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Apr
21
awarded  Revival
Apr
21
comment Vacuum is not really empty
The paper you quote makes on p.2 under the heading ''Vacuum and vacuum fluctuation'' a lot of unsubstantiated claims taken from the popular literature. The derivation of the Casimir effect given on p.3-5 makes no use at all of any of these wrongly claimed properties. The observed Casimir effect cannot be taken as proof of properties not used in its derivation!
Apr
21
comment Vacuum is not really empty
In the Casimir effect, particles do not pop into existence. See, e.g., physicsforums.com/posts/5448495, the references there, and the subsequent discussion there. See also physicsforums.com/posts/5449166 and the subsequent discussion.
Apr
21
comment Vacuum is not really empty
@AnubhavGoel: Nothing peculiar there: From the same gravitational field you can acquire more kinetic energy if you let a heavy ball fall than if you let a tiny ball fall. The point is that to turn this into a continuous source of energy you need to find a place such as a waterfall where there is a continuous supply of high potential objects to fall down. The same problem is in your situation, with the Coulomb potential in case of the gravitational potential.
Apr
21
comment Vacuum is not really empty
@AnubhavGoel: The maximum energy one can extract by free fall is the difference between the potential energy at the top and at the bottom. But you need to be somewhat clever to convert the kinitic energy at the bottom to useful energy. Water power is of this kind. - On the other hand, no energy can be extracted from a vacuum not containing fields.
Apr
20
comment How is the ground state chosen in a spontaneous symmetry breaking process?
A tachyonic state is impossible in relativistic QFT at T=0 since the Kallen-Lehman formulas require m^2>0.
Apr
20
comment How is the ground state chosen in a spontaneous symmetry breaking process?
Because at sufficiently low temperature the unbroken symmetry state doesn't exist because of the presence of unphysical tachyon states.
Apr
20
comment How is the ground state chosen in a spontaneous symmetry breaking process?
There is a difference between out of equilibrium states (of which there are many) and unbroken symmetry states (which do not exist in the zero temperature case).. Note also that baryogenesis is at high temperature, so the last paragraph of my answer applies there.
Apr
20
revised What really goes on in a vacuum?
improved argument and references
Apr
20
comment Are vacuum fluctuations really happening all the time?
No truth at all; see physics.stackexchange.com/a/250814/7924
Apr
20
comment Vacuum is not really empty
-1: This is the popular science view. It has no sound basis in quantum theory.
Apr
20
answered Vacuum is not really empty
Apr
20
answered How is the ground state chosen in a spontaneous symmetry breaking process?
Apr
19
answered Is Huygens's Wave Theory still correct?
Apr
18
comment Do virtual particles actually physically exist?
For a thorough discussion of misconceptions about virtual particles (including precise definitions and references) see my article physicsforums.com/insights/misconceptions-virtual-particles
Apr
18
comment Virtual photons, what makes them virtual?
For a thorough discussion of misconceptions about virtual particles (including precise definitions and references) see my article physicsforums.com/insights/misconceptions-virtual-particles
Apr
14
comment The virtual particles are only a fictive tool in equations? DO they exist or DON'T? And if they exist, why do we call them VIRTUAL?
@annav: Yes, it is a book-keeping device, not something real.
Apr
13
revised The virtual particles are only a fictive tool in equations? DO they exist or DON'T? And if they exist, why do we call them VIRTUAL?
added 135 characters in body
Apr
13
revised The virtual particles are only a fictive tool in equations? DO they exist or DON'T? And if they exist, why do we call them VIRTUAL?
added excerpt
Apr
13
comment The virtual particles are only a fictive tool in equations? DO they exist or DON'T? And if they exist, why do we call them VIRTUAL?
I wrote in my essay there only what is essential. One really needs an extended discussion to clarify all the things that typically come up in the discussions - short answers cannot do justice to the problem. But I'll add a little bit from the second article.