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One of the consequences of Heisenberg’s Uncertainty Principle — that you can’t know a quantum state’s energy exactly for a finite duration of time — means that when you’re talking about very short time intervals, there are large uncertainties in the energy of a system. Over short enough timescales, the energies are large enough that particle-antiparticle pairs wink in-and-out of existence all the time!
Take two identical, uncharged, parallel metal plates, and put them close to one another. The vacuum fluctuations in between the plates cause there to be a pressure pushing the plates together. This isn’t the gravitational force or an electromagnetic force, but a force due to empty space itself.
Now, that’s what we know we can get, even from nothing. But there are many things we can’t do, either practically or theoretically: violate charge or energy conservation, decrease the total entropy of the Universe, or figure out where our initially inflating Universe came from. (Yet!) But we definitely can get something for nothing; quantum field theory not only allows it, it demands it.
The only true vacuum that has ever been found is the space between two human ears.
Space boils with energy -- it can be bent, twisted, curved -- it is quite different from "Nothing."
The Cassimir Effect is hard, experimental proof of this. The force between the two plates arises because the longer wave lengths of the virtual particles which fill space cannot "fit" between the two plates -- the distance between the two plates is too short for them. So there are more virtual energies outside the plates than between them, which creates the pressure which drives them together -- and the experimental results agree closely with the theoretical predictions.
Moreover, the elementary particles have magnetic moment -- due to their quantum mechanical spin. It should be
2 exactly -- but external effects due to interactions with the virtual particles and energies of the vacuum change this figure, for the electron's anomalous magnetic moment, to : 2.00231930436153(53).
At last reading, this is the most accurately measured figure in the entire history of physics, and is the most accurate fit between theoretical calculation and experimental measurement that has ever been achieved.
The quantum flux of virtual particles is clear and proven, and the vacuum is
NOT "Nothing" !!
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