Lex quotes JBS Haldane, "...the Universe is not only queerer than we suppose, but queerer than we can suppose." We can't suppose how queer it is, because we don't have the tools. Our perception is so limited. Birds see more colors than we do. Donald Hoffman shows that our understanding of reality is almost assuredly wrong. Given those perspectives, I would say that the number of alien civilizations in our galaxy and universe would be infinite.