Question: They say the Universe is infinite. How big is infinite?

Mike Lee answered on 14 Mar 2014:

We don’t really know if the universe is infinite. It may not be, but we don’t know for sure — yet. Due to the way the universe came into existence and the way it expands over time, from our point of view in the galaxy we can only see so far.

How big is infinite? Picture a road that stretches on forever and ever, or an ocean that has no shores. Count up to a certain number, and then add one. If something is infinite, like the universe may be, you can always add one more and there would still be some room left.

If you had a hotel with an infinite number of rooms, all occupied, you could ask each of your guests to move over to the nearest odd-numbered room and you would be left with an infinite number of even-numbered rooms. There is an infinite amount of odd numbers and even numbers, but odd and even numbers together form a set that is even more infinite than the odd and even sets taken separately. This means that some infinities are bigger than others!