Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
The Multiverse: The Quest for Certainty
The traditional (or “Copenhagen”) interpretation of Quantum Mechanics seems to be trapped in its unwavering faith in uncertainty. Others have looked for ways out of uncertainty.
One possibility is to deny that the wave function collapses at all. Instead of admitting a random choice of one of many possibilities for the future, one can subscribe to all of the possibilities at the same time. In other words, the probabilistic nature of Quantum Mechanics allows the universe to unfold in an infinite number of ways.
Hugh Everett's “many-universes” interpretation of Quantum Mechanics ("Relative State Formulation of Quantum Mechanics", 1957) states, basically, that if something physically can happen, it does: in some universe. Everett interpreted quantum "possibilities" as actualities. A particle "is" in many places at the same time: those places are in different universes. Physical reality consists of a collection of universes: the “multiverse”. We exist in one copy for each universe and observe all possible outcomes of a situation. It is not only the universe that splits into many universes, it is also the observer who splits into many observers. For a particle there is no wave of possibilities: each possibility is an actuality in one universe. (Alternatively, one can say that there is one observer for each possible outcome of a measurement).
Each measurement splits the universe in many universes (or, as Michael Lockwood puts it, each measurement splits the observer). Biographies form a branching structure, and one which depends on how often they are observed.
No reduction/collapse occurs. The wave function evolves in a deterministic way, just like in Newton's physics.
Naturally, the observer perceives exactly what I am perceiving: a flow of smooth changes.
There is an alternative way to present Everett's ideas. Everett basically accepts that the Schroedinger equation is all there is. The world is described by that equation. We have to take it literally. The particle is in all the states that the equation prescribes. The trick is that the state of the observer is as superposed as that of the observed system. Therefore the observer sees all of the possible states of the observed system. This way the world does not split, but the mind of the observer does. Each mind observes only one state of the many that are possible according to the Schroedinger equation. Therefore each mind perceives a separate world, that is a subset of the world described by the Schroedinger equation. In a sense, each mind views the world from a subjective perspective. The objective state of the world is the one described by the equation, and it corresponds to the superposition of all the states observed by all the minds of the observer.
The British physicist Stephen Hawking is even trying to write down the wave function of the universe, which will actually describe an infinite set of possible universes. Basically, he looks at the universe as if it were one big particle. Just like the wave function of a particle describes an infinite set of possible particles, the wave function of the universe actually describes an infinite set of possible universes.
In Everett's multiverse, Quantum Theory is deterministic and the role of the observer is vastly reduced (we really don't need an observer anymore, since the wave collapses in every single universe, albeit in different ways). Quantum Theory looks more like classical theory, except for the multiplication of universes.
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