Casimir effect = free energy?

[Mayson]

I was doing homework one day for one of my engineering classes and I had a thought about the casimir effect. Couldn't I use this force to tap into the zero point energy? I Sketched out something quick and forgot about it (like I always do when I have an "insight"). Something someone posted here made me think about it again (I think it was the post about time and absolute zero). So here you go, discuss


Zero point enegy generator "schematic"

 

[silverpig]

If there was no friction in your device it'd break even... at absolute zero.

 

[Mayson]

Wouldn't be just like turning the crank on a generator, except this time the energy is coming from the energy in a vacuum instead of from my hand? Seems to me that as long as the casimir force were enough to overcome the friction in the pivot and move the plates closer together a (according to quick searching) large voltage would be generated which (should the capacitor be big enough) should charge the capacitor hopefully enough to get a repulsive force big enough to get the casimir plates back to their original position. In which case, the machine resets and should go on forever. With the casimir force supplying the same amount of force every time. It's the input in energy you need to overcome that lost to entropy. It also seems that this effect happens at room temperature (diminished, I think) since we can't reach absolute zero and it has been verified experimentally.

 

[BrownTown]

i know absolutely nothing about what you are talking about, and I can tell you there is no chance it will work. No free lunch...

 

[iamaelephant]

I think you are overestimating the Casimir effect. The attraction between the two plates is absolutely miniscule, it would take one of your casimir generators the size of a planet to produce a useable amount of energy.

And BrownTown you said yourself that you know nothing about the topic so don't bother responding. There are in fact legit theories about taking energy from the quantum vacuum that could well be considered a "free lunch." I won't go into detail (unless you want me to, but you will probably just wind up with a bunch of links) but suffice to say that there are scientists out there who believe that space is permeated with huge amounts of energy just waiting to be unlocked.

 

[Mayson]

I dunno according to this : http://math.ucr.edu/home/baez/physics/Quantum/casimir.html

pi h c
F = -------- A
480 L^4

Lets say we have a 1um gap between a plate that's ten meters wide and long

F = .13 newtons

Doesn't seem like much huh?

from here: http://acer.inforest.com/pdf/adcera/Energy%20Harvesting.pdf

V=gFL/A where g = the piezoelectric voltage constant. F = force. L = length, A = Cross sectional area

here: http://www.piezotechnologies.com/k270.htm

g= 26X10^-3
F= .13
L&A= Lets say it's pretty huge, how about 50 meters long and kinda thin .3um in diameter

V = 7.61109X10^11 volts

That seems like a pretty huge voltage to me.
I can guarantee that if I put that kinda voltage on a capacitor that can take it, we'd get a HUGE amount of charge on these plates and a huge force to seperate them.
Unfortunately, I have no idea what kinda force we'd need to move these plates on a pivot.

 

[iamaelephant]

Interesting, when you put the mathematics in there it doesn't seem like such a weak force after all. I'm no physicist (although I hope to be one day) but can anyone here confirm the figures? 10^11 volts is actually pretty extreme, seems like something may be off?

 

[BrownTown]

Where exactly does this method derive its energy from? IF you are getting energy then it must come from somewhere, so where is it in this example? Also, having a big force, or a huge voltage doesnt mean much if niether can be used to do work. For example if you put a 100lb block onto the ground then there is a 100lb force being exerted to keep the block up by the ground. However this force can do any work since it is not applied over any distance. On the same token, rubbing a balloon on your hair can produce thousands of volts of potential. But the energy transfered is only very minute.

 

[iamaelephant]

The force comes from the Quantm Vacuum. Basically there are fluctuations going on through all of space on a very tiny scale. These fluctuations include the production and destruction of "virtual particles," and are a product of the Heisenberg Uncertainty Principle. Now, when two steel plates or mirrors are placed exceedingly close together, some of this quantum vacuum is trapped. Real photons of light are reflected by the mirrors, and so are these fleeting virtual photons. This upsets the balance of the quantum vacuum and causes a negative energy field between the two mirrors/plates. Negative energy is a strange thing, as it means a negative mass aswell. This causes a small but measurable attraction between the plates.

So basically this energy does come from somewhere - it comes from the quantum fluctuations that permeate all of space, all of the time.

This is a very simplistic explanation, but if you're interested just google the Casimir Effect.

 

[Mark R]

So, the plates get forced together by the casimir effect - generating energy. OK.

But if you seperate them surely you have to act opposite to the Casimir force - thereby putting back the exact amount of energy you obtained from the attractive movement of the plates?

Same principle as 2 masses being attracted by gravity or magnetism.

So in your case, you obtain energy from attraction of the plates, but the electrical energy generated must later be used to seperate them - as the two energy transfers must be equal, you get no net release of energy after a complete cycle.

 

[silverpig]

Piezoelectric crystals will produce huge voltages, but at EXTREMELY low currents. It's something like 10^11 volts at 10^-20 amps.

Secondly, just think about your cycle.

Casimir effect to charge plates, plates use charge to repel casimir effect, repeat. The casimir effect must generate enough charge in the capacitors to overcome the casimir effect. That'll happen only if everything is 100% efficient, and you won't be able to get anything out of it. It's the same thing as having falling water turn a paddlewheel which connects to a pump to pull more water up to operate the paddlewheel.

 

[fsardis]

when i was young i had a similar idea. i was thinking, what if i could take an electric motor and power it up. then connect that electric motor to an electric generator. then connect the generator to the electric motor. i was thinking the motor would push the generator and the generator would make power for the motor. however, even if there was no friction the system would still need all of the power from the generator in order to turn the motor. if anyone stole power from the loop it would fade away. no free candy... i was 14...
its good you came up with such an idea though, congratulations for the creative thinking.

 

[Mayson]

If you wanted a huge current you could just use step down transformers, increase the efficiency with superconductors. Afterall, we get more casimir effect at low temperatures anyway. With the voltage source (the piezoelectric) in parallel to whatever circuit we're driving and the capacitor, we get to apply the same voltage across both. In our circuit we can use a transformer to get some nice current and the big voltage to charge the capacitor very quickly. It seems as if the repulsive force generated from the charged plates is MUCH stronger than the casimir force so even if you lost some energy due to some inefficiency you should be able to generate a strong enough force to seperate them and have a little energy left over. Instead of having the capacitor discharge into the ground to reset the machine you could even have that energy used to drive some other circuit too.


For example, with our 7.61109X10^11 volts generated.... lets say we have a .5 farad capacitor.

Q= VC = 7.61109X10^11 * .5 = 3.80555E11 Colombs

now, we have to split that charge between our two plates, so each one has 1.90277X10^11 Colombs of chage


The force between them is F = Q^2 / (2 * A * e) (I seem to remember this being the equation, seems like there should be a distance in there somewhere)

Where q = charge, A = area of the plates, e = pemitivity of free space


F = (1.90277X10^11)^2 / (2 * 100 * 8.85X10^-12) = 2.05X10^31 Newtons!!!!!


Now if we only were able to get a small fraction of that charge on each plate, I think we should be able to overcome the .13 Newtons from the casimir effect.

 

[Mayson]

Originally posted by: silverpig
Piezoelectric crystals will produce huge voltages, but at EXTREMELY low currents. It's something like 10^11 volts at 10^-20 amps.

Secondly, just think about your cycle.

Casimir effect to charge plates, plates use charge to repel casimir effect, repeat. The casimir effect must generate enough charge in the capacitors to overcome the casimir effect. That'll happen only if everything is 100% efficient, and you won't be able to get anything out of it. It's the same thing as having falling water turn a paddlewheel which connects to a pump to pull more water up to operate the paddlewheel.

I was thinking... in your analagy the casimir effect is the water, all we're doing is using it's energy to overcom gravity and spin the paddle back to the top. Whatever energy is left over we get to use to turn our grindstone. You see... we're still putting new energy into the system, but instead of it comming from the the new water flowing down the river it's comming from some quirk of quantum mechanics. It's like if I were to sit there and push on the casimir plate constantly to generate the current. I'm still converting food into energy and wasting it to move the plate, just like nature used the suns energy to turn water into rain which falls to high ground and flows in the river and your paddle wheel turns the kinetic energy into something we can use.

I'm still not saying this is a viable energy source, just that I haven't been convinced that it isn't yet.

 

[BrownTown]

just out of curiosity, how much knowledge do you have in this field? Clearly if this worked then you would be able to find someone who has attempted an expiriment ot create such a machine. If you have a PHD in Physics then maybe you are right, if you are jsut a college student who saw some equations and tried to string them together to make a perpetual motion machine your are unlikely to garner any support here for your theory. And based on the fact that you are asking people in an internet forum, and not PHDs about your hypothesis I would have to guess that you are the latter. As I have stated before, there is no free lunch, there are tons of examples where it seems like you can get one, but really they are just triking you. I would have to guess that based on the unusual nature of this force that you are simply unable to find the problem in your theory because of lack of knowledge. A good palce to start would be to try to derive the energy produced by this effect, and then find the energy used to reset the plates. If you show that a complete cycle will procede with a net increase in energy then you will win (and get the Nobel prize).

 

[silverpig]

Originally posted by: Mayson
If you wanted a huge current you could just use step down transformers, increase the efficiency with superconductors. Afterall, we get more casimir effect at low temperatures anyway. With the voltage source (the piezoelectric) in parallel to whatever circuit we're driving and the capacitor, we get to apply the same voltage across both. In our circuit we can use a transformer to get some nice current and the big voltage to charge the capacitor very quickly. It seems as if the repulsive force generated from the charged plates is MUCH stronger than the casimir force so even if you lost some energy due to some inefficiency you should be able to generate a strong enough force to seperate them and have a little energy left over. Instead of having the capacitor discharge into the ground to reset the machine you could even have that energy used to drive some other circuit too.


For example, with our 7.61109X10^11 volts generated.... lets say we have a .5 farad capacitor.

Q= VC = 7.61109X10^11 * .5 = 3.80555E11 Colombs

now, we have to split that charge between our two plates, so each one has 1.90277X10^11 Colombs of chage


The force between them is F = Q^2 / (2 * A * e) (I seem to remember this being the equation, seems like there should be a distance in there somewhere)

Where q = charge, A = area of the plates, e = pemitivity of free space


F = (1.90277X10^11)^2 / (2 * 100 * 8.85X10^-12) = 2.05X10^31 Newtons!!!!!


Now if we only were able to get a small fraction of that charge on each plate, I think we should be able to overcome the .13 Newtons from the casimir effect.

You can't get much current out of a piezo-electric crystal. You have to understand that. A piezo-electric crystal will produce its shock in a fraction of a second. Let's say that it's extremely slow (to get a lower bound on the power) and guess 1/100th of a second. You estimate 10^11 Coulombs of charge on your capacitors, and 10^11 volts. 10^11 C produced in 10^-2 seconds is 10^13 amps. Calculating the power, you're looking at 10^24 Watts of power out of a little crystal. That's about a millionth the power produced by the sun. Out of a crystal...

You are also assuming that you can saturate a .5 farad capacitor... you won't be able to. Also, try finding a capacitor with a dielectric that can handle 10^11 volts... I think you can get ones that'll do a few kV but not much more than that.

Look up how much current a piezo-electric crystal will produce and re-do your calculations. Make sure that you find out how many electrons you can get out of one and then put that number in for the charge on your capacitor.

 

[Mayson]

You're right, I'm mostly the latter. I recently got a degree from the college of electrical and computer engineering from the university of Illinois, and I can't find a job so I'm just sitting around with a lot of time on my hands

 

[Mayson]

Well... I said one big piezoelectric crystal and one big capacitor, but who's to say you can't use a bunch of smaller ones?

 

[mtn26bkr]

the energy created at best is zero because of having to cycle it to maintain all the processes

also the energy needed to keep the metal plates as frictionless as possible and very small distances apart would take away from any energy created

 

[Mayson]

That'd be awesome if you could prove it to me mathematically so I could be sure. Everything they've always taught me in classes seems to say you're right, but there's something about it that's nagging me.

It seems like if you had a mass on the end of the spring and let it drop... it'd occilate for a while, but eventually stop due to the energy lost each time. But if you continued to move your hand up and down at the resonant frequency it would move forever. With the little "machine" I designed you keep getting a "boost" due to the casimir force pushing at the "resonant frequency" of the machine if it was designed that way. Also, after reading up on it some more it seems that at seperation widths greater than 1um you get a bigger "push" together due to thermal fluctuations. furthermore, there are two forces that depend on the seperation being at "cavity-resonance". At a cavity-resonance frequency the radiation pressure inside the cavity is stronger than outside and the mirrors are therefore pushed apart. Out of resonance, in contrast, the radiation pressure inside the cavity is smaller than outside and the mirrors are drawn towards each other. Since, in reality, the attractive force beats the repulsive force we could have two mirrors at the cavity-resonance seperation which would cause them to move in and generate your current. Due to the repulsive force that gets bigger when you're out of "cavity-resonance" you wouldn't have to generate the same amount of energy to push them apart. You'd get some extra help from the casmir repulsive force and from the fact that on charged plates the force generated is WAY stronger than the casimir force.

I can see you starting out with a device manufactured to start out with a speration greater than 1um and at "cavity-resonance" so you get a big push together and generate some current. Then, once they move in together, your plates get charged and the respulsive force from the charged plates at such a close distance is enough to beat out the casimir force. Especially since now, at the closer distance, the force pushing them together from thermal fluctuations disappears at distances less than 1um and and now that we're out of cavity resonance we have less casimir force pushing inward. Also, we have momentum to help carry the plates back over the 1um seperation mark.