cont...
Quantum theory can perhaps be divided into two fundamental descriptive
models. This situation can be traced all the way back to beginning of quantum
theory. In fact it can be traced to all the way back to the 17th century in the
dispute as the nature of light. Is light made of waves or particles? Bohr in
the first interpretive model, the Copenhagen Interpretation tells us that the
particle and wave concept are complementary descriptions of reality. They
are both correct descriptions depending on the questions we ask, or more
accurately what we choose to measure in our laboratories. I will not dispute this
point. However, I will suggest that particle ontology (ascribing more reality
content to particles rather than waves) has significant advantage in any
interpretive model.
I am very grateful to Vic Stenger for this important insight. I must confess
I resisted this Point of view for quite some time haven been brought up in
the Copenhagen school. However, in my opinion it was the adoption of Vic’s
particle Ontology that broke through the conceptual barriers in formulating the
TSQM interpretation. However, this is no way should suggest that Vic shares
any blame for any shortcomings this model may possess.
In should also be mentioned that many prominent physicists suggest that the
particle formalism of QT is a surer road to a Quantum gravity theory which is
a major hurdle yet to make in understanding reality. A major part of the TSQM
interpretation is based on the work of one such advocate, Rafael Sorkin.
So again why do we need an interpretive model? Perhaps I should mention that
some physicists are not interested in any interpretive model. These are in
the shut and calculate school of physics. They insist, we all know are to use
QT as a tool, what else is needed? I, of course, think this viewpoint is
flawed. One of the reasons for my opinion on this is that the line between
interpretive models and models predicting new physics are not hard and fast. I
believe that the TSQM interpretation may have new physics implications,
especially in our advancement to a Quantum gravity theory. But perhaps even more
fundamentally, we are a curious species, and we are driven to understand what our
equations mean. Having mere mathematical tools doesn’t fit the bill when we
use the phrase, understand in my opinion.
In this essay I will describe just one experiment which clearly (hopefully)
illustrates the assault on common sense QT seems to make. There are many,
many experiments like this which defy our common sense viewpoint but just one
will make the point.
One physicist who strongly felt that reality couldn’t be the way QT seemed
to describe it was Albert Einstein. He argued for years with Neil Bohr and
others attempting to refute the idea that QT was a complete and consistent
theory. (Of course he didn’t dispute its predictive success.) In so doing he would
propose clever thought experiments to refute the completeness of QT. Time
and time again the questions raised by these thought experiments were shown to
cause no problem for QT by Neil Bohr.
Finally Einstein in collaboration with Podolsky and Rosen proposed what came
to be known as the EPR experiment. This proposal was further developed by
John Bell, who demonstrated mathematically that a classical view of reality
predicted different results than Quantum theory. If this experiment could be
done than it would either refute or uphold Einstein’s view of QT as incomplete.
(The details of this are beyond the Technical level I have determined to be
appropriate for this essay. However, upon request I have a detailed description
of this using a simple mathematical formalism.) Some time after Einstein’s
death, thanks to the clever work of Alain Aspect this experiment was
performed. It clearly showed that QT predictions were upheld and the great Einstein
was wrong.
So what does this experiment tell us and why is it so counter intuitive?
Well briefly Einstein asked the question if you created a pair of particles and
allows them to separate by a great distance, than any measurement on one
should not affect the other. QT maintains that these particles are in an entangled
state until one or the other is measured. This means a measurement of
particle A will instantly effect the state of particle B if particle A and B have a
common origin. Interestingly this actually doesn’t imply the transfer of
information at faster than light speed (which would violate the theory of
special Relativity) because the measurement records are random and only by
comparing the measurement records of A and B do we see the instantaneous
correlations required by QT.
So how can such a counter intuitive result be explained. We can postulate
instantaneous signaling across space time, superluminal effects. We can deny the
reality of everything except the measurement event itself or we can
postulate what are called advanced effects (time reversed) which can explain EPR
without invoking superluminal signaling. On this last proposal the TSQM
interpretation is based.
Why is this third interpretive response superior to the other two? Basically
because unlike superluminal signaling or measurement ontology, time symmetry
is a fundamental principal of all our equations. In fact it’s the existence
of an arrow of time that is problematic in physics. For this reason invoking
a time symmetric answer to this question is by far, the most parsimonious
choice.
Now finally we come to the actual TSQM interpretation. To understand this
model some basic understanding of the Feynman sum over histories is required.
This involves a very complex mathematical formalism but the basic idea is
simple.
In classical physics we can predict the path a particle takes with great
precision if we know the initial conditions with great accuracy. This is not
true for a quantum particle. In fact there is a finite probability for an
infinite numbers of paths. (This illustrates the Mathematical difficulty of SOH
which is formalized using a partition function described in a complex functional
integral. SOH is space time formalism and strongly suggest a discrete space
time. This together with its retention of time in its formalism even when
geometries are being summed over makes it potentially useful in a future quantum
gravity theory. However, this is well beyond the scope of this essay. )
However in this formalism summation of particle paths near classical
trajectories have reinforcing phase angles along the paths corresponding near
classical trajectories. This correspondence with classical description makes the
SOH formalism sensible.