The cone is a good way to explain it to add the flow of time, and the cone shape comes from the expansion of the universe. The tip is the big bang and the wide

The cone is a good way to explain it to add the flow of time, and the cone shape comes from the expansion of the universe. The tip is the big bang and the wide end of the cone today. By taking a telescope and looking back in time we would be looking at a smaller universe heading towards the big bang in the cone, and hence the redshifted nature of what we see - since the universe is smaller. If you were to take a slice of the top of the cone, that is your spherical view of the universe today - in 3d. The cone is 4d.