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waterfall
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In the thread https://www.physicsforums.com/showthread.php?t=343049
Science Advisor Born2bwire mentioned: "Since the vacuum state has infinite energy, it has infinite photons. Everytime we add energy into the electromagnetic fields, we just pull a photon out of the vacuum state." How many believe this and is there a refutation to this idea... because it seems that if it is true, then beneath the quantum vacuum lies a source of infinite energy.. literally".
Born2bwire wrote:
Science Advisor Born2bwire mentioned: "Since the vacuum state has infinite energy, it has infinite photons. Everytime we add energy into the electromagnetic fields, we just pull a photon out of the vacuum state." How many believe this and is there a refutation to this idea... because it seems that if it is true, then beneath the quantum vacuum lies a source of infinite energy.. literally".
Born2bwire wrote:
A quantum vacuum is simply a fancy name for the ground state. That is, it is the lowest energy state of the system. The interesting thing about the electric and magnetic fields in quantum electrodynamics is that their ground state is represented by zero photons. However, their ground state is not zero energy. In fact, in a completely empty space, the quantum vacuum can have an infinite number of frequencies of fluctuating fields occurring, a continuous spectrum. Each frequency represents a mode, a possible excitation of the fields in the system, and each mode has a certain discrete energy density. So the quantum vacuum has infinite energy if we do not restrict the possible frequencies of electric and magnetic fields. One way to think of this is that in quantum electrodynamics, we think of the photons as being the energy packets (quanta) that occur when we excite the electromagnetic waves. Each energy level of the electric and magnetic fields represents an additional photon being excited. These photons "come" from the vacuum state. Since the vacuum state has infinite energy, it has infinite photons. Everytime we add energy into the electromagnetic fields, we just pull a photon out of the vacuum state. It's an interesting idea, I recall I think it was Dirac who mentioned it.
Where this energy comes from we do not say. All we know is that in quantum mechanics, we often get systems where the energy cannot go to zero. Since we have an energy "bath" that we can draw upon, it forces fluctuations in the system (this is an idea from the fluctuation-dissipation that I mentioned earlier). For example, let's say I have a system that draws energy from a heat bath that surrounds it. It is constantly drawing energy from the bath but it cannot put energy back in. We find out that this stipulates that the system must have fluctuations. In the same way, we must have fluctuations in the vacuum state as well. But since these fluctuations are about a mean of zero, they are not measurable in the macroscopic world. So we never see truly see them. Sure we can get non-zero measurements should we attempt them but statistically we will only get a zero measurement in the long run.
So again, we can't say where the energy comes from, it's a definition of the quantum system. The fluctuations of the field can be explained in a few ways. We an show taht it must occur via mathematical rigor of quantum mechanics. The closest "physical" reason I have found is that the vacuum energy is an energy bath that couples with the electric and magnetic fields. Because of this, the fields must have fluctuations as shown by statistical mechanics. Photons are nothing more than the energy quanta of the electric and magnetic fields. We can think of them as being drawn out of the energy of the vacuum state. When they are created they come from the vacuum and when annihilated they return. Of course this may not be a truly physical picture. Anytime we add energy to the fields we create photons. Since they are nothing more than massless particles of energy/momentum, it is hard to say what they are created of. So if I dump energy into the fields using an antenna, then am I drawing the photons up from the vacuum or just creating them from the energy injection from my antenna.
As for virtual particles, they are not real. It is hard to say what they are but I have not heard of them as being any physically real object. They can be useful calculation tools though in Feynman diagrams. In the quantum vacuum, we can represent the vacuum fluctuations as virtual photons. The idea is that we momentarily create the photon let it interact and then destroy it. In the end, because we created and destroyed the particle we add no energy to the fields, but by allowing the particle to interact it is the same as allowing the field fluctuations to have interacted. For example, in the Casimir force, we can calculate it from the force induced by the fluctuation fields or we could calculate it as the "radiation" pressure force of the equivalent virtual photons. The results are identical.