## Wednesday, May 27, 2015

### balance dark matter and dark energy

can you compute the scale factor $a$ at which a $\Lambda$CDM-cosmology has a total deceleration of zero? is there an equivalent more general result for dark energy components with a constant dark energy equation of state parameter $w$?

#### 1 comment:

1. No deceleration means q=0, or lambda=Omega/2. On the other hand, lambda/Omega is proportional to the cube of the scale factor. (H changes with time, but cancels out; the cube comes from the fact that matter thins out with the volume of the universe, but the cosmological constant doesn't.) This is all the information one needs to calculate the scale factor at which q=0, depending on the values of lambda and Omega today.