The Dancing Wu Li Masters (13 page)

The answer, according to the orthodox view of quantum mechanics elucidated by Stapp, is that the wave function represents something that partakes of
both
idea-like and matter-like characteristics.
^*

For example, when the observed system as represented by the wave function propagates in isolation between the region of preparation and the region of measurement, it develops according to a strictly deterministic law (the Schrödinger wave equation). Temporal development in accordance with a causal law is a matter-like characteristic. Therefore, whatever the wave function represents, that something has a matter-like aspect.

However, when the observed system as represented by the wave function interacts with the observing system (when we make a measurement), it abruptly leaps to a new state. These “Quantum Leap” type transitions are idea-like characteristics. Ideas (like our knowledge about something) can and do change discontinuously. Therefore, whatever the wave function represents, that something also has an idea-like aspect.

The wave function, strictly speaking, represents an observed system in a quantum mechanical experiment. In more general terms, it describes physical reality at the most fundamental level (the sub
atomic) that physicists have been able to probe. In fact, according to quantum mechanics, the wave function is a
complete
description of physical reality at that level. Most physicists believe that a description of the substructure underlying experience more complete than the wave function is not possible.

“Wait a minute!” says Jim de Wit (where did he come from?). “The description contained in the wave function consists of coordinates (three, six, nine, etc.) and a time. How can that be a complete description of reality? Imagine how I felt when my girlfriend ran off to Mexico with a gypsy. Where does
that
show up in a wave function?”

It doesn’t. The “complete description” that quantum theory claims the wave function to be is a description of
physical
reality (as in
physics
). No matter what we are feeling, or thinking about, or looking at, the wave function describes as completely as possible where and when we are doing it.

Since the wave function is thought to be a complete description of physical reality and since that which the wave function describes is idea-like as well as matter-like, then physical reality must be both idea-like and matter-like. In other words, the world cannot be as it appears. Incredible as it sounds, this is the conclusion of the orthodox view of quantum mechanics. The physical world
appears
to be completely substantive (made of “stuff”). Nonetheless, if it has an idea-like aspect, the physical world is not substantive in the usual sense of the word (one hundred percent matter, zero percent idea). According to Stapp:

This does not mean that the world is completely idea-like. The Copenhagen Interpretation of Quantum Mechanics does not go so
far as to say what reality is “really like behind the scenes,” but it does say that it is not like it appears. It says that what we perceive to be physical reality is actually our cognitive construction of it. This cognitive construction may appear to be substantive, but the Copenhagen Interpretation of Quantum Mechanics leads directly to the conclusion that the physical world itself is not.

This claim at first appears so preposterous and remote from experience that our inclination is to discard it as the foolish product of cloistered intellectuals. However, there are several good reasons why we should not be so hasty. The first reason is that quantum mechanics is a logically consistent system. It is self-consistent and it also is consistent with all known experiments.

Second, the experimental evidence itself is incompatible with our ordinary ideas about reality.

Third, physicists are not the only people who view the world this way. They are only the newest members of a sizable group; most Hindus and Buddhists also hold similar views.

Therefore, it is evident that even physicists who disclaim metaphysics have difficulty avoiding it. Now we come to those physicists who have jumped feet first into describing “reality.”

So far our discussions have been based on the Copenhagen Interpretation of Quantum Mechanics. The unavoidable flaw in this interpretation is the Problem of Measurement. Some type of detection by an observing system is required to collapse the wave function of the observed system into a physical reality, otherwise the “observed system” does not physically exist except as an endlessly proliferating number of possibilities generated in accordance with the Schrödinger wave equation.

The theory proposed by Hugh Everett, John Wheeler, and Neill Graham solves this problem in the simplest way possible.
⁷
It claims that the wave function is a real thing, all of the possibilities that it represents are real,
and they all happen
. The orthodox interpretation of quantum mechanics is that only one of the possibilities contained
in the wave function of an observed system actualizes, and the rest vanish. The Everett-Wheeler-Graham theory says that they
all
actualize, but in different worlds that coexist with ours!

Let’s go back to the double-slit experiment again. A light source emits a photon. The photon can pass through slit one or through slit two. A detector is placed at slit one and at slit two. Now we add a new experimental procedure. If the photon goes through slit one, I run upstairs. If the photon goes through slit two, I run downstairs. Therefore, one possible occurrence is that the photon goes through slit one, detector one fires, and I run up the stairs. The second possible occurrence is that the photon goes through slit two, detector two fires, and I run down the stairs.

According to the Copenhagen Interpretation, these two possibilities are mutually exclusive because it is not possible for me to run upstairs and to run downstairs at the same time.

According to the Everett-Wheeler-Graham theory, at the moment the wave function “collapses,” the universe splits into two worlds. In one of them I run up the stairs and in the other I run down the stairs. There are two distinct editions of me. Each one of them is doing something different, and each one of them is unaware of the other. Nor will their (our) paths ever cross since the two worlds into which the original one split are forever separate branches of reality.

In other words, according to the Copenhagen Interpretation of Quantum Mechanics, the development of the Schrödinger wave equation generates an endlessly proliferating number of possibilities. According to the Everett-Wheeler-Graham theory, the development of the Schrödinger wave equation generates an endlessly proliferating number of
different branches of reality!
This theory is called, appropriately, the Many Worlds Interpretation of Quantum Mechanics.

The theoretical advantage of the Many Worlds Interpretation is that it does not require an “external observer” to “collapse” one of the possibilities contained in a wave function into physical reality. According to the Many Worlds theory, wave functions do not collapse, they just keep splitting as they develop according to the Schrödinger wave equation. When a consciousness happens to be present at
such a split, it splits also, one part of it associating with one branch of reality and the other part(s) of it associating with the other branch(es) of reality. However, each branch of reality is experientially inaccessable to the other(s), and a consciousness in any one branch will consider that branch to be the entirety of reality. Therefore, the role of consciousness, which was central to the Copenhagen Interpretation (if consciousness is associated with an act of measurement), is incidental to the Many Worlds theory.

However, the Many Worlds description of the structure of the relationship between the various branches of physical reality sounds like a quantitative version of a mystical vision of unity. Every state of a subsystem of a composite system is uniquely correlated to the states of the remaining subsystems which constitute the whole of which it is a part. (A “composite system,” in this case, means a combination of both the observed system and the observing system. In other words, every state of the observed system is correlated to a particular state of the observing system).

Said another way, the Many Worlds theory defines any particular branch of reality which might “actualize” to us as a result of an interaction of an observed system and an observing system as merely one way of decomposing the wave function which represents them both. According to this theory, all of the other states which “could have” resulted from the same interaction
did happen
, but in other branches of reality. Each of these branches of reality are
real
, and, together, they constitute all the different ways in which we can decompose the universal wave function.

In this way, the Problem of Measurement is no longer a problem. The problem of measurement, ultimately, was, “Who is looking at the universe?” The Many Worlds theory says that it is not necessary to collapse a wave function to actualize the universe. All of the mutually exclusive possibilities contained within the wave function of an observed system that (according to the Copenhagen Interpretation) do not actualize when the wave function “collapses” actually
do
actualize, but not in this branch of the universe. In our experiment, for example, one of the possibilities contained in the wave function actu
alizes in this branch of the universe (I run up the stairs). The other possibility contained in the wave function (I run down the stairs) also actualizes, but in a different branch of reality. In this branch of reality I run up the stairs. In another branch of reality I run down the stairs. Neither “I” knows the other. Both “I”s believe that their branch of the universe is the entirety of reality.

The Many Worlds theory says that there is one universe and that its wave function represents all of the ways that it can be decomposed into different possible realities. We are all together here in a big box and it is not necessary to look at the box from the outside to actualize it.

In this regard, the Many Worlds theory is especially interesting because Einstein’s general theory of relativity shows that our universe might
be
something like a large closed box and, if this is so, it is never possible to get “outside” of it.
^*

“Schrödinger’s Cat” sums up the differences between classical physics, the Copenhagen Interpretation of Quantum Mechanics, and the Many Worlds Interpretation of Quantum Mechanics. “Schrödinger’s Cat” is a dilemma posed long ago by the famous discoverer of the Schrödinger wave equation:

A cat is placed inside a box. Inside the box is a device which can release a gas, instantly killing the cat. A random event (the radioactive decay of an atom) determines whether the gas is released or not. There is no way of knowing, outside of looking into the box, what happens inside it. The box is sealed and the experiment is activated. A moment later, the gas either has been released or has not been released. The question is, without looking, what has happened inside the box. (This is reminiscent of Einstein’s unopenable watch.)

According to classical physics, the cat is either dead or it is not
dead. All that we have to do is to open the box and see which is the case. According to quantum mechanics, the situation is not so simple.

The Copenhagen Interpretation of Quantum Mechanics says that the cat is in a kind of limbo represented by a wave function which contains the possibility that the cat is dead and also the possibility that the cat is alive.
^*
When we look in the box, and not before, one of these possibilities actualizes and the other vanishes. This is known as the collapse of the wave function because the hump in the wave function representing the possibility that did not occur, collapses. It is necessary to look into the box before either possibility can occur. Until then, there is only a wave function.

Of course, this does not make sense. Experience tells us that a cat is what we put into the box and a cat is still what is inside the box, not a wave function. The only question is whether the cat is a live cat or a dead cat. But a cat
is there
whether we look at it or not. If we take a vacation before we look inside the box, it makes no difference as far as the cat is concerned. Its fate was decided at the beginning of the experiment.

This commonsense view is also the view of classical physics. According to classical physics, we get to know something by observing it. According to quantum mechanics, it
isn’t there
until we do observe it! Therefore, the fate of the cat is not determined until we look inside the box.

The Many Worlds Interpretation of Quantum Mechanics and the Copenhagen Interpretation of Quantum Mechanics agree that the fate of the cat is not determined for us until we look inside the box. What happens after we look inside the box, however, depends upon which interpretation we choose to follow. According to the Copenhagen Interpretation, at the instant that we look inside the box, one of the possibilities contained in the wave function representing the cat
actualizes and the other possibility vanishes. The cat is either dead or alive.

According to the Many Worlds Interpretation, at the instant that the atom decays (or doesn’t decay, depending upon which branch of reality we are talking about), the world splits into two branches, each with a different edition of the cat. The wave function representing the cat does not collapse. The cat is both dead
and
alive. At the instant that we look into the box, our wave function also splits into two branches, one associated with the branch of reality in which the cat is dead and one associated with the branch of reality in which the cat is alive. Neither consciousness is aware of the other.