# Dark energy time dilation

I have read here that dark energy is somewhat like negative mass. Here Wikipedia states:

... that the cosmological constant required that 'empty space takes the role of gravitating negative masses which are distributed all over the interstellar space'.

If you take the equation for spherically symmetric time dilation $$t_0 = t_f \sqrt{1 - \frac{2GM}{rc^2}}$$ and substitute a negative mass, you get a $$t_0 >1$$ time dilation factor, suggesting that time moves faster under gravitating negative masses.

Is this consistent with observations (say, are photons traveling through the intergalactic medium 'time-accelerated' [I have never heard of such a thing, so this must be wrong]) or is dark energy not a gravitating negative mass, or am I looking at this all wrong?

• @BMF: For the sign of $\Lambda$ that we observe in our universe, dark energy acts like a perfect fluid with a positive mass-energy density and a negative pressure. Also, in the first question I linked, the answers seem to suggest that dark energy could be negative mass. No, they don't. And it's good that they don't, because that would be incorrect. I've also seen serious research into the idea arxiv.org/pdf/1712.07962 That paper is discussing a whole different, non-mainstream model. – user4552 Sep 26 '19 at 21:37