Bob_for_short

An external field makes any bound electron oscillate according to this field, OK? When the field is resonance for a given transition, the transition happens most likely in phase. There are other transitions - with different directions but they are suppressed. In absence of an external field the atomic radiation is spontaneous - in all directions. Mathematically you can consider a population of photons in a given state N(k,t): with time it grows to finally describe a radiated photon. In an external resonance field there is an additional "pumping" term that increases the rate of population of the coherent states and suppresses the non coherent ones.

>what is the force carrier in this situation? It is the same as in case of two neutral atoms at long distances, nothing else.

Zero Kelvin makes perfectly sense for all of us but you.

The Casimir effect can be understood as a kind of Van der Waals force which is more physical than "vacuum fluctuation" in a "free" space. In fact, it is an interaction of neutralized charges at a distance. The charges are never free from the quantized EMF. I would say, the quantized EMF is a property of each charge. Thus the (neutralized) charge potential interaction at long distances is an interaction of compound systems, just like atom-atomic interaction at long distances (Van der Waals or so). Look at an atom (of Hydrogen, for example). The electron is bound to a nucleus. We can speak of electron fluctuations in the whole space but it is not possible without an atom. The vacuum here is just the atomic ground state. The same is valid for the quantized EMF - its "fluctuations" are not possible without a charge so no virtual particles are present in an empty space without a charge.

Yes, one does. The problem is in impossibility to physically create such a non-compressible stick. Physycally you create a sound wave or a shock wave in the stick to start moving the other side.

The vacuum is a stationary state with a certain (the lowest possible) energy. There is no energy fluctuations here, there is nothing to harness.

Any energy is a capability to do some work, so the energy exchange is essentially involved in this definition. Also, there are many energy forms and the energy conservation law means the equal energy transfer from one form to another.

Of course! Any potential exceeding the particle kinetic energy is "reflecting" for the particle. In particular, in accelerator physics for electrons there is a notion (an effect) of a virtual cathode.

In QM and QFT the vacuum is just the ground state of a compound system. If there is no system, there is no vacuum.

I agree. That is why I prefer more realistic analogies or explications. Look at the original post: "Virtual particles wink into existence throughout all of space." It is just wrong but commonly accepted. Now look at an atom (of Hydrogen, for example). The electron is bound to a nucleus. We can speak of electron fluctuations in the whole space but it is not possible without an atom. The vacuum here is just the atomic ground state. The same is valid for the quantized EMF - its "fluctuations" are not possible without a charge so no virtual particles are present in an empty space.

It depends on derivation. The Casimir effect can be understood as a kind of Van der Waals force which is more physical than "vacuum fluctuation" in a space. Merged post follows: Consecutive posts merged This is the most misleading analogy. The water waves are external here. With the same success you can use the gas pressures inside and outside of some "bottle". Uncertainty principle is a vague "explication". The spectrum exclusion is an idealization. In fact, it is an interaction of neutralized charges at a distance. The charges are never free from the quantized EMF. I would say, the quantized EMF is a property of each charge. Thus the (neutralized) charge potential interaction at long distances is an interaction of compound systems, just like atom-atomic interaction at long distances (Van der Waals or so).

Yes, it does. Time intervals are relative, space distances too, the intervals are invariant.

Everything was defined above: L is a distance, S is an interval.

In a moving reference frame you will observe everything moving really fast, like in a car in a city. There are the reference fames moving at the speed of light V_rf = v_light = c/n < c in a transparent medium, and there are even faster than that (but of course with V_rf < c).

That may explain the resulting barion asymmetry!

Yes, the time intervals (t2-t1) and distances or lengths L are not invariant - they change from one RF to another, but their combination S^2 = L^2 +[i*c(t2-t1)]^2 is invariant in our world. Here c is just a numerical constant common to all RF. In this sense x4 = i*ct is a forth independent variable (1D distance) in a four-dimensional (Minkowsky) space.

Outside this point there was nothing, just empty dark (black) space. Then it was gradually filled with matter.

Time is time, it is not a forth space dimension in a usual sense. In a usual geometry there is a notion of distance L=|r1-r2|. It is numerically the same (invariant) whatever reference frame you use. In reality it is not invariant - it depends on the reference frame. The invariant quantity is the so called interval that includes time. In this sense it serves as a forth coordinate r4=i*ct in a four-dimentional space (r,i*ct). It was described for the first time in a H. Poincaré's paper (1905) and extensively applied later on in Minkowsky works. On a two-dimesional plane (x, i*ct) the inter-axe angle is still 90° and the Lorentz transformations are just rotations in this plane that preserve the "length" determined as S=√[x^2+(i*ct)^2].

You can visualize the photon wave as a classical wave but you have to keep in mind that it represents the probability amplitude, not the real amplitude. It belongs to many-many separate one-photon experiments or to one experiment with many-many photons, whatever. The main point is that the probability is meaningful for many events, not for one.

Photon is not a particle, it is a wave. For a wave to propagate it is important to take correctly into account all obstacles (double- or multiple slit screen). The interference pattern is obtained as result of many photon hits. The notion of probability belongs to the whole set of hits. The wave function, as a probability amplitude, belongs to the whole set too, not to one hit.

There is no such a thing as a half of photon. Photon carries energy, and a half of energy is not observed. Dirac states the experimental facts. The first mentioning that I know about interference of a photon with itself was made by H. Poincaré in his "Last Thoughts" (1913), as a logical consequence of a quantum nature of light and low intensity regime of interference.

I see many visited but few left their answers. I think it's guests, not members so they could not participate. If you are a registered member, don't be shy, vote - this poll is anonymous anyway.

How can we reply to your question if the Wikipedia article is a stub and no other information is available?

[math] \frac{g_{\rm th}-2}{2} = 1159652140(28) \times 10^{-12} [/math] In some simple cases of the perturbation theory, like in http://arxiv.org/abs/0906.3504, page 6, the relative accuracy can be better even in the third order.

If you know what the geometrical optics is and how it is obtained from the wave equations, then it is easy to understand the de Broglie idea that the electron is also a wave with short wave-length, so it is often seen as a particle with a certain trajectory but in fact it is a wave spread in space and the Schroedinger equation is the corresponding wave equation.