# The nature of dark energy

## Main Question or Discussion Point

Moderator's note: Spun off from another thread due to topic change.

Isn't Dark Energy a continuous creation theory?

Last edited by a moderator:

PeterDonis
Mentor
2019 Award
Isn't Dark Energy a continuous creation theory?
No.

As the universe expands, won't Dark Energy get diluted and grow weaker? Will it grow weaker at greater distance away?

phinds
Gold Member
2019 Award
As the universe expands, won't Dark Energy get diluted ...
No, dark energy has a constant density under expansion.

PeterDonis
Mentor
2019 Award
As the universe expands, won't Dark Energy get diluted and grow weaker?
No.

Will it grow weaker at greater distance away?
This question doesn't make sense; a density has nothing to do with a distance. The density of dark energy is constant.

Constant density with increasing volume means adding material. What does density mean?

phinds
Gold Member
2019 Award
Constant density with increasing volume means adding material. What does density mean?
There is NO material to "add", it's just everything (non-bound systems) moving apart from every thing else in space-time but with the amount of dark energy (whatever it IS) unchanged per unit volume.

This can be difficult to get your head around at first but nature doesn't care about our faulty "intuition / common sense".

PeterDonis
Mentor
2019 Award
Constant density with increasing volume means adding material.
Dark energy is not "material" in the sense you are using the term here.

Is that like the metric expansion of spacetime? Is it true that one can't say that spacetime is expanding, being created, or stretching?

timmdeeg
Gold Member
Constant density with increasing volume means adding material. What does density mean?
In a sense yes, but it isn't a material as already stated, it is vacuum energy. As John A. Peacock says in "Cosmological Physics" "the vacuum acts as a reservoir of unlimited energy". So increasing volume means an increasing amount of vacuum energy whereby its density (energy per unit volume) remains constant.

PeterDonis
Mentor
2019 Award
Is that like the metric expansion of spacetime?
Is what like the metric expansion of spacetime?

Is it true that one can't say that spacetime is expanding, being created, or stretching?
Yes. Spacetime is a 4-dimensional geometry. It doesn't change. It just is.

Is Dark Energy density constant in the Block Universe?

PeterDonis
Mentor
2019 Award
Is Dark Energy density constant in the Block Universe?
What do you mean by the Block Universe?

The last question is retracted as unconventional. No, it's not worth repeating.

PeterDonis
Mentor
2019 Award
The last question is retracted as unconventional.