This is something that is an emotional barrier to mainstream science. I've continued to watch the PBS series with Brian Greene and there are so many subtle barriers you pick up on with these scientist. Like the idea that there could be other universes beyond our own. One scientist equated the idea of other universes with the idea of angels. We all know how scientists feel about religious concepts, so that's just a loaded statement to make. Yet it is difinitive in their minds simply because it is the human limitation of the boundary of where we are able to 'detect'. It's a complete ego based rational that they use.