Zero Point Energy: WTF!

[Diogenes_of_Sinope]

Take a look at this vid (all of you with 1 hour+ free time, that is), and post your opinions... http://video.google.com/videoplay?do...5057&q=quantum
It basicly shows that we (probably) all live in in a sea of energy (for astronomers that'd be dark matter, I guess) and that you could extract some of that energy to use as you wish, 'seemingly' violating the first law of thermodynamics (conservation of energy) ...weird stuff, really

[bdh]

Take a look at this vid (all of you with 1 hour+ free time, that is), and post your opinions... http://video.google.com/videoplay?do...5057&q=quantum
It basicly shows that we (probably) all live in in a sea of energy (for astronomers that'd be dark matter, I guess) and that you could extract some of that energy to use as you wish, 'seemingly' violating the first law of thermodynamics (conservation of energy) ...weird stuff, really

Its all nonsense. His entire premise is that energy isn't conserved on a quantum scale, which there is absolutely no evidence for.

[chris_uk_83]

I've not had time to watch the video yet since I'm at work and while I can get away with posting on this forum pretty much all day I think watching a video might not go down too well!

Anyway, zero point energy.

Zero point energy is in no way related to dark matter/energy; we know precisely what zero point energy is and we have no idea what dark matter or energy are, don't confuse the two. It's plausable that neither dark matter nor dark energy exist at all and it's our model of astophysics and cosmology that's up the wall :p (that's an invite to cosmologists to argue that point).

So, what is zero point energy? It's a horrendously complicated thing to understand without a grounding in reasonably advanced quantum mechanics, but I, being the kind chap I am, am going to attempt to at least describe it in layman's terms. Right, everyone knows that kinetic energy equals 1/2 times the mass of a body times the square of its velocity right? Therefore any moving body has energy. Ok, now we also know that in atoms, electrons orbit a central nucleus. In this case, if an electron is in orbit round a nucleus it must have some kinetic energy. The faster it goes and therefore the further out from the nucleus it is, the more kinetic energy it has, similar to swinging a ball round your head.

Quantum mechanics says that there is a minimum possible orbit for any electron in an atom, this is known as its ground state. Since, even in the lowest possible orbit, the electron is still moving, it still has energy. This energy contributes to the zero point energy of the system. Good luck extracting this energy though!

That's a very basic overview of zero point energy, and it's an awfully incomplete picture but, with any luck, it should give an idea of what's going on.

Incidentally I know most people don't trust Wikipedia as a reliable source of information, but in physics related matters it really is absolutely brilliant. I think this is because nobody except proper physicists either cares enough to write inaccurate articles, or simply can't make them seem convincing :p. Try this article if you like, but don't expect to understand it unless you're a physics undergrad

[chris_uk_83]

Bah, double post. Sorry. Admin pls remove.

[Diogenes_of_Sinope]

Thanks man, i haven't read the article yet (i will tomorrow ), but asides from the ground state you mentioned, in the vid the guy (a prof.) says that zero point energy contributes to the strange phenomenon that occurs when you try to freeze helium: it doesn't want to. now to be honest he said that it wouldn't freeze at fractions of a degree Kelvin so the phase change could still happen it is just terribly difficult to get close to 0 Kelvin and impossible to get there at all. so bla bla sorry what i meant was: he said that maybe zero point energy is what's keeping helium liquid from becoming solid and that there are ways of extracting this energy in rather small amounts (i think he was talking about microscopical scales, not even nanoscale) but if done in parallel one could both cause motion and store/use energy (experimentally) in practical (big) amounts. hmmm i'm not being very lucid (sleepy) sorry. he also said that inertia and gravity could have something to do with this energy. i still need to wiki a few terms like 'casimir effect' and 'vacuum fluctuation' but this certainly sounds interesting... take a look at the vid when you get home, Chris. then tell me what you think of it.

[bdh]

says that zero point energy contributes to the strange phenomenon that occurs when you try to freeze helium: it doesn't want to. now to be honest he said that it wouldn't freeze at fractions of a degree Kelvin so the phase change could still happen it is just terribly difficult to get close to 0 Kelvin and impossible to get there at all.

Its not true. Helium does freeze, except you also have to add pressure in addition to low temperatures.

there are ways of extracting this energy in rather small amounts (i think he was talking about microscopical scales, not even nanoscale) but if done in parallel one could both cause motion and store/use energy (experimentally) in practical (big) amounts.

By definition, zero point energy can't be extracted. Its the minimum amount of energy. In order to make it move from one place to another, you have to gnerate an area with even less energy than zero point.

[chris_uk_83]

Now helium is something I do know about, having worked with the stuff (helium 4 anyway) throughout my Master's. At atmospheric pressure helium doesn't freeze. To understand why, we need to know what happens when things do freeze. The atoms within materials vibrate all the time, in liquids and gasses they vibrate so fast that they move around all over the place. Cooling the material slows its atoms down (removes energy) enough for the atoms to get close enough together to form bonds. These bonds give a solid its rigidity.

So, in order for a solid to form, its constituent atoms have to have less energy than the attractive force between atoms (which will prevent them escaping each other's clutches).

In helium the zero point energy is relatively high (for its size) due to its low atomic mass. This keeps the helium atoms reasonably energetic even at absolute zero (since zero point energy is the energy an atom would have at absolute zero). Also the Van der Waal's force (think electric repulsion) between the atoms push them away from each other. These two effects prevent the helium atoms from getting close enough to each other to form a solid and thus freeze.

As bdh says, if you put the helium under enough pressure and low enough temperature (see this phase diagram) you can freeze the helium. This is because there is an additional force due to the pressure pushing the atoms together.

Unfortunately I still haven't had time to look at the vid, but I may this lunchtime if I'm lazy enough not to go to the gym. I do know that a LOT of people have tried to harness zero point energy in some form or another, people have been attempting to build perpetual motion machines for hundreds of years. Wikipedia even informs me that NASA and BAe are working on a propulsion system that uses zero point energy to power it. I don't know how much I believe this though since there is no citation to follow up.

I have learned though that in physics you should never say never, because chances are that someone will come along and do the impossible one day!

[chris_uk_83]

WTF? Double post again?

[chris_uk_83]

I think he was talking about microscopical scales, not even nanoscale

Just to clarify, nanoscale devices are 1000 times smaller than micro-scale devices. It all comes from the latin prefixes for numbers:

Tera = 1,000,000,000,000
Giga = 1,000,000,000
Mega = 1,000,000
Kilo = 1,000
no prefix = 1
milli = 0.001
micro = 0.000001
nano = 0.000000001
pico = 0.000000000001

[Town Watch]

isn't there something like an attosecond? so atto would be the smallest pre-fix?

[Simetrical]

Its all nonsense. His entire premise is that energy isn't conserved on a quantum scale, which there is absolutely no evidence for.

Energy is conserved on a quantum scale, but only (to my understanding) on average, not necessarily in any particular case. That doesn't mean it's possible to leverage energy out of this fact, of course.

[chris_uk_83]

@ Town watch

Yep, these prefixes just keep on going as far as I'm aware. In standard form there are 20. This website lists them all.

@ All

I've now watched the video. What he says seems to make sense, although I would like a little more explanation than he gives: he cites experiments and theories without going into detail, which is fine for the audience he is addressing. I went to have a look at some of the papers he cited, but unfortunately I haven't got access to Phys Rev Lett B any more . The experiments do exist though, and it would seem that through clever manipulation of the Casimir effect you may be able to 'fool the universe into giving you its energy'. I'll wait and see to find out if anyone manages it though!

I'd urge anyone who automatically says "this breaks the conservation of energy law, therefore it must be wrong", to actually watch the video and then look at some of Tom Valone's citations for further reading. This looks potentially plausable to me, but I'll wait and see if it's ever achieved.

[Simetrical]

People should keep in mind that the law of conservation of energy is an empirical fact, not an absolute fact. It can always be falsified (which is what makes it empirical). But given the number of quacks who claim to have broken it, I'll believe it when I see it, that's all.

[Beiss]

Totally WTF.

[chris_uk_83]

Right, Beiss, if you're interested I can have a shot at explaining how we might draw energy from the quantum vacuum (zero point energy) using the Casimir effect. It'll be long and I'll have to think about it so it'll be done only when I have time (most probably Tuesday) and if anyone actually cares

[chris_uk_83]

Right, sod the lot of you I don't care if anyone wants to know about this or not; I'm writing it

The Casimir Effect

We all know, don't we that even a perfect vacuum isn't actually completely empty: it still contains lots of particles which keep spontaneously coming into existence and annihilating with each other and disappearing again. This is fine according to Heisenberg's Uncertainty Principle , which states that the uncertainty in energy in a system, multiplied by the uncertainty in time is less than or equal to Planck's constant divided by 2.



Basically this means that you can borrow an amount of energy (delta E) from the universe as long as you pay it back within a certain time (delta t). As mass is related to energy by E = mc^2, you can create mass out of "nothing" as long as that mass is taken away again before the alotted time has elapsed. Generally though, photons are created, which are massless, so you don't need E = mc^2.

Right, now we've established that a perfect vacuum isn't, we can move on to radiation pressure. We know that pressure is exerted by liquids gases and solids, and that it happens becasue they push on surfaces. This push (at least in gases) is caused by the gas molecules banging into the sides of the container. The hotter the gas, the faster the molecules move and the higher the pressure. Well the same thing happens with light (and any EM radiation (photons)). If you shine a light onto a reflective surface, the photons will be bounced off and will exert a pressure on that surface (through a different mechanism than simply bouncing, but that's too complicated for this explanation and 'bouncing' is an adequate analogy). This pressure is tiny compared to gas pressure but it is finite and measurable.

We also know that photons are essentially light, and light travels as a wave. Waves have wavelength and frequency, therefore a photon has wavelength and frequency. We can determine the wavelength of a photon using the formula E = hf, where h is Planck's constant, E is the photon energy and f is it's frequency. Frequency is related to wavelength by f = c/λ, where c is the speed of the photon (the speed of light) and λ is its wavelength.

Therefore, high energy photons have short wavelengths and vice versa.

Now, what happens if we bring two mirrors very close together in a vacuum? Well, you have to bring them closer than the wavelength of the photons produced for anything to happen (around a few hundred nanometres). When you do though, there are certain wavelengths that resonate within the cavity you've produced (remember, all wavelengths are being constantly produced and destroyed) this depends on the separation distance of the two plates. These photons bounce back and forth a few times and can cause interference , constructive interference will increase the radiation pressure between the plates, destructive will reduce it. The wavelengths that are too long to resonate will be excluded entirely.

Conversely, photons of all wavelengths are impacting on the outside of both mirrors at all times. This has the effect of producing an attractive force between the mirrors. Really, they are being pushed together since the radiation pressure on the inside is less than the radiation pressure on the outside. Remember that you have used no energy to cause this attractive force.

By changing the shape of the mirrors (for example to an enclosed sphere) it is possible to make the force repulsive. In this way you can imagine your own ways to harness this energy. I don't think it's been done yet, but some bloke called Pinto is currently working on building an engine to extract vacuum energy!

[Manji]

I'm not disagreeing or anything, just trying to understand this bit:

We all know, don't we that even a perfect vacuum isn't actually completely empty

Well, I've read that a perfect vacuum with a gaseous pressure of absolute zero is in fact absolutely devoid of any matter and (according to quantum physicists) impossible to reach/replicate. More, vacuum as we know it is merely partial vacuum and it's measured by how closely it approaches a perfect vacuum.
Now, the question is, why?
Zero-point energy, if we consider it to be "the lowest possible energy that a quantum mechanical physical system may possess and is the energy of the ground state of the system." would be a energy source possible, provided we had the technology for it, to be tapped and used but time and time again efforts to achieve that have been unsuccessful.
If indeed zero-point energy is energy why can't we create or even theoretically design a "free energy" device? (and I'm not talking about energy conversion or energy output just a device to maintain and control zero-point energy.)

[Diogenes_of_Sinope]

Dude, thanks for the explanation. i still don't fully understand it but i'm not completely lost as before when talking about the casimir effect!
Anyway i'm still lost as to how to REPEATEDLY extract energy from that pressure; to me it still seems like going underwater with an empty cilinder that has a piston on one side linked to a dynamo, the exerted pressure will cause the piston to move towards the inside of the cilinder and that motion can drive a dynamo to produce electrical current... now once the cilinder closes the effect is gone and you have to withdraw the piston (which takes just a little more energy than it delivered when it closed, btw) to start over. how's that different from radiation pressure? what i mean, is that pressure is a force induced in one direction, like gravity and therefore useless as an energy source unlike heat which which exerts force in all directions and therefore can repeatedly be used used and converted into other kinds of motion (energy) not just that one time... how exactly could pinto be able to do it, then? i know i must be looking at it the wrong way, so chris could you explain?

[chris_uk_83]

@Diogenes
You're absolutely right, if that was all that was going on then yes, it would take more energy to separate the plates again. What is actually being tried is slightly more subtle and involves lasers stimulating one of the mirrors to change its electric field or something. It's being done by a bloke called Pinto and I can't find the paper on it (which is massively annoying becasue I wrote down the reference and lost it), if anyone watches the video again can they find me the reference to Pinto's free energy machine please? It's Phys Rev Lett B ?????? If I get that I'll have a shot at explaining what he's trying to do.

@Manji

Zero-point energy, if we consider it to be "the lowest possible energy that a quantum mechanical physical system may possess and is the energy of the ground state of the system." would be a energy source possible, provided we had the technology for it, to be tapped and used but time and time again efforts to achieve that have been unsuccessful.

True, but there are slight subtleties when talking about zero point vacuum energy, subtleties which I don't fully understand, but give rise to the Casimir effect, which they are trying to harness.

Perfect vacuum is an odd term, and you may be correct about a completely perfect vacuum with zero vapour pressure being totally empty (I'd like to see your source for that, rep if you do for teaching me something), but realy vacuums are a veritable sea of 'virtual' particles popping into and out of existence constantly.

We can design a theoretical free energy device and it has been designed, now it's being built and as I mentioned ealier I would like to see the paper on it to ascertain how and whether I think it'll work or not. Chances are it won't, but we can dream !

[Manji]

Perfect vacuum is an odd term, and you may be correct about a completely perfect vacuum with zero vapour pressure being totally empty (I'd like to see your source for that, rep if you do for teaching me something)

Poincaré Seminar, Duplantier, B., & Rivasseau, V. (2003). Poincaré Seminar 2002: vacuum energy-renormalization. Progress in mathematical physics, v. 30. Basel: Birkhäuser Verlag.

also:
http://www.npl.co.uk/pressure/faqs/vacuum.html

Though the term itself, "perfect vacuum", is used in many other sources and accredited as being the theoretical (and according to quantum physics impossible) state of vacuum where no matter would be present and used as reference when defining pressure range to degree of vacuum.