Physical Interpretation
A nonzero cosmological constant term can be interpreted in terms of a nonzero vacuum energy. There are two cases:
- : positive vacuum energy density and negative vacuum pressure (isotropic suction), as in de Sitter space,
- : negative vacuum energy density and positive vacuum pressure, as in anti-de Sitter space.
The idea of the vacuum having an energy density might seem outrageous, but this does make sense in quantum field theory. Indeed, nonzero vacuum energies can even be experimentally verified in the Casimir effect.
Read more about this topic: Lambdavacuum Solution
Famous quotes containing the word physical:
“Be sure that it is not you that is mortal, but only your body. For that man whom your outward form reveals is not yourself; the spirit is the true self, not that physical figure which can be pointed out by your finger.”
—Marcus Tullius Cicero (106–43 B.C.)