I Does dark-energy require a source of energy?

[Herbascious J]

TL;DR Summary

Does dark-energy require a source of energy if explained by general relativity and the Lamda-CDM model?

In the Lamda-CDM model of cosmology, dark-energy is explained by a Lamda like curvature of space-time. In this description, space-time is curved in such a way as to cause a gentle outward repulsive force on the large scale, expanding all of the universe over time. This is one cause of the Hubble flow.

In general relativity, when dealing with gravity, if a body falls toward a massive object, this is thought of as a release of potential energy into kinetic energy. The curvature of the gravitational field already exists and looks like a force. My question is if dark-energy is a curvature of space-time, wouldn’t this be more like a force, not a kind of energy? So the universe on the largest scales would be expanding not because energy is flowing into it to drive it apart against the force of gravity, but instead the expansion is the result of potential energy being released under the influence of a force.

So, does dark-energy require an energy source, or is it just the result of the curvature of space-time? Is that what is meant by "energy" or is there some other explanation as to why we call it dark-"energy"?

Source:
https://en.wikipedia.org/wiki/Lambda-CDM_model

 

[Ibix]

Dark energy is supposed to be a form of energy that, like any other, causes spacetime curvature. It is not itself spacetime curvature.

So no, it does not require an energy source any more than mass requires an energy source.

It's very tempting to equate dark energy with the quantum field theory idea of "energy of the vacuum", the energy that's just there in empty space. Back of the envelope estimates for this quantity (we don't know how to do a proper calculation) are off by 120 orders of magnitude compared to observation, though, so clearly there's something we aren't getting right.

 

[vanhees71]

I think, this still is one of the best explanations of the "cosmological constant problem".

https://repositories.lib.utexas.edu/bitstream/2152/61094/1/Weinberg_1989.pdf

Weinberg has written another paper that there's also one more other problem ;-):

https://arxiv.org/abs/astro-ph/0005265