Bob_for_short

orbital motion of two bodies is possible and happens indeed but it is a "bound state". There may be unbound (non restricted, more energetic) motion like flying apart.

Look, the virtual photon is mostly the Coulomb potential of an electron (a propagator that reduces to 1/r in the non-relativistic case). It is well observable but it is not a photon in any sense and it cannot be detached and thrown away. That is why I say that there is no virtual particles in the classical vacuum (i.e., in an empty space).

It has always been clear. The energy is measurable. The energy is exchangeable. The energy is a certain property of a system. There are many forms of energy. Each is well defined. Why to fool ourselves?

Somebody pushed them apart in the past and they fly apart since then.

We expand the exact solution in series in powers of a small parameter. We consider the anharmonic term as small. So the zeroth-order approximation satisfies the pure harmonic equation. We find it. Then we try to obtain an equation for the first correction. For that we put them together in the equation. We obtain an equation which contains now the known zeroth-order approximation in the anharmonic term. The zeroth-order solution plus the first-order correction is a more accurate solution (smaller error).

I made a double-slit experiment with only one photon. I obtained one point on my screen. I wanted to get the other points from the other worlds in order to superimpose them and obtain an interference picture. I looked at the screen, behind it, and also in all perpendicular and non perpendicular directions. I have not found any other screens, leaving alone other worlds, and thus no additional points. Then I repeated my experiment with projecting many-many photons at the same time and immediately obtained a descent interference picture (ensemble of points). I managed to carry out the experiment in this sole world without problem. So I decided that MWI guys were cheating me for fun.

Correct. Somebody fooled me with other worlds and someone fooled you with gold mines (run out of gold obviously).

I have searched many times there where they should be and found nothing.

Let us suppose that MWI is right. Than we should have the other worlds at hands together with our world in order to make sure that other possibilities are well realized in them. But we don't have them. Then why to involve or invent something in our science that we do not have for sure? Conclusion: MWI is wrong as it appeals to non existing other worlds. The same is valid for lost and hidden variables.

Yes, whatever the words mean, as soon as you use words, it is already an interpretation, and nobody can blame you for that.

Prove what? That there are no other worlds? That people, insted of accepting the complexity of this world, invent deterministic pictures furnished with hidden parameters or other interpretations? The fact that there are many of them and they are different proves already what you ask.

I did not tell that the MWI is the only wrong one. There are many of them. Still, we all in our daily practice think of this world solely. This is sufficient, fortunately.

As soon as we (you) replace the word "vacuum" with the right term "the ground state of the system", no paradoxes will arise. You have a system in the minimal possible energetic state. Nothing to harness. As simple as that.

I am somebody who has his own opinion based on his own experience (practice). Referring to other worlds without any possibility to verify where they are and what happens there is not science. It's telling stories. Everybody in life cares about this world. This is the human practice. And science is a systematisation of facts of this practice.

The Swansont first paragraph is the most exact answer. Referring to parallel universes is a weakness of some physicists. Give sufficient number of trials and even a low-probable event will occur. As simple as that.

I need a salary from nothing. It's much less than the Universe.

Let us consider a long-wave radiation with a short antenna. Is the EM wave separated from antenna? You see, any radiation needs a source somewhere. It does not appear in a fully empty space. Let us consider a thermoelectric emission of electrons from radio-lamp cathods. It is a transfer from the ground to highly excited states of cathod atoms. Any radiation - photons and pairs is a transition from the ground state (=quantum vacuum) to an excited state of the original, real system rather than of empty space (classical vacuum). Thus the "virtual particles" belong to real particles/systems and not to the empty space. It is a real particle feature. Without it there is no virtual particles. The pairs are created from the quantum vacuum, not from empty space (=classical vacuum).

Yes, I did. I attract your attention to the fact that it is the blackhole that radiates, as any material system out of thermal equilibrium with its environment.

You had a good idea. It is not your problem that it failed but of those who are responsible for speaking of "vacuum energy" in empty space.

I am only against a vulgarization of science. Those questions about harnessing the "vacuum energy" are provoked by this vulgarization. And I give an explanation what is meant by the virtual particles.

These are experimental evidence of real particle interactions. Think of the Coulomb potential. In QED it is a "photon propagator" called also a "virtual photon". But in fact, it is mainly a usual Coulomb potential (solution of the field equation with a charge as a source). Some minor quantum corrections to it do not invalidate the physics - it is an inter-particle interaction of real particles. It is quite incorrect to think that a usual empty space (classical vacuum) is filled with virtual particles.

There is no imaginary or virtual particles, as a matter of fact. It's an awkward way of physicists to name interactions (forces like Coulomb one) in calculations. Accelerators can provide high momentum particles which is an efficient way to create a recoil, but! But the particles are charged and to keep the space-ship neutral you have to eject the equal numbers of positive and negative particles. It is done indeed - in the so called ion-jet engines which in fact eject neutral plasma beams.

In an empty space (a classical vacuum) there is nothing. A quantum vacuum is a synonym to the ground state of some compound system. If your spaceship is cold (T=0) it is in its ground state. Thus there is nothing to harness. If your spaceship is hot (T>0) it can emit an electromagnetic radiation. It provides a kind of radiative recoil. It is rather inefficient though. Better "radiate" particles, as in jet engines. This is how the excess of energy (the energy above the ground state in the combustion chamber) is employed.

In fact, what is usually said about the Casimir effect is not virtual pairs (electron-positron pairs) but virtual photons or the "zero-point energy" of the virtual photons. Casimir first predicted this effect and later on they measured that force. The strict understanding of this effect is a long-distance interaction of neutralized charges. It is their potential energy that is calculated and its gradient determines the force. You know, it QM the charges are "smeared" quantum mechanically, they are not point-like, so their interaction is somewhat different from pure point-like particle interaction. In addition, there is the quantized electromagnetic field "hooked" at each charge that gives an additional smearing. For neutralized distant charges this additional force dominates.

It is quite similar to attraction (or interaction) of distant neutral atoms, a la van der Waals force. Gravity effect is too weak.