's used in the article...

There are other engineering magnitude prefixes out there (micro, pico, etc,)...some may be more appropriate in certain cases. How about using the appropriate ones before someone files suit on the basis of discrimination?

a sudden epiphany (0)

scooviduvoctagon (801935) | more than 7 years ago | (#17851020)

I wonder if they've considered a beowulf cluster of those things?

I for one... (0)

Anonymous Coward | more than 7 years ago | (#17851170)

welcome our new light-powered molecule-sorting overlords.

How it works (2, Informative)

baby_robots (990618) | more than 7 years ago | (#17851220)

I am currently working towards a PhD in this subject. I think that the first thing to realize is that he has not yet made a motor. He has molecular ratchet as proof of concept towards a molecular motor.
          In layman's terms this is how the ratchet works. First, the molecule is essentially a dumbbell with a ring around it. The ring can move freely back and forth across the dumbbell, but prefers to be at either end. The dumbbell can be bent only near one end, which prevents the ring from moving. The ring catalyzes the transition from bent to strait, to allow motion. The thing is, is that the ring needs to be next to the bend for a significant amount of time to unbend the dumbbell.
            So, when the ring is next to the bend, it can straiten it temporally to move across. When it is far away, it can no longer move across the bend, and since the second binding site is far away from the bend, it is stuck there. If you have two dumbbells looped end-to-end with one ring, then you would have a molecular motor. The ring is acting as "Maxwell's Daemon" to allow movement across the system.

Here's a link to the actual journal article if you care to read: http://www.nature.com/nature/journal/v445/n7127/pd f/nature05452.pdf [nature.com]

What? No one else thought of Velvet Goldmine? (1)

vistic (556838) | more than 7 years ago | (#17851300)

Got tired of wasting gas living above the planet
Mister, show me the way to earth
The boys of Quadrant 44 with their vicious metal hounds
Never come around here no more
Sometimes I wonder if I'm still alive
Six feet down at age 25
Maxwell Leather Demon rock hand jive

I came down like water
For the age of solar
Hail to the father
Kiss your sons and daughters
Goodbye goodbye
Steam steady roller
Lady tongue controller
Ten feet tall, better walk it back down

Despite the great duress, always get off 'cause damn it!
It's the only sure-fire way to win
Your poison doesn't hurt me, no
Tender wine disguised in a milk-fat fair kiddie show
I'm here to celebrate the one below
At last I've heard from good God above
As the slap on my ass by a lipstick-kissed elbow glove

I came down like water
For the age of solar
Hail to the father
Kiss your sons and daughters
Goodbye goodbye
Steam steady roller
Lady tongue controller
Ten feet tall, better walk it back down
I came down like water
For the age of solar
I came down like water
Kiss your sons and daughters

Ten feet tall, better walk it back down

Maxwell's Demon? (1)

Oktober Sunset (838224) | more than 7 years ago | (#17851326)

I'm certain that captain baseball bat boy will kick his ass.

Re:Maxwell's Demon? (1)

krusher_00 (1058744) | more than 7 years ago | (#17852226)

From Wikipedia:
Maxwell's Demon is an enemy of Captain Baseball bat-boy in the animated series featured in the game Max Payne, at first seeming to be a coincidence in names until a character is quizzed on his knowledge of the game to save his life. The question being "Who was the original creator of Maxwell's Demon?" The character cited both the Captain Baseball bat-boy character who created the demon, as well as the show's writer, but was killed for not answering "James Clerk Maxwell".

And here I came, expecting to see a TV series. :-(

What I'm wondering (off topic) (0, Offtopic)

Robber Baron (112304) | more than 7 years ago | (#17852012)

What I'm wondering, is how many of those girls in that dating site that was featured in one of the ads that this story linked to are going to wind up getting asked for dates now, due to the inundation of desperate, geeky basement-dwellers?

Obligatory Simpson's quote (4, Funny)

avitzur (105884) | more than 7 years ago | (#17852098)

"Lisa! In this house we obey the law of thermodymanics" - Homer Simpson.

Demon? who cares.... (0)

Anonymous Coward | more than 7 years ago | (#17852232)

I'm waiting for his silver hammer.

Not the First Time (1)

MarkLewis (593646) | more than 7 years ago | (#17853088)

An implementation of Maxwell's Demon already exists, called the Hilsch Vortex Tube: http://en.wikipedia.org/wiki/Vortex_tube [wikipedia.org]

It takes gases (such as air) and separates them into hot streams and cold streams, and is already in commercial use. It requires pressure to operate, and dissipates enough energy in the process that it's certainly not free energy. It's less energy efficient than a conventional air conditioner.

Ob. Matrix... (1)

cojsl (694820) | more than 7 years ago | (#17853160)

"The device is powered by light..." QUICK, burn the sky!
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