If the universe is as big as they say it is or as some say ever expanding, we couldn't possibly be the only intelligent species. There are likely much much more advnaced and much more primitive as well. IMHO I don't think we have even scratched the surface of science and whats around us or what its made of. Did you see they recently discovered "dark matter." They supposedly can't see it but they know it exist becuz of its effects on gravity, etc.