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Does Nantenna (nano antenna) violates 2nd Law of Thermodynamics ?

Nantennas absorb infrared heat and convert it in direct current. Quote from Wikipedia:

He did not discuss whether or not this would violate the second law of thermodynamics.

Some people said that that Nantennas and Solar Cells are not thermodynamics. I do not understand that thesis.

That is why I have re-phrased question:

Are Nantennas a perpetual motion machine of Second Kind ?

As I know: 2nd law XOR perpetual motion of second kind

PS: I can't agree that answers are prooving that that second law is not violated by nantennas and MIM diods. If someone has to say anything about the subject then I would be happy to read that. Thank You all for responses!

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Please, comment if you minus. I quote wikipedia, It is mentions that my question make sense. If someone says it does not violates then I have to argue that it does when it make sense. –  Max Sep 30 '12 at 17:34
    
I am the one who put those words into the wikipedia article. What I wanted to say was: "Obviously this application would violate the second law of thermodynamics." But I ended up writing that more understated and diplomatic sentence which you quote, because of wikipedia's referencing rules. Indeed, if you have a room at temperature T, and a nantenna device at the same temperature T, it cannot charge a battery. This is a textbook example of the Second Law. –  Steve B Oct 5 '12 at 21:11
    
Inventor of nantennas Dr. Steven Novack claims applications for nantennas that violate 2nd law in his interview on radio station. But absolutely most science community believe he is wrong and such applications are impossible as they violate 2nd law? Is that correct? –  Max Oct 5 '12 at 21:44
    
I would bet a large sum of money that the overwhelming majority of professional physicists would agree with my assessment that the device cannot possibly work as advertised in the application in question, because if it worked then it would violate the Second Law. However, I have not actually done a survey! –  Steve B Oct 5 '12 at 23:08
    
Thank You! I find it strange that someone invented nantennas, got nanotechnology award for the invention and claimed wrong or revolutional application for the invention and it is shyly ignored by science community for 4 years already. –  Max Oct 5 '12 at 23:42
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3 Answers 3

up vote 7 down vote accepted
+100

First of all, nantennas in general don't violate the second law of thermodynamics, so they are not perpetual motion machines of second kind. As long as the total entropy goes up, the second law is obeyed. In other variables, it really means that a part of the incoming heat has to heat the nantenna up but there may still be a lot of energy left for energy production, much like in any other heat engine.

The Wikipedia suggestion that natennas could violate the second law only referred to a particular application hypothesized by Mr Novack. If he could be cooling the room while getting energy out of it, and if the gadget to cool the room were not connected to any cooler heat bath, then it would indeed be a perpetual motion machine of second kind and it would be impossible.

The reason why Nature makes it impossible is kind of trivial. If the room has temperature $T$, then the nantenna or "power plant" may only be kept at the same temperature $T$ if there's equilibrium. But if that's the case, the nantenna emits thermal radiation, too. So even if it absorbs some incoming radiation, it still radiates its own. They're balanced and the energy gain is zero. Solar cells and "legitimate applications" of nantennas can only create energy because they work with incoming light whose "own" temperature is higher than the temperature of the solar cell or nantenna itself. For example, solar radiation has the temperature comparable to 5,500 Celsius degrees.

The solar cells are effectively heat engines operating between this high temperature and a much lower temperature of the ground. The same is really true about life on Earth, too. The energy from the Sun may be converted and is often converted to useful energy or work because the high-energy photons from the Sun – which correspond to a high temperature and therefore a low entropy per unit energy ($E\sim TS$) – are processed on Earth and the energy is finally emitted in much lower-temperature "infrared" thermal photons – which carry a higher entropy. So the entropy can go up even if a part of the incoming energy is converted to useful work. The temperature inequality between the solar surface (and the solar radiation) on one hand and the cool temperature of the outer space is necessary for the Sun to play this often praised beneficial role.

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But they have MIM diodes connected to Nantennas. Such diods operated at up to 150 THz. Diods are rectifying currents. That is why it will not radiate back. It covers most IR spectrum in the room. When news about nantennas arrived in 2008 I read that it has cooling effect. But I can't find it now. Same rectifying effect at lower frequencies are used in wireless chargers for mobile phones. –  Max Sep 23 '12 at 17:50
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@Max It's just an electrical analogy of the Brownian ratchet. It will only work if there is a temperature difference between the radiation source and the diode. –  mmc Sep 23 '12 at 22:29
    
There are random alternating currents that diodes rectify. That is why nantenna becomes colder and energy goes away as direct rectified current. –  Max Sep 24 '12 at 15:58
    
@Max there is no perfect rectifier. Read and understand the Brownian ratchet article. –  user2963 Sep 26 '12 at 14:55
    
If rectifier efficiency would be 1% then it still will take energy out from system as direct current. MIM diodes operating at 150Thz have 40% efficiency. 150Thz is most IR spectrum. Every body radiate at IR spectrum. –  Max Sep 26 '12 at 15:28
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This is not the unique instance where heat is transformed in electricity. Thermocouple works on this principle and is perfectly described in classical thermodynamics. http://en.wikipedia.org/wiki/Thermocouple

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Does thermocouple have a cooling effect? I think it requires difference of temperatures to produce electricity. –  Max Sep 23 '12 at 18:57
    
Yes they do have a cooling effect which is even used in some aquarium tank cooling device. And you are right, they require a temperature difference to produce electricity. –  Shaktyai Sep 24 '12 at 12:08
    
Is it like Peltier element? Because Peltier has cold and hot sides. But nanoantenna with diod rectify alternating current at 150 Thz into DC and there is no temperature difference. –  Max Sep 24 '12 at 12:56
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It is just a thought : on the quantum level is that still true. I explain, it is possible that on quantum level, energy is absorbed and emitted or converted into other energy. For example : the room is cooled by a quantum-pump. This pump generates electrical power which turns a ventilator. The net entropy is lower at the end. Which is impossible. But on the quantum level this is different. Hence the choice of my pump; a quantum pump. Imagine it uses quantum-fluctuations of the energy of the vacuum created at the planck-length to say something (which may or may not be possible). This fluctuations are the same in all directions. Imagine we can control its directions.This control-mechanism woulc cost the same energy as the net result of the quantum-pump. But now : imagine that the control-mechanisme uses information as its source, not energy. So the fact that the quantum-pump is organised in a way, would control the net-energy of the pump.So,the information (the way you organise this pump) put into the pump, would result in a lower entropy and make turn the ventilator.

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What kind of information you need to make ventilator to rotate? Do you need to know location and direction of fluctuation? –  Max Jan 5 '13 at 22:40
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protected by Qmechanic Jan 5 '13 at 22:19

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