Quote:
PeteMo said...
Also, how do we explain galaxies like the Andromeda heading towards us when other galaxies are heading away at an even greater rate of knots.
|
This is because within our local group and local supercluster, galaxies and clusters are gravitationally bound. Beyond that, distances are to great and cosmic expansion dominates over gravity. There is slight variation in galaxy redshifts, the source of which has been dubbed the Great Attractor, but it is not enough to overcome the Hubble flow.
On the subject of dark energy, I'll have to defer to the professional community. We seem to have plenty of observational evidence that there is a repulsive energy at play, but no real theory to explain what it actually is. I guess for me the neatest explanation is the cosmological constant, as it based on our two existing theories, General Relativity and Quantum Mechanics.
Andrew.