I Vacuum energy versus expansion of the Universe

[Italian_Mike]

If vacuum energy has a non-zero value, is the vacuum energy density (vacuum energy over a given volume of void space) being reduced over time due to the expansion of the Universe?

If so, is there any consequence on the particle-antiparticle creation/annihiliation process? Will there ever be a time in the ditstant future where the vacuum energy density is so low that some of these processes are not possible anymore?

Thanks for your replies!

 

[Demystifier]

If vacuum energy has a non-zero value, is the vacuum energy density (vacuum energy over a given volume of void space) being reduced over time due to the expansion of the Universe?

Observationally, all observations are consistent with constant vacuum energy density. Mathematically, constant vacuum energy density is consistent with covariant conservation of energy-momentum tensor of matter. Conceptually, you can think of it as increase of total (positive) energy of matter at the expense of decrease of total (negative) energy of gravitational field.