“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.