Why do we assume that zero point energy is infinite?

This is hearsay. Please state who has been saying what exactly.

 

This sounds like something out of one of those 'free energy' sites. Look, not everything you read on the internet is true :) That statement is not only wrong, it's crazy.

 

This is the usual mashup of science and fantasy that is pseudoscience. Blame your sources, not us, and get the clue that if "it's not backed up" it ISN'T SCIENCE.

 

It's a consequence of Quantum Field Theory:

It hasn't been experimentally verified that I know of, but I think most of you are misinterpreting it. It's not energy that can be used to do work. Remember that only differences in energy are measurable.

Read the two sections of the wiki here for more:
http://en.wikipedia.org/wiki/Zero-point_energy#Gravitation_and_cosmology

"Naively, it is infinite, but only differences in energy are physically measurable. The infinity can be removed by renormalization. In all practical calculations, this is how the infinity is handled. It is also arguable that new physics takes over at the Planck scale, and that the energy growth is cut off at that point."

Free Energy Devices:
http://en.wikipedia.org/wiki/Zero-point_energy#Proposed_free_energy_devices

 

...Unless you consider the possible role in universal expansion. Anyway, there is a vast difference between the scientific QM concept of the Quantum Vacuum and its many properties (expectation value, polarization, etc), but "zero point energy" is really just pseudoscience, which is why it is tied to "free energy devices". Perturbation of the vacuum may drive universal expansion, but as you say, it's not energy that is open to use on a lesser scale.

 

No, zero point energy is a well defined scientific concept. It is the intrinsic energy of a quantum system that is not accessible to do external work. Don't let the kooks take ownership of this concept ... it is the idea of harnessing ZPE to do work, not the concept itself, that is crazy-talking pseudo-science.

 

I am yet to encounter a situation where using the term "zero point energy" doesn't make the kooks yodle like madmen, and the scientific bunch flinch a little. I know you're right, but in practice it's hard to lead with what sounds (these days) like the opening of "The Secret Part 2: Cold Fusion In Your Pants!"

By the way, I just read a SciAm article in which the author (a psychologist) termed the Default Mode Network (neurological term) of the brain to be its "Dark Energy" which was, and I quote now, "With a nod to our Astronomer colleagues, our group came to call this intrinsic activity the brain's dark energy, a reference to the unseen energy that also represents most of the mass of the universe."

Shoot me now. *groan* No term which is open to popular culture is a safe term to use anymore. :(

 

Zero-point energy is not "really just pseudoscience". We didn't call the ultraviolet catastrophe pseudoscience, either, even though it led to infinite energy. What we do is find where the misconception is. It's the theoretical result of as scientific theory.

Also, relevant to the title of this thread, we don't actually assume infinite zero point energy. It's a result of quantum field theory. I.e., it's a result of our assumptions. That would be a rather weird assumption to start off with.

The people claiming that they can make free energy devices from the zero-point energy are the ones to be wary of, not the idea of zero-point energy itself.

 

Yes - ZPF is not psuedoscience. It has experimental varification as well, such as the positive and negative attraction of the Casimir Force.

 

i think ZPE is in harmonic oscillator..but in a rigid rotator there is no ZPE..is this correct?

 

1) There is another explanation by Lifgarbagez and Pitaevskii of the Casimir effect in terms of van der Waals force. References are on the wikipage by the way. Please keep in mind that van der Waals forces are well established.
2) Even if there was no other explanation, the tiny effect of Casimir requires for its measurement to spend quite some amount of energy in various cooling of the plates. No experimental device could use the Casimir effect to produce free energy.

 

Yep, all Casimir plates prove is that lower regions of energy density OR van der Waals forces are at play. Geckos don't need ZPE machines after all! :rofl:

This is why I said earlier that the TERM "ZPE" is often used in reference to the idea of EXTRACTING energy to do Work, not the existence of it.

 

I've heard of this other explanation. I'm waiting for it to catch on with the academic comminuty, if you don't mind. I'll, sick to the ZPE, the same thing predicted to exist before the observation of the Casimir Force.

 

Sure, it's up to you. But I'd be interested to know who it is you call "academic community". Is MIT good enough for you ? There are quite a few professional researchers on this very forum who like van der Walls and would call Lifgarbagez "academic".

Casimir effect and the quantum vacuum
Phys. Rev. D 72, 021301 (2005)

 

Right now, the scientific community has a greater stance on it being the ZPF. Until that dissipates, i will not believe it.

 

I do not think your answer is very interesting, as it does not even address who you call "the scientific community". But I agree that there is an academic debate. I'd just be interested if you could instead share references. For instance
The Casimir force between real materials: experiment and theory

Casimir energy, dispersion, and the Lifgarbagez formula

 

You want papers? Anyone can surf the net for papers on the ZPF - i am assuring you, the papers you follow are not widely-accepted.

 

Well it's better than nothing. The people I quoted where invited speakers in the plenary session at the international conference "60 years of Casimir effect" in 2008. In fact, Milton (second paper) even gave the opening talk. Bob Jaffe was formerly director of the MIT Center for Theoretical Physics.

 

Yes... and I agree with that... BUT... SO what? Science isn't done by a poll; the issue is that more than one explanation exists which cannot be ruled out. The community ACCEPTS both possiblities if it's smart.

 

ManyNames, I am afraid you are simply incorrect. It is part of the standard grad school treatment of advanced QM to show how you can derive the Casimir effect as a boundary value problem as well as a truncated vacuum problem. This is conceptually no different than being able to solve a freshman mechanics problem by either kinematics or conservation of energy.

However, since there are ways of looking at this that do not involve vacuum energy, I would be careful about what inferences I make about vacuum energy from this.

In case you didn't know, Lifgarbagez and Pitaevskii wrote a number of texts that have become more or less the standard grad curriculum in the Eastern Bloc, and are often used in the West. As has been pointed out before, Bob Jaffe was director of CTP at MIT, and that paper has dozens of citations.

 

Technically though, the Casimir force is the Van der Waals force and we can use the quantum vacuum to explain the Van der Waals force (as shown in Jaffe's reference of how Milonni pretty much rederives everything via the vacuum). And around and around we go. I do like Jaffe's paper though and I think his mention of Schwinger's work and the Feynman diagrams are of more interest.

 

I agree, and Milonni's book on QED and the vacuum is one of my favorite. It contains numerous examples of different calculations with different underlying interpretations leading to the same quantitative predictions, depending on when they were derived. His discussions of Bohr's original calculations for instance are quite revealing. I think such an approach is very interesting.

 

The zero point energy is fact and is the result or the uncertainty principle.Sir Fred Hoyle would look at these as micro bangs and dark energy is inflation.The energy is obtained from the energy lost from matter and spacetime that is accelerated to the speed of light at our universes event horizon spacetime of the large scale is curved back into the quantum realm.

 

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I know I love Milonni's book too. Squeal! Actually I think I sometimes find his book too interesting because it ingrains into the mind the quantum vacuum as being the answer for everything.

Figuring out where the Casimir effect comes from can become rather circular though. A lot of the different ways that you can use for the calculation all go back to the quantum vacuum and its fluctuating fields. We can calculate the virtual photon pressure, the change in the vacuum energy by using path integrals, Maxwell stress tensors, or integrating over the possible modes. Schwinger has his rather incomprehensible source theory. You can derive it from a relativistic retarded Van der Waals force. But almost all of these still have the quantum vacuum in some underlying principle. That's why I like Jaffe's paper because he helps to explicitly state the non-vacuum formulations.

The vacuum energy is not fact. We treat it as theory but it has not been experimentally proven. Fact is, as previously stated, the vacuum energy could be renormalized to be anything and it would not affect the physics of the problems because the behavior that arises is due to the changes in the vacuum energy itself. The energy in the vacuum doesn't have an origin, it is the consequence of the fact that the electromagnetic field operators in quantum field theory are harmonic oscillators. The ground state of the fields, while having zero mean field amplitudes, has non-zero energy.