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Maxwell's Demon Soon A Reality?
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."
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.
Reality has a conservative bias: it conserves mass, energy, momentum...
.. 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.
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?
I thought the inspiration for nanotechnology came from Sci-Fi books and Star Trek. Now Harry Potter is the big inspiration?
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.
the NPG electrode was replaced with carbon blac
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.)
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!)
imho the laws of thermodynamics are perfectly functional but the third one - no addition or subtraction (oh wait is that the first, conservation? damn i don't even know, maybe i should read wikipedia so i can say something useful) - what about division. i know, in transistor logic subtraction is implemented as multiple subtractions (or have i got that wrong, i know multiplication is implemented that way) but in mathematical terms making more by cutting everything into smaller pieces means you respect conservation of energy. in that idea i am suggesting that relativity is a loophole in thermodynamics. i don't understand why this has not been noticed before, maybe it has but i have yet to hear of anyone else suggesting this. there's some other aspects like finite but unbounded space and the puzzing mechanism that might be behind any such division process (second harmonics, but also more harmonics, if one assumes a wave mechanics model).
in any case this sounds like a fancy form of polarisation being it filters particles by velocity (in the physics sense of direction and speed) and if it works on photons why not atoms too?