These are excerpts and elaborations from my book "The Nature of Consciousness"
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The Discontinuity Of Time One of Newton's postulates was that "time
flows equably". The biggest
problem with Quantum Theory is how the observed world (the world we know, made
of well-defined objects) emerges from the quantum world (a world of mere
possibilities and uncertainties, thanks to Heisenbergs principle). The Hungarian
mathematician John Von Neumann (the same one who invented the computer) distinguished between
processes of the first and second kinds that occur when one is analyzing the
evolution of a system with Quantum Theory. First-kind processes occur in
isolated systems, on which no measurements can be carried out, and they closely
resemble classical, deterministic evolution of a physical system. Second-kind
processes occur when a measurement is carried out and they are
non-deterministic (or at least probabilistic): when an observable is measured,
the state of the system suddenly jumps to an unpredictable state (or
eigenstate) associated with the measured eigenvalue of the observable. Unlike
classical Physics, in which the new state can be determined from the prior
state of the system, Quantum Theory can only specify the probabilities of
moving into any of the observables eigenstates. In quantum lingo, a
measurement causes a collapse of the wave function, after which the
observable assumes a specific value. A continuous process of the first kind
gives rise to a discontinuous process of the second kind. Isolated systems
obey the Schroedinger equation, observed systems obey Heisenberg's quantum jumps. Quantum Theory
therefore implies that something turns a process of the first kind into a
process of the second kind when it is observed. The problem is
that Quantum Theory does not prescribe or describe when and how this happens.
The flow of time is mysteriously altered by measurements: a system evolves in a
smooth and deterministic fashion until a measurement is performed, then it
jumps more or less randomly into an eigenstate of the measured observable, from
where it resumes its smooth evolution until the next measurement. Time seems to
behave in an awkwardly capricious way. As Bohr pointed out, a measurement also introduces irreversibility in nature: collapse cannot be undone. Once we measure a quantity, a discontinuity is introduced, at that point in time, in the evolution of the wave function. If, after a while, we proceed backwards in time, we would reach the same point from the future with a wave function which could collapse into any of the legal ways, only one of which is the one that originated the future we are coming from. It is very unlikely that we would retrace the same past. Thus there is
another arrow of time (besides entropy) that explains why time only flows in
one direction. Back to the beginning of the chapter "The New Physics" | Back to the index of all chapters |
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