Do Dark Energy and the Casimir effect indicate Exotic Matter could exist?

[okabe rintarou]

TL;DR

Dark energy causes repulsive gravity (negative pressure), and the Casimir effect shows localized negative energy density. Do these real-world phenomena indicate that the underlying physics for theoretical "exotic matter" actually exist?

I have a conceptual question about whether certain physical phenomena suggest that exotic matter is possible in our universe.

From my understanding, there are two phenomena that seem to behave inversely to normal matter:

Dark Energy: It is spread evenly throughout the universe (almost like a mist) and causes a repulsive gravitational effect due to its negative pressure.

The Casimir Effect: It demonstrates that it is possible to achieve a localized state of negative energy density (or negative mass density) between two close, uncharged plates.

Since theoretical "exotic matter" is usually described as needing negative energy density or repulsive gravity, do these two real-world phenomena indicate that the underlying conditions for exotic matter actually exist?

 

[Ibix]

I don't think the Casimir effect does, no. My limited understanding is that it can be rewritten as an effect of van der Waals forces, suggesting a rather more prosaic origin, although I'll defer to others on that.

Dark energy, maybe. It depends what it turns out to be. It is possible it isn't anything - that we've miscalculated something and dark energy is actually the gap between our calculations and the calculations we should have done. Or if dark energy is truly a cosmological constant then it might well be a property of spacetime, not a type of stuff in spacetime at all. Or, it may be a kind of exotic matter. So maybe, as I said.