Bob_for_short

If we suppose that the electron is not point-like but smeared classically or better quantum-mechanically, what model would you experts prefer: a "rigid" or "soft" electron? I do not speak of the Lorentz contraction here, I speak of "mechanical" behavior in collisions.

The static gravitational attraction of the plates was calculated and found to be negligible. If you speak of gravitational vacuum fluctuations, their contribution cannot exceed the electromagnetic contribution because of too weak coupling constant involved.

It is so in atoms. Look at Hydrogen atom. Both the electron and nucleus "turn around" the atomic center of mass there. As the lectron is lighter, its orbit is larger in the ratio Me/Mp to the nucleus orbit size. In quantum mechanics instead of orbits there are charge "clouds" bu the size ratio is tha same. Another thing is in molecules and condensed (solid) state. There the nuclei oscillate around their equilibrium positions with much larger amplitude - it may attain the inter-atomic size. In a solid state the positive charge is also much widerl "smeared" than in an isolated atom, to be exact.

Yes, if the boson is real, not virtual. For example, if you go out of the room, photons miss you and hit the wall. A virtual photon is to a great extent a usual Coulomb interaction potential 1/|r1 - r2|. Whatever motion of particles happens, it remains a function of their distance. If one particle decays into another charge and a neutral piece, the Coulomb force will act between the new and the other charges.

I sleep and you all are in my dreams.

Right. It is the smallest charge that we can separate from a matter and operate with it - accelerate in accelerators, TV tubes, electronic lamps, etc. Quarks were invented (not directly observed) in order to: 1) explain some scattering experiments with heavy compound nuclei, 2) squeeze the quarks into a certain group of symmetry that require at the same time fractional charge of quarks (3 quarks in proton, neutron, and two in mesons) and impossibility to observe a quark in a free state. The strong interactions are so strong that one cannot separate things in a compound system without creating new coupled quarks. It is such a model in theoretical physics. Just keep in mind that strongly interacting things sometimes cannot be separated, like phonons from a solid. They are some quasi-particles - elementary excitations of compound systems. We can make proton beams that are beams of coupled together quarks. Quarks are always bound, mesons are well observed as free.

A pointlike charge creates an electric field that acts on other charges in a ceratin way E(r) = qr/r^3. This filed can be "felt" at many points at the same time by different other charges. Note that q can be of both signs and may belong to nuclei too. See the answer above. They are particular cases of charges. There are many other charged particles, heavy and light. Yes. If you srtip many electrons from a body, it gets positively charged due to non-compensated amount of positive charge of all nuclei and the amount of remaining electrons. This happens all the time when wind blows and separates charges between the Earth and clouds. Sudden recombination (neutralization) of separated charges is a lightning.

How do open strings look like? Like I- or like C-letter? Do they vibrate as a whole (left-right) or like S-letter?

Protons are charged. That means they are very sticky. You need a laboratory equipment to obtain a proton beam. Also you will not be able "to release" them in the air as if they were neutral. They will return to the negatively charged equipment. You have to make a closed circuit in order not to accumulate a positive/negative charge at some place.

The misleading part is not "virtual" but "particle" in the term a "virtual particle" (if we speak of the photon propagator). Well, I think we all expressed our positions. No need to repeat them.

I propose you to compare the photon's being near shell due to finite Earth-Sun distance and due to finite wave packet width. You will see that the latter will dominate. So the photon is real. Speaking of the tree-level calculation, consider an electron-proton scattering in QED. The energy momentum remains within the system e+p. Nothing is radiated in this approximation. It is quite different from radiation and absorption. Why to invent some "carriers of interactions" if they are not independent and do not exist? Besides, the real photon cannot be entirely absorbed with a free charge. So calling the Coulomb interaction a "virtual photon" is a bad habit. Calling the real photon a "virtual photon" is also a bad habit. I find this lagnuage extremely misleading. It is not admissible in exact sciences. Merged post follows: Consecutive posts mergedOne more argument in favour of photon's being real. While calculating we can have on the paper the "source" of the wave and the "absorber". So we can first find the radiated wave, its energy-momentum which are the source dependent things. Then we inject this solution into the absorber equation. In experiment we may not have an idea what the photon source is. We describe the measured photon flux as a free wave (which is a good approximation to the source-dependent wave solution at far distances). So we disconnect the source and absorber. This makes the radiated field real and propagating. It carries the energy-momentum itself. We can manage it: reflect, guide, irradiate our target with it. It is much more practical to think of it as of real field, don't you find it so?

I understand you. Unfortunately your language is wrong. A real photon is absorbed by my eye molecule and the molecule excitation is then transformed (dissipates) into an electric signal. Why do you need to call the photon a virtual one? Let us take a charged oscillator for simplicity. In an external plane EM wave it gets excited. If the wave is not limited in time and is a resonant to the oscillator, the latter accumulates the energy. Solve the corresponding classical equation with the following initial conditions: before t = 0 there is no filed, and after t = 0 the oscillator obtains an external periodic pumping filed: ma = -kx +eEsin(wt). If the wave is limited in time, the energy gain is finite. In case of strong external filed we say it is the field who makes the work on increasing the oscillator "internal" energy. Our mechanical equations are sufficient to calculate it. We do not calculate the external wave weakening as redundant. In case of one photon that disappears (a weak external field) we see the energy-momentum transformations: the field gets weakened and the oscillator gets excited. If the source of the wave is far away and neutral (no Coulomb tail exists), the processes of radiation and absortion are very separated in time so it is not a direct interaction between charges but emmission and absorption of real photons. In other words, the source loses the certain energy forever and it does not depend on whether the real photons are absorbed or not and where and when. Unfortunately in perturbative calculations they have admitted such a sloppines (emission and absorpion by itself, self-action) that confuses the real processes and the loose language of perturbative corrections. I am sure we can do without this language.

Wre can do without even mentioning the mass-shell constraints if we work in the coordinate space rather with the propagator Fourier images. Such a photon is, of course, free, as soon as it "leaves" the Sun. The Earth-Sun distance is much larger than the "photon size" - the length of its wave-tarin or wave-packet. It is never described as a photon propagator.

I avoid using the term "virtual particle". For me it is not a particle at all. Strictly speaking, a “virtual particle” is the corresponding propagator, nothing else. Physically it is a synonym of quasi-static interaction of charges. Giving an independent sense to “virtual particles” is unforgivable sloppiness. It does not create any insight but a great confusion. A real particle, a photon, for example, is indeed on mass-shell only approximately. It is, however, not because of its being “virtual” but because any photon has a limited wave-train (10000-100000 vibrations, for example). Thus it is a wave packet with slightly different frequencies. In many practical applications one does not care about it and uses E = hf, as if it were a one-frequency thing. I disagree with the sloppiness mentioned above. Besides, those variables of integration are dumb and independent. We denote them as “momentum” and “energy” and this is the cause of confusion. As soon as they are independent Fourier variables, there is no mass-shell relationship between them. It is natural. Finally, nothing is left after integration. So if we work in terms of final expressions, no notion of “virtual particles” appears. It is not really correct to imagine a point-like charge and its field as a real entity. According to the strict QED results, a point-like charge is an inclusive, illusory, approximate picture rather than the primary one. It is another subject. If you like, I can explain it in another thread. It is also better to imagine real processes - scattering, bound states, excitation and radiation of real QM systems. Then there no problems in description appear. For example, when one says that a charge is surrounded with a field 1/r, one always means that if you put another charge at r_2, their potential energy of interaction will be 1/|r - r_2| rather than 1/r + 1/r_2. What is counted is the interaction energy, not the "self-action" one. In your example you speak of the "self-field".

As I said previously, the magnetic field is a way to say that bodies interact in this or that way. One needs two bodies in order to describe (measure) the magnetic field quantitatively. So it is a long-distance interaction of bodies (charges). Often one speaks of magnetic filed itself, I admit, but anyway what is meant is interaction. For example, in magneto-statics one can express the current-current interaction without appealing to the notion of magnetic filed because the filed equations can be resolved and their solutions (fields) can be injected into the equations of motion of charges. So the charge interaction is described with their positions and velocities. The notion of fields becomes sensible while considering radiation of charges - the kinetic energy loss due to emission of EM waves, i.e., when the fields are real, not virtual.

Yang-Mills field is similar to the electromagnetic filed (there are filed tensions too) but it has more complicated (non-linear) dynamics. In electromagnetism the field depends on charges which depend on fileds (coupling fileds and charges). In Yang-Mills theory the Yang-Mills filed depends also on itself directly (together with dependence from charges). Renormalizations are discarding some terms in solutions. When one solves a problem by the perturbation theory, one obtains big corrections so one cannot make calculations. Sometimes some big corrections can be groupped with the mass and charge of electron. Then the whole group is called a "renormalized parameter" and the experimental value is assigned to the whole group. It is equivalent to discarding the perturbative corrections to the experimental (original) masses and charges. Doing so one obtains small corrections and finite calculation results. The latter may be fitted to the experimental data. It "works" in QED.

I disargee. It is quite clear question. Real photons are transversal. They are solutions of free equations. Their role is, rughly speaking, to get into the charge equation motion as external fileds. Photons cannot compensate each other. The electric and magnetic fileds of charges are not transversal. They are solutions of (often static) equations with sources. These fileds cannot propagate independently, theiy are "attached" to charges. In many cases they are compenstated: the negative and positive tensions cancel each other and we observe neutral non-magnetic bodies. The term "virtual particles" implies some propagation. In fact, it is just charge interactions without radiation: the energy-momentum in scattering is conserved without taking the radiation losses into account. Another thing - it is not physical approximation and it leads to IR divergences. So I think it is better to speak of real charges and their interactions without "virtual" particles. Anyway, static fileds are not virtual particles. They are properties of charges and they have no independent meaning.

I would answer no. It is a static filed having no relation to propagating particles - photons. It is similar to static Coulomb field. It is the photon propagator which is called a virtual photon actually. The main part of this propagator is the usual Coulomb interaction between charges, so it is not a photon at all. There is also some retardation effect involved in this propagator and this makes it look like a "radiated wave". In the first Born approximation, however, one does not calculate effects of really radiated photons although they accompany any scattering experiment. As soon as this part of retardation effect is not included, the meaning of the propagator retardation is vague and cannot be "absolutized". It is better to keep in mind the main, Coulomb part of charge interaction. It is just a potential energy of charge interaction. In QM there are also quantum mechanical effects connected with non-local (smeared) nature of "particles" as de Broglie waves. This makes the selective (propagator) retardation even more vague. Similarly for the electron magnetic field.

Never joke like this. If the person gets killed, it will be your responsibility.

No. It works only in dry conditions.

Because it's a push.

Right on the contrary: Me/Mp = 1/1836. It couples the proton and the relative electron-proton motions in Hydrogen.

Yes, I can but I will not. It's you duty.

Think of it as of very distant electron's not being able to influence us immediately. The event is out of light cone if cannot affect us immediately.

What is also important that it is additive in particles or other "species" involved in interaction. So its conservation means a clear thing: what is taken from one particle is given to another.