What I'd like to know:
The mass-energy from S.R and used in the energy tensor part of the field equation gives the source of gravity. Therefore does the vacuum energy source gravity too?
Imagine a distant part of space say between our galaxy and Andromeda where the gravity is weak and theres not much matter. Suppose by chance a cubic metre was free of any matter or EM radiation by chance. Would that cubic metre be filled with the zero vacuum enegy?
Given that the universe is expanding does the vacuum energy under the conditions described in (2) remain constant? and does the cubic metre of vacuum energy expand with the universe?