[KayEyeDoubleDee]

Dark energy is just like gravity, except it pushes rather than pulls.

Equating "energy" to "gravity" doesn't make much sense too me. If it is truly a repulsive force (in which case they should have called it something like "dark gravity" or URF, Unknown Repulsive Force) then what does it act on? What does it push? Normal matter? Dark Matter? The "fabric" of space-time? Or is it really just another Einsteinian Comsmological Constant, plucked out of thin air to explain the unexplained.

[RightWhale]

Strangely, I have never had a problem with the idea of negative gravity. Assuming the universe is half matter and half anti-matter, the net force [gravity] ought to be repulsive. Inside a given galaxy would be predominantly matter or anti-matter, not both, so internally gravity would be of attraction. Between galaxies there would be both gravity and anti-gravity fields and the net would be repulsive, as we see, with knots and assemblages of either matter or anti-matter galaxies, not both together. It's probably a naive view, but what do whales know.