Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
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 Heisenberg’s 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 observable’s 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.
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