The discussion centers around the nature of the cosmological constant and whether it should be considered a true constant or if it could exhibit dynamics influenced by spacetime. Participants explore theoretical implications and the simplicity of models in cosmology.
Participants express differing views on whether the cosmological constant should be treated as a true constant or if it could have dynamics. There is no consensus on this issue, as some support the constant model while others propose the possibility of variability.
Participants acknowledge the limitations of current models and the dependence on observational data, which may not support the dynamic models proposed. The discussion reflects the complexity and uncertainty surrounding the cosmological constant and its implications in cosmology.
Because a constant is the simplest model, and we have no evidence that it's not constant, so we use the simplest model that's consistent with the evidence.mad mathematician said:
I wonder how difficult it would be to to write down a model where it changes with time.PeterDonis said:
We usually call it "dark energy" when it's not assumed to be perfectly constant.mad mathematician said:
It's straightforward to write down the model; indeed doing that is an exercise in some advanced GR textbooks. The usual way is to use a scalar field.mad mathematician said: