**Science
in Christian Perspective**

**Reality According to Quantum Mechanics**

**Richard H. Bube**

Department of Materials Science and Engineering

Stanford University

Stanford, California *94305
*

From: *JASA*
**36** (March 1984): 37-39.

"**L**ocal hidden variables theory is dead." These are the first words
of an article by theoretical physicist Fritz Rohrlich of Syracuse University.^{1} In this article he takes a look at the current state of
quantum mechanics, some of the philosophical interpretations that
have been spun off, and the current thinking of physicists themselves
that gives no support for some of the bizarre quasi-religious implications so frequently claimed, In this communication, I summarize in a
brief way some of the more significant of these inputs.

Although public recognition of the fact is low, the philosophical
implications of quantum mechanics have often been perceived at a
similar level of significance for theology as the much more popularly
aired debate between creation and evolution. The reason for this is
that the implications of quantum mechanics suggest a basic stratum
of chance events underlying all of reality, a situation that may be
conceived of as the antithesis of divine control and sovereign action
This is certainly a much more basic ground of possible conflict
between science and religion than creation and evolution, which at
least may be cast into a disagreement about mechanisms and
processes rather than about the fundamental nature of physical
reality. This so offended the religious sensitivity of Albert Einstein
that he never did accept quantum mechanics as complete,"^{2,3} and his
summary statement that "God does not play dice" has become
famous. When several attempts on the part of Einstein to point out
errors in Niels Bohr's interpretation of quantum mechanics failed,
Einstein retreated from the position that the theory was in error, to
the position that the theory was incomplete: i.e., that there were
"hidden variables" underlying the apparently chance phenomena,
which if known, would convert the theory into a deterministic one
once again.

Two kinds of hidden variable theories have been proposed. The
first of these can be called a "local hidden variables theory,"
so-called "Einstein locality," which holds that if two particles are
spatially separated, then a measurement on one of these particles in
no way affects the other. Since signals cannot travel faster than the
speed of light, if the two particles are sufficiently separated in space,
there will be no possibility of communication between them. This
form of local hidden variables theory can be experimentally tested
against quantum mechanics, since they predict different outcomes
for a suitable experiment. A suitably defined correlation S between
the two particles has been shown to be less than or equal to 2 if
hidden variables theory is adopted (the so-called "Bell's inequality"^{4}), whereas values of this correlation larger than 2 are possible
according to quantum mechanics. In 1982 experiments were carried
out in Paris using the polarization of two photons as the experimental
parameter.^{5,6} The results appear to have unambiguously refuted the
hidden variables theory satisfying Einstein locality. Hence the
opening words of this communication.

"Nonlocal hidden variables" theories have also been proposed,
first by Bohm^{7-9 }and then by others."^{10,11} They have been constructed
to give the same results as quantum mechanics, and at the present
time there is no way to distinguish between nonlocal hidden variables
theories and quantum mechanics itself. As long as the nonlocal
hidden variables theories remain untestable, they do not really enter
into the meaningful realm of scientific theories. For them to achieve
this status, it must be demonstrated that they are able to account for
some experimental result that quantum mechanics is unable to deal
with. Present trends do not suggest that this deterministic nonlocal
hidden variables theory is likely to gain the advantage over the
probabilistic quantum mechanics. Indeed, quantum field theory, a
generalization of quantum mechanics developed to be consistent
with special relativity, is even more probabilistic than quantum
mechanics; e.g., in quantum mechanics one can speak of measurements at a precise time, whereas in quantum field theory one can
speak only of measurements made in finite time intervals.^{12}

Claims have been made that the new understanding of reality
afforded us by quantum mechanics either without or with nonlocal
hidden variables provides us with philosophical (and even theological) insights that we have not previously had. A number of books
have appeared proposing that the new physics provides the basis for
correlation with Eastern philosophy^{13,14} and with a holistic metaphysics that sees the universe as a single giant
organism.^{15} Nobel
Laureate Eugene Wigner has sought to relate physical reality to
human consciousness.^{16 }it is appropriate that we stop and ask for the
best assessment of these claims at the present time.

*
1. Quantum mechanics applies to aspects of reality that are not
part of our everyday experience.
*
Although most of this experience
deals with the microscopic atomic and nuclear aspects of reality, it is
not limited to these aspects: phenomena in superconductivity and superfluidity, as well as the quantum phenomena measured in the
Paris experiments, can be observed in the macroscopic world. Just as
the realization of the finiteness of the speed of light, c, caused us to
make major changes in our everyday thinking about reality (such
concepts as simultaneity and addition of velocities), the realization
of the finite value of Planck's constant, *h > 0, *causes us to make
major changes in our everyday thinking about quantum reality.

*
2. Physical theories are approximate descriptions of reality with
limited validity.
*
Sometimes this range of validity appears to encompass most of our macroscopic experience, and it is hard to accept the
fact that it does not also encompass areas beyond our macroscopic
experience. We must be prepared to accept the fact, however, that
pictures and descriptions adequate for everyday experience may well
not be adequate at all for areas of reality beyond everyday experience.

*
3. The quantum world differs from the everyday world (commonly called "the classical world") qualitatively as well as quantitatively.
*
The basic particles of the quantum world, such as electrons,
protons, photons etc., cannot be distinguished one from another.
There is no way that we can label a particular electron and follow it;
all electrons look alike-they are indistinguishable. Common language derived from our everyday experience often fails us in the
quantum realm; classically we know what "particles" are and what
"waves" are, but we do not know what an "electron" is, which
sometimes behaves "just like a particle" and sometimes "just like a
wave" depending on the experimental situation.

*
4. In order for us to measure the quantum world effects we must
use a "classical" apparatus.
*
We arrive at a measurement of
quantum effects only after the quantum effects have left a permanent record in our classical measuring apparatus, e.g., a visible track
on a photographic plate due to the passage of an electron. Human
evaluation of this observation through the human consciousness
occurs last of all and totally within the classical domain. It does not
seem possible, therefore, for the human consciousness to play any
role in determining the behavior of the electron itself.

*
5. The measuring apparatus plays a significant role in the total
experimental system.
*
Unlike the classical situation, where the
measuring apparatus can be considered almost totally independent
of the effect being measured, in the quantum realm the system apparatus interaction can play an important role.

*
6. Unlike the classical system for which all observables can be
known at the same time with arbitrary precision (in principle), each
quantum system is characterized by a set of observables that can be
known with arbitrary precision and another set of observables that
cannot.
*
The latter can occur with various different values; which of
these values will occur in a measurement is precisely given by a
probability distribution. An imperfect analogy is given by the sum of
the faces of two dice; this sum can take on a variety of different
values and the probability of a given value for the sum can be
precisely given by a probability distribution (we know, for example,
that the sum "T' will occur six times more often than the sum "T' or
" 12"). If we consider two observables, one from the set that can be
known (e.g., momentum if the system is in a given energy state), and
one from the set that cannot be known (e.g., position), it follows that
both momentum and position cannot be precisely known-leading to
the well known Heisenberg Indeterminacy Principle. An analogy is
given by our inspection of a famous masterwork painting: if we use a
high power magnifying glass to look at the details of the brush
strokes, or if we use our eyes when standing back a distance of 10
feet, we get different information in the two cases, which cannot be
obtained simultaneously. Both pieces of information are necessary to
describe the painting totally; they are said to be "complementary."
^{
17}

*
7. Changes in the state of a quantum system are not described in
a probabilistic mode: the state of the system changes according to
the deterministic Schroedinger equation and is uniquely given by
the knowledge of its initial state.
*
If interactions occur between this
system and another system, then of course changes occur that can be
calculated only by taking into account both systems and their mutual
interaction. When a system changes, then in general so do the set of
observables that can be determined with arbitrary precision. A
measurement constitutes such an interaction.

*
8. Our inability to know precisely is not the consequence of our
inability or imperfection, but rather simply because the requested
information is not present in the particular state of the system.
*
This
occurs when the observable has a distribution of values in that state
of the system, rather than being capable of precise determination.
This distribution can indeed be known precisely.

*
9. The major difference between a quantum probability distribution and a classical probability distribution is that the quantum
distribution is the square of a sum of probability amplitudes
(coherent superposition of states) whereas the classical distribution
is a sum of the squares of probability amplitudes (incoherent
superposition),
*
i.e., quantum: (A + B + C)' vs classical: (A
2 +
*B *
2
+ C'). This fact means that in the quantum case it is possible that
the probability for two different values of an observable to occur can
interfere with one another, something that is impossible in the
classical case. It is this interference that accounts for the difference
between the local hidden variables interpretation and the quantum
mechanical interpretation of the Paris experiments.

*
10. The situation that an observable has a distribution of values
will be encountered whenever we measure an observable that does
not have precise values in a particular system.
*
The system and the
measuring equipment enter into interaction according to the quantum mechanical treatment until finally one of the states of the
system being measured leaves a permanent record in the measuring
equipment," e.g., a photographic track or a needle position. This
position cannot be predicted for a single experiment, but the precise
relative probabilities for all pointer positions can be calculated from
quantum mechanics and can therefore be checked experimentally in
a large number of measurements. Our imperfect analogy of throwing
dice can again be invoked; before the dice are thrown the probability
of obtaining a "T' is 6/36, but after the dice are thrown the
probability reduces to either I (a "T' is thrown) or 0 (a "T' is not
thrown).

*
11. Reality is not created by the measurement.
*
A quantum
mechanical system exists in a real state before the interaction with
the measuring equipment. Two dice are real before they hit the table.
Reality is not created by the observation; the system is present all the
time. The claim that quantum mechanics requires us to believe that
the universe does not actually exist "out there" independent of the
observer, but rather is created by the observer, has no necessary
support from quantum mechanics.

*
12. There are certain questions about quantum mechanical
systems that have no answers.
*
We can be seriously misled by our
efforts to describe quantum mechanical effects using words from
common experience that do not apply. The question of where the
photon comes from when a electron drops from an excited state to
the ground state of the hydrogen atom, for example, has no answer.
An analogy would be the calculation of reflection from a highly
absorbing medium using the classical wave model for light; the
model gives accurate values for the reflection but is totally incapable
of answering questions about what happens in the material to cause
reflection. To get meaningful answers of a scientific model, one must
ask questions consistent with the nature of that model. If we insist
that quantum mechanics must supply the same kind of answers as
classical physics, we have made the decision that classical question
answering must be normative.

*
13. Physical reality on the quantum level cannot be defined in
classical terms.
*
The world of electrons, protons, photons etc. exists
"out there" quite independent of us, and behaves (as far as we know
today) exactly the way that quantum mechanics describes. The
addition of probability amplitudes characteristic of quantum
mechanics, rather than the addition of probabilities characteristic of
classical physics, constitutes a qualitative difference between the
classical and quantum worlds. This difference must be accepted as
indicative of the actual properties of the natural world at the
quantum level, just as the universal constancy of the speed of light is
accepted as indicative of the actual properties of the natural world at
the relativistic level. There is no known scientific reason today that
would cause one to deviate from this position.

^{1}Fritz Rohrlich, "Facing Quantum Mechanical Reality,"
*Science 221, *
No.
4617, 1Z51 (1983).

^{6}A. Aspect, J.
Delibard, and G. Roger,
*Phys. Rev. Lett. *
49,1804 (1982).

^{7}D.
Bohm,
*Phys. Rev. *
85, 166, 180 (1982).

^{8}D. Bohm,
*Causality and Chance in Modern Physics, *
Van Nostrand, Princeton, N.J. (1957).

^{9}D. Bohm,
*Wholeness and the Implicate Order, *
Routledge and Kegan Paul,
London(1980).

^{10}For a review see
F.J. Belinfante,
*A Survey of Hidden Variables Theories,
*
Pergamon, N.Y. (1973)~

^{11}For a review see M.Jammer,
*The Philosophy of Quanturn Mechanics, *
John
Wiley & Sons, N.Y. (1974).

^{
14} G. Zukav,
*The Dancing Wu-Li Masters: An Overview of the New Physics,
*
Morrow, New York (1979).

^{15}V.S. Owen,
*And the Trees Clap Their Hands, *
Eerdmans, Grand Rapids,
Michigan (1983).

^{16}E.P.
Wigner,
*Symmetries and Reflections, *
Indiana Univ. Press, Bloomington,
(1967).

^{17}JW. Haas, Jr., "Complementarity and Christian
Thought-Xn Assessment,"
*journal ASA *
35,145, 203 (1983); R.H. Babe, "The Appeal (the Necessity?)
of Complementarity,"
*journal ASA *
35, 240 (1983).