Is the cosmological constant equivalent to vacuum energy?

[Naty1]

Wikipedia says:

Two proposed forms for dark energy are the cosmological constant, a constant energy density filling space homogeneously,[3] and scalar fields such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant is physically equivalent to vacuum energy. Scalar fields which do change in space can be difficult to distinguish from a cosmological constant because the change may be extremely slow.

second paragraph here: http://en.wikipedia.org/wiki/Dark_energy

Vaccum energy (density) can vary over time and space?

Is that accurate? I've read the cosmological constant can vary, but not vacuum energy.

 

[Nabeshin]

Wikipedia says:



second paragraph here: http://en.wikipedia.org/wiki/Dark_energy

Vaccum energy (density) can vary over time and space?

Is that accurate? I've read the cosmological constant can vary, but not vacuum energy.

I think you misread the quote. They say there are two kinds of dark energy: A true cosmological constant (in the sense of \Lambda in Einstein's Equations), and then scalar fields. If the scalar fields DO NOT vary spatially, then we can lump them in with Einstein's cosmological constant. It is these scalar fields which are physically equivalent to the vacuum energy.

 

[Naty1]

So the boldface quote is wrong:

The cosmological constant is physically equivalent to vacuum energy.

Thanks.

 

[Demystifier]

It's wrong, but it doesn't take much to rewrite it correctly:
The cosmological constant is physically equivalent to constant vacuum energy.