Human brains did not evolve with the capacity to easily understand distances in the visible universe. I first began to grasp the size of the universe after pondering the following line of thought:
1. The Voyager spacecraft is outside our solar system, travelling at 11 miles/sec.
2. It will reach the nearest star in the year 73,000 AD.
3. On top of that, there are 200 billion stars in our Galaxy.
4. Then beyond that, there are 200 billion galaxies in the visible universe, with the nearest one, Andromeda, being 2.5 Million light years away.
Which specific lines of thought help you understand the size of the visible universe?