Redefining Reality - The Intellectual Implications of Modern Science

is a particle, then the slits would act like shotguns, spewing
light particles at random angles. There would be no light and
But if we then turn on the photodetectors and test the second
approach, it is a particle.
If we do not have the photodetectors on, then we are not testing
for position. The result is a superposed state of both possible
positions. But when we plug the detectors in, we are observing
position, and the effect of the observation is to collapse
position. But that value is random, not predictable. Thus, the
Schrödinger equation is a description of reality when we are
not looking at it but fails whenever we check.
Three main pictures of reality are suggested by this theory.
John von Neumann contends that the superposed state is real,
we measure. The act of measuring causes a disturbance that
collapses the wave function into a single value. Measurement
is a physical act that changes the system, and this is what
causes the change from the results of the Schrödinger equation
to the random results we see.
Eugene Wigner proposed that the collapse occurs when the
system interacts with the human mind. It is our consciousness
that affects the system.
According to the picture proposed by Hugh Everett, when a
system is not observed, it is simultaneously in every possible
state, but once it is observed, reality splits and new subrealities—parallel
universes—are created. Every time we
observe a system, we do not collapse a wave function; rather,
we divide reality, creating multiple worlds.
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