Amir D. Aczel writes often about physics and cosmology. His book about the discovery of the Higgs boson, Present at the Creation: Discovering the Higgs Boson, is published in paperback by Broadway Books in November 2012.
If somebody told you that there are angels floating in space, observing our world and forming their impressions of our everyday reality, you would think that this person is nuts—a religious fanatic with an active imagination, and certainly not a scientist. Scientists, as we all know, are rational beings who believe only in what nature reveals to us through experimentation and observation, coupled with theory that is never divorced from the physical measurements they make. The link between the two remains tightly regulated through the strict rules of the scientific method.
So how do you explain the bizarre fact that, for about five years now, some of the world’s most prominent physicists have been describing a scenario—which they seem to truly believe may be real—in which, instead of the Biblical angels, space is permeated by disembodied brains?
These compact, conscious observers, called “Boltzmann brains,” cruise the vastness of intergalactic space, and beyond it, to the infinite “multiverse” that some scientists believe exists outside the reaches of the universe we observe through our telescopes and satellites. Their consciousness makes the Boltzmann brains recreate our reality. They imagine life such as the one you and I believe we are experiencing here on Earth, to the point that these brains in space may think that they are living on a planet like ours, that they may even be us. Some recent physics papers and commentaries have even explored the possible limits on the number of Boltzmann brains in the universe as compared with “real” brains, in an effort to estimate the probability that we are real rather than Boltzmann entities.