Testable anthropic predictions for dark energy

In the context of models where the dark energy density ρ_D is a random variable, anthropic selection effects may explain both the “old” cosmological constant problem and the “time coincidence.” We argue that this type of solution to both cosmological constant problems entails a number of definite predictions, which can be checked against upcoming observations. In particular, the anthropic approach predicts that the dark energy equation of state is p_D=-ρ_D with a very high accuracy, and that the dark energy density is greater than the currently favored value Ω_D≈0.7. Another prediction, which may be testable with an improved understanding of galactic properties, is that the conditions for civilizations to emerge arise mostly in galaxies completing their formation at low redshift, z≈1. Finally, there is a prediction which is not likely to be tested observationally: our part of the universe is going to recollapse eventually, but it will take more than a trillion years of accelerated expansion before this happens.