“Another very good test some readers may want to look up… is the Casimir effect, where forces between metal plates in empty space are modified by the presence of virtual particles.” -Gordon Kane
If you ask what the zero-point energy of space itself is, you can sum up all of the quantum fluctuations you can that arise in quantum field theory, and arrive at an absurd answer: 120 orders of magnitude greater than the observed. Yet if you assume that there’s an incredible cancellation and you get exactly zero, that removes the one thing our Universe needs to explain its expansion: dark energy.
Yet the Universe has matter, radiation, the Hubble horizon and other forms of artificial boundaries in it, and we know that boundaries (like metal plates in electromagnetism) can cut off some of the allowed modes of quantum fluctuations, and lead to a real force: the Casimir effect. Could this same effect — which exists for all the forces, not just electromagnetism — be responsible for dark energy?