The Goldilocks Enigma: Why Is the Universe Just Right for Life?

by Paul C.W. Davies

Figure 27: What if there is just one universe? Like Figure 26, this diagram also depicts all that can in principle exist. Some physicists hope that there is only one possible universe consistent with a final, mathematically unified supertheory (for example, M theory) and that what we observe is it. (It would have to be!) If they are right, then what gets observed is all there is. (We may not be able observe it all at any one time, but what we don’t observe right now would be the same sort of thing as what we do observe.) However, this mathematically unique theory of everything would still not explain why this universe is the one that exists, as opposed to all other logically possible universes that don’t “have fire breathed into them,” for example, universes described by other unified theories that do not fit the observational facts of our universe, depicted here by the dark region on the other side of boundary B.