I have trouble understanding how the Casimir effect, the vacuum, inflation, the cosmological constant and dark energy are related, if at all. My muddled understanding (which I'm hoping folk on this forum can clarify) is as follows: The Casimir effect is a weak attraction between closely spaced metal plates. It’s been experimentally measured. The attraction is attributed to a deficit of long-wavelength zero-point energy modes of the confined vacuum of the electromagnetic field between the plates, compared with its unconfined vacuum outside. The demonstrated existence of the Casimir effect proves that the vacuum of a field (i.e. Nothing at all) has energy. In cosmology it is postulated that in the early universe there was a Field whose Vacuum had energy, and that this Field, which was derived from a Potential, could exist in a metastable state called the false vacuum, whose energy density was of the order of 10^81 Kg/m^3. The decay of the false vacuum into a lower energy state (the "true" vacuum) is postulated to have driven a exponentially rapid expansion, called inflation. The cosmological constant, on the other hand, which might be assigned to vacuum field energy, now has an energy density of order 10^ (-31) Kg/ m^3, if it is indeed non-zero. And then there is the postulated but unidentified "dark" energy which helps to keep the universe flat, whose density is of a similar order of magnitude. It too might be vacuum energy. But the huge discrepancies between the orders of magnitudes of vacuum energy and these other energies render such identifications impossible. Now in the Standard Model it is agreed that, during the “ordinary” expansion of the universe, the density of mass/energy decreased from initially very high values to a present tiny average value. Is it not then possible, during inflation, that (some of?) the (enormous) energy contained in the false vacuum, trapped as it was in the inflating universe, was similarly diluted during the many e-fold expansions of inflation, until it now masquerades as a (tiny) dark vacuum energy cum cosmological constant?