Red-shift as Evidence for the Big Bang
The universe is really old but it did have a beginning, when time and space started. Evidence for this has been found in star light, which is red-shifted because the space between galaxies is expanding.
Dark Matter and Dark Energy
Recent observations indicate that the rate of expansion of the universe is increasing, but we don't know why. There is a lot that we are still discovering including dark energy and dark matter.
You may also be interested in...