The latest question is, is our Universe the only one?

...it's actually a very old question, typically what the ancients meant by asking: is there more than one world? Because the geocentric World was bounded by a sphere of stars and seen as the complete Order of Things (a kosmos) that was deemed the totality of the Universe/World. Hence Democritus meant an infinity of what we would call Universes today when he spoke of an infinity of Worlds. Aristotle rejected this view and many typically followed Aristotle because they couldn't conceive of separate Orders of the World - what we'd call Laws of Physics. Some people still can't, while others posit a Multiverse/s. I think it's a matter of metaphysical taste since most scenarios are disconnected from experimental verification - though not all. A few multiverse theories have experimental consequences.

Atheists often invoke the multiverse to avoid god - I think positing one infinitely complex metaphysical entity in place of another is a shell-game.

Adam