Hot answers tagged casimir-effect
5
Although, I do not know if a general proof exists, I think that the Casimir
effect of a renormalizable quantum field theory should be completely
understood by means of a theory of renormalization on manifolds with
boundary. The key feature is that one cannot, in general, neglect the renormalization
of the coupling constants in the boundary terms. Using this ...
4
The objects whose number is lower in between the plates are not really particles per se but the different modes - different possible values of the wavelength or frequency, in particular - in which the particles may be created.
If the distance of the parallel plates is $L$, then the electric field has to vanish at the boundary between the vacuum and the ...
4
Ref [19] in the arXiv paper, C. M. Caves and B. L. Schumaker, Phys Rev A 31, 3068 (1985), gives a clean description of a parametric amplifier as the prototype of a two-photon device, at the bottom of its second page:
In a [parametric amplifier], an intense laser beam at frequency
$2\Omega$ —the pump beam— illuminates a suitable nonlinear medium. The
...
4
The reason why the Alcubierre drive is not feasible as an FTL drive has nothing to do with absence of exotic matter; in fact, we likely had plenty of the required matter during cosmic inflation era, or something with identical geometrical effects. Physicists that dismiss it as impossible because "there is no exotic matter" play ignorance to the fact that ...
3
I don't think the formation of lipid bilayers is analogous to the Casimir effect because it's a surface energy effect. However there is an effect called depletion flocculation that is very closely analogous. This happens in a polymer solution when surfaces approach more closely than the size of the polymer molecule. The polymer is excluded from the region ...
3
Thank you for your interesting question. The following is what I assumed in the paper. If you accelerate to the right, the Rindler horizon to your left is a boundary beyond which things are in principle unobservable for you. So, as soon as the nearer Rindler horizon forms, the far cosmic horizon behind it becomes unobservable and therefore (following the ...
3
The Casimir effect is analogous to gravity in only one way--- it has a negative energy which varies as a power of the distance. In all other ways, it is different. The power-law is different, the cause is different, it is a quantum effect, not a classical effect, and the mediator is the electromagnetic field, not the gravitational field.
Negative energy is ...
3
The Casimir effect and the Van der Waals force between two conducting plates are one and the same thing.
To see this, consider the boundary conditions postulated for the Casimir effect. The electric field has to be exactly zero at the plates. Because of this, it is said, the zero point energy of the vacuum is lower in between the plates than outside, which ...
2
Dear Carl, the correct paper to derive the 0.1-second lifetime of the anti-Hydrogen atom in the gravitational field is described after the very sentence you quoted.
There is a "[20]" symbol which means that the sentence is justified in the reference number 20 in the list of literature at the end of the paper you quoted. So the correct paper that answers ...
2
A friend recently brought to my attention that this experiment was actually performed 6 months after i posted the question in this site:
http://blogs.nature.com/news/2011/11/light_coaxed_from_nothingness.html
http://www.chalmers.se/en/news/pages/chalmers-scientists-create-light-from-vacuum.aspx
Christopher Wilson from Chalmers (and his team) used the ...
2
Virtual particles influence physics at every point of space, whether or not there is a nearby atomic nucleus or orbital. All electrons in an atom receive energy shifts analogous to the Lamb shift (from virtual photons), aside from other quantum corrections. In fact, the influence of the virtual particles only becomes truly measurable if there are some nearby ...
2
The zero-point energy for the quantum mechanical harmonic oscillator can be related to the Heisenberg uncertainty principle (HUP). A bit oversimplified, the point is intuitively that if the mechanical energy
$$H~=~\frac{p^2}{2m}+\frac{1}{2}m\omega^2 q^2, \qquad \omega ~:=~ 2\pi f,$$
is zero, then the position $q$ and the momentum $p$ must also both be ...
2
I think you are confusing the CMB with radiation from the apparent horizon. CMB is just relic light from the surface of last-scattering - it behaves like any light which is emitted from a source. It is totally unrelated to the Hawking radiation emitted from the horizon. A neat coincidence (as afar as we know) is that the surface of last scattering is "close" ...
2
The interaction between the geometry of spacetime (how precisely it is "warped"), and energy, is a fundamental notion in general relativity. Specifically, the Einstein field equations tell us that if there is energy or momentum near some spacetime point, then the geometry nearby will bend (warp, curve, whatever you'd like to call it) in a particular way. ...
2
The energy density between the Casimir conductors can indeed be positive or negative. The calculation of Casimir energies is often done by noting that the plates impose boundary conditions on the field modes that can exist between them. Therefore in the presence of the plates, a more restricted set of modes is allowed than would be the case if the plates ...
1
When you have two parallel mirrors you get standing waves between them, and the standing waves can only form if the spacing between the mirrors is a half integral number of wavelengths. Exactly this principle is used in the Fabry-Perot interferometer. The restriction of the wavelength happens because if the mirror spacing is not a half integral number of ...
1
I'm happy to see that Mike himself has replied to the question (being him the author of the paper in question, and the inertia-as-a-cosmological-casimir-cutoff effect idea), but i wanted to underline a few items.
A derivation of a MOND-like acceleration cutoff for inertia as proposed by quantised inertia using heuristic by physically sound arguments, which ...
1
It's associated with the confinement of the particle. As the coefficient of the quadratic term in the harmonic potential goes to zero, the particle becomes less & less localized and the the zero point energy drops accordingly. It can be as small as you want.
When you speak of photons, now you're referring to QFT and the energy in a mode of the EM field. ...
1
All interactions at the quantum dynamical level are subject to an analysis with Feynman diagrams, and the Casimir effect is not different in this case. Virtual pairs are internal lines in Feynman diagrams.
R.L.Jaffe has a arXiv paper that goes into the detail on the Casimir force and corresponding diagrams.
the abstract:
In discussions of the ...
1
The problem is not the availability of exotic matter. It is the manipulation of it in a practical manner that is not known. The stuff of exotic matter (quantum fluctuation) is everywhere. The Casimir Effect is only a demonstration of its existence in a practical manner. To do more with that so called negative energy that the quantum fluctuation can present ...
1
Virtual particles are mostly the name given to a category of mathematical expressions (contained in Feynman diagrams). While virtual particles are mathematically associated to real, physical particles (virtual electron, etc.), they have no reason to exist physically. Essentially, the name is a somewhat of a misnomer.
Now, there is a point of view in which ...
1
Casimir force is an effect of interaction of two neutral but quantum mechanical plates. Neutral means they are not globally charged. Quantum mechanical means they consist of many real particles and fields bound together with laws of quantum mechanics. When people use the conditions of ideal conductivity of plates and write the filed boundary conditions like ...
Only top voted, non community-wiki answers of a minimum length are eligible
