The Hidden-Variable Theory of David Bohm
A handful of physicists have persisted in arguing that the
statistical nature of quantum mechanics implies that it is only really
applicable to ensembles of particles (just as an opinion poll is only
meaningful if a reasonable sample of the population has been polled). In other
words, quantum mechanics is an incomplete description of reality. They maintain
that underlying this level of indeterminacy there is an objective foundation.
The best known hidden-variables theory is that of the
physicist and philosopher David Bohm. What Bohm did was to distinguish between
the quantum particle, e.g. an electron, and a hidden ‘guiding wave’ that
governs its motion. Thus, in this theory electrons are quite clearly particles.
When you perform a two-slit experiment (see wave-particle duality), they go
through one slit rather than the other. However, their choice of slit is not
random but is governed by the guiding wave, resulting in the wave pattern that
is observed.
The main weakness of Bohm’s theory is that it looks contrived
- which it is. It was deliberately designed to give predictions which are in
all details identical to conventional quantum mechanics. His aim was not to
make a serious counterproposal but simply to demonstrate that hidden-variables
theories are indeed possible.
It is sometimes suggested that hidden-variables theories have
been ruled out by the Aspect experiment (see the EPR Paradox). This is a
misunderstanding of the experiment. What it did was to show that attempts to
explain quantum phenomena cannot retain both the principle of reality and the
principle of locality. The usual interpretation discards the principle of
reality. Hidden-variables theories, with their underlying determinism, must be
non-local, maintaining the existence of instantaneous causal relations between
physically separated entities. Such a view contradicts the simple location of
events in both classical atomism and relativity theory. It points to a more
holistic view of the quantum world. Indeed Bohm himself stressed the holistic
aspect of quantum theory in his later years, after his conversion from Marxism
to theosophy.
See also the many-worlds interpretation for another way of
understanding the implications of quantum theory.
Email
link | Feedback | Contributed by: Dr.
Christopher Southgate
Source: God, Humanity and the
Cosmos (T&T Clark, 1999)
|
