We are taught that the universe is infinite, and yet also taught that the universe is expanding. How can something that is infinite also expand?
I can only hazard that we are living in a "multi-Universe". Any thoughts?
Remember that not only is matter contained within the universe, but also space between that matter. It would be possible, in the event of a huge cosmic explosion, such as the "big bang", for the matter in the universe to expand outward throughout the space. So, in that sense of the word, it is possible to have an expansion. Now let us examine the word "infinite". Imagine a room with no walls, with no ceiling, with no floor, that just went on, and on, and on. This is the definition of infinity, the one that has troubled man from the beginning, since man is used to dealing with finite entities. So in this unlimited amount of space, you have matter accelerating outward, away from each other, expanding, increasing the size of the universe. I do not think it would be unreasonable to examine the suggestion of "multiple universes" as it would be a logical next step in increasing the size scale. At one point, before telescopes, Ptolemy taught the Earth was the center of the universe, and the sun and the other known planets and stars all revolved around the Earth. As our technology has improved, so has the size of the playing field. A multiple universe concept would be just another adjustment to the concept that has been developing now for thousands of years.