Posted on Mar 21, 2012

What Copernicus, Galileo and Darwin did to disturb our self-centered view of the universe was nothing compared to Hugh Everett’s theory of quantum reality.


Modern existence is a constant affirmation of faith in quantum theory—or at least, faith in the theory’s ability to predict the behavior of light and matter. The semiconductors in computer chips, the diode lasers in DVD players, even the ticks and tocks of atomic clocks are all based on this 90-year old branch of science.

Quantum theory also gives hints about the basic fabric of reality, but these hints conflict so much with our intuitive view of things that we ignore them in everyday life. If we truly took these hints to heart, we might feel as Neo did when he took the red pill and woke up to the harsh reality of the Matrix. Like the Matrix, the current quantum model of the universe implies that our intuitive view of existence is illusory, our hunger for meaning a cosmic joke.

A basic idea of quantum theory is that the properties of particles naturally exist in a haze of uncertainty. One cannot predict the precise location of an electron, for instance; one can predict only the set of its possible locations and the probabilities of experimentally finding it at these locations. In essence, it seems that the electron exists in a ghostly multiplicity of states until one of those states interacts robustly with its surroundings, for example by the measurement process.

The “Copenhagen Interpretation” of quantum theory, which dominated from the 1930s until recently, held that the observed collapse of this multiplicity of possible states to one state – to the sharp reality that we normally perceive – means the simple disappearance of the other possible states.

However, it seems that most physicists now favor the “Everett Interpretation,” developed by a Princeton graduate student, Hugh Everett III, in the 1950s. Also known as the Many Worlds Interpretation (MWI), Everett’s concept implies that the other possible states in such cases don’t really go away. They continue to exist in other, inaccessible universes populated by other you’s and me’s.

In this view, the you that exists at the moment of your birth splits or differentiates into a near-infinitude of you’s with every possible life history – consistent with the physical laws that pertain in your area of reality. The history of Earth and its species also move along every possible trajectory. Across the cosmos – across the “multiverse”—everything that can happen does happen.

Professional theorists and popularizers have been writing about MWI since the 1980s. Perhaps believing that downbeat themes sell fewer books, these writers have tended to soft-pedal the implications, portraying this profound shift in thinking as merely part of the grand adventure of science: Thus, Copernicus dethroned us humans from the center of the universe; and Darwin dethroned us from our privileged space in the animal kingdom; and both times we coped; and so we shall cope again with this new and stronger existential relativism.

But the relativism of MWI is not merely stronger; it is, so to speak, absolute – and it absolutely mocks our intuitive sense of agency, responsibility and meaning. How can we condemn or praise an action that someone has taken, when we know that that action, from an MWI view, had to be taken, in order to fill out the vast space of possibility? How can we celebrate a hero in our world, knowing that he or she must be a villain in another? How can we find meaning in the minutiae of our history, knowing that that history is but one random branch in a vast cosmic tree?

It is some consolation that MWI is not a sure thing. But there is currently no feasible way to disprove it, and so we must live under its shadow indefinitely. Perhaps we shall just continue to take the “blue pill” and ignore its implications. As Simon Saunders, an Oxford University philosopher and MWI theorist, told a reporter several years ago, “I’ll just accept Everett and then think about something else, to save my sanity.”

But MWI is also a stark reminder of something that Nietzsche and other philosophers warned about long ago: Science is not an unshakeable institution. It is a cultural choice, requiring faith in the value of its truths. When those truths fail to “set us free,” and instead deliver existential poison, science’s own existence may become precarious.


For more on this theme, see my book, Everything and Nothing: an introduction to quantum probability.