If our Galaxy truly contains many intelligent civilizations, some of which may be ahead of us by a billion years, how is it possible that we have not seen any sign of them yet? Nobody knows the answer to this so-called "Fermi Paradox," but one of the speculations is that there exists some bottleneck to the emergence of intelligent civilizations, and that this bottleneck could have either been in our past, or we will hit upon it in the future.
Beware what follows! I have no more right to be thinking, much less writing, these words than the last drunk picked up in Times Square last night. But, I am, possibly, different from that guy because I read the Science Times in the New York Times on June 9th. I doubt they supply the TIMES daily in jail?
Scientists have assigned the role of Mister Answer to science, the source of knowledge on every subject. This is peculiar because science does not accept a complete body of knowledge at any one time as final, therefore no answer can be final. This is how science progresses. Scientists, though, often forget that.
Greater comfort, I think, is to be found in the realization that infinity is as problematic for science as it is for religion. Much as an infinitely perfect God leads to logical clashes with reality, an infinite multiverse bedevils attempts to apply tools such as probabilities to our understanding of the world.
At an international conference in Mexico a few years ago, Richard Dawkins, having expounded at length on how sexual natural selection explains life on Earth without any need for a "creator," went on to say, "And I am sure that something like the principle of natural selection operates in the physical universe as well." Sounds totally silly? Well, there's more to it: a huge irony.
Let's look at the very vocal minority of theoreticians who, without a shred of experimental evidence to support their claims, are now telling us what, in their view, nature is truly made of. They do it mostly through recent books aimed at the average reader. I will survey the most widely read of these books.
It's a sensational breakthrough involving not only our cosmic origins, but also the nature of space: by producing the first-ever detection of Hawking radiation (the process by which inflation's rapid doubling generates these gravitational waves), the BICEP2 team has found the first experimental evidence for quantum gravity.
Given that the different members of the multiverse are not causally connected, the question that emerges is whether there is a way to verify whether such a multiverse truly exists. As it turns out, there are at least two possible paths that could (at least in principle) test the multiverse scenario.