Cosmology phenomena

The cosmos is the universe, as we observe it from the earth (and therefore excluding the earth).

Any account of the cosmos would need to address the following phenomena:

1. We observe background radiation, consistent with the Big Bang having taken place.
2. Our observations of cosmological redshift are consistent with the proposition that the universe is expanding.
3. We observe that the universe looks the same in all directions.
4. We observe a lumpiness of space which is consistent with the observed formation of galaxies.
5. We observe that the rotational speeds with which stars in spiral arms of galaxies revolve around the galactic centre of mass does not continue to attenuate after a given distance from the centre, but remains almost constant.
6. We observe that some distant massive objects focus the light of objects behind them, to a degree that is far in excess of the gravitational lensing which might be expected on the basis of their visible mass.