"The universal wave function describes the position of every particle in the Universe at a particular moment in time. But it also describes every possible location of every particle at any other instant of time, although the number of possibilities is restricted by the quantum graininess of space and time. Out of this myriad of possible universes, there will be many versions in which stable stars and planets, and people to live on those planets cannot exist. But there will be at least some universes resembling our own, more or less accurately… .
That isn't the end of it. The single wave function describes all possible universes at all possible times. But it doesn't say anything about changing from one state to another. Time does not flow. Sticking close to home, Everett's parameter, called a state vector, includes a description of a world in which we exist, and all the records of that world's history, from our memories, to fossils, to light reaching us from distant galaxies, exist. There will also be another universe exactly the same except that the 'time step' has been advanced by, say, one second (or one hour, or one year). But there is no suggestion that any universe moves along from one time step to another. … Different time states can be ordered in terms of the events they describe, defining the difference between past and future, but they do not change from one state to another. All states just exist. Time, in the way we are used to thinking about it, does not 'flow' in Everett's MWI."
(Gribbin, pp64-5)
The Many Worlds Interpretation is often presented as the interpretation that removes mystery by refusing collapse. Nothing ever jumps, nothing is selected, nothing is destroyed. The wavefunction evolves smoothly and universally. What could be cleaner?
The quote above shows why this cleanliness comes at a very particular cost.
From parsimony to proliferation
The universal wavefunction is introduced as a single, elegant object: a complete description of every particle in the Universe. But almost immediately, elegance turns into abundance. The wavefunction does not merely describe what exists; it describes every possible configuration at every possible time. From this space of possibilities, entire universes emerge—most of them sterile, some habitable, a few resembling our own closely enough to host observers who ask these questions.
This is not excess by accident. It is excess by necessity. Once collapse is ruled out, differentiation can only occur by multiplication. The interpretation pays for dynamical simplicity with ontological proliferation.
Time without passage
The strain deepens when time is addressed. The universal wavefunction contains all possible temporal states, but it contains no transition between them. There is ordering without motion, succession without passage. Worlds differ by their time index, but none of them move.
What we ordinarily call the flow of time—change, becoming, persistence—is re-described as a static array of complete histories. Memory, fossils, and light from distant galaxies are not traces of a past that led to a present; they are internal features of particular world-states.
The result is a Universe in which everything happens, but nothing happens to anything.
Where the work is being done
As with earlier interpretations, the explanatory burden has not vanished; it has shifted. The work once done by collapse is now done by:
an unimaginably vast space of coexisting universes,
a timeless ordering of complete world-states,
and an implicit reliance on perspectival location to explain why this history is experienced rather than any other.
The mystery of selection has not been eliminated. It has been deferred to the standpoint of the observer, now reinterpreted as one branch among uncountably many.
Excess as diagnosis
The Many Worlds Interpretation is often described as extravagant because it posits too many universes. But the real extravagance lies elsewhere. It lies in the attempt to preserve an object-based, time-indexed ontology while refusing any mechanism that would actualise one outcome rather than another.
With collapse forbidden and instantiation treated as a physical process that must not occur, the only remaining option is to let everything exist.
Clearing the fog
From a relational perspective, the difficulty is familiar by now. A theory of potential is being treated as a catalogue of realities. The universal wavefunction, construed as a theory of possible instantiations, is mistaken for a description of what is equally the case.
Once instantiation is understood as a perspectival cut rather than a transition through time, the need for proliferating worlds evaporates. Possibility does not require duplication. Ordering does not require flow. And explanation does not require that every potential be ontologically honoured.
What the Many Worlds Interpretation reveals, with remarkable clarity, is how far one must go to avoid letting instantiation do its quiet work.
That is not a failure of imagination.
It is a diagnosis.
No comments:
Post a Comment