Maxwell's demon
Posted: Mon Mar 12, 2012 6:15 pm
I've posted a couple of times ideas about how one might violate the oversimplified take on the 2nd law of thermodynamics - all you need is a selection process, or some nonlinearity someplace to pull it off.
For example, it's been observed that a tungsten substrate with a bunch of protruding rods starts emitting visible light before it's even "red hot". In this case, the little rods are tuned dipoles, and are emitting energy at their resonance from phonons at the "tail" of the maxwell distribution, and those "tails" are replaced by random interactions as they are lost.
The one I thought of was based on Brownian motion. Suspend a tiny magnet in something hot, then wind coils around it all three axes - with perfect diodes, you could then sum the energy from the coils, and from multiple cells (you'd need quite a few to make any real amount of energy) to get electricity - while the "battery" cools itself. Taken to an extreme, of course, it would stay warm as any temperature differential on this planet tends to create things like convection.
Now, in one day, there are two more at least plausible articles on IOP about maxwell's demons that might actually be real. I was only 40 years ahead of them.
http://physicsworld.com/cws/article/news/48889 In this one, the fact that electrons have higher speed for lower energy in graphene than anything else is the "nonlinearity".
http://physicsworld.com/cws/article/news/48882 In this one, a led uses phonons (lattice vibrations, or heat) to boost the probability of emitting a higher energy photon. IN this case, the band gap is the "selector".
Could the world be saved already? Are there flaws in the observations here? I think the premises are plausible, but when I ran the numbers for my own thought, it turns out you need a heck of a lot of it to get even a microwatt - now, small energies like that can be useful - especially if they last forever, but of course the world is looking for mega, not pico watts.
For example, it's been observed that a tungsten substrate with a bunch of protruding rods starts emitting visible light before it's even "red hot". In this case, the little rods are tuned dipoles, and are emitting energy at their resonance from phonons at the "tail" of the maxwell distribution, and those "tails" are replaced by random interactions as they are lost.
The one I thought of was based on Brownian motion. Suspend a tiny magnet in something hot, then wind coils around it all three axes - with perfect diodes, you could then sum the energy from the coils, and from multiple cells (you'd need quite a few to make any real amount of energy) to get electricity - while the "battery" cools itself. Taken to an extreme, of course, it would stay warm as any temperature differential on this planet tends to create things like convection.
Now, in one day, there are two more at least plausible articles on IOP about maxwell's demons that might actually be real. I was only 40 years ahead of them.
http://physicsworld.com/cws/article/news/48889 In this one, the fact that electrons have higher speed for lower energy in graphene than anything else is the "nonlinearity".
http://physicsworld.com/cws/article/news/48882 In this one, a led uses phonons (lattice vibrations, or heat) to boost the probability of emitting a higher energy photon. IN this case, the band gap is the "selector".
Could the world be saved already? Are there flaws in the observations here? I think the premises are plausible, but when I ran the numbers for my own thought, it turns out you need a heck of a lot of it to get even a microwatt - now, small energies like that can be useful - especially if they last forever, but of course the world is looking for mega, not pico watts.