The Copenhagen interpretation Born, Heisenberg, Schrödinger, Bohr ( ) Even though the Copenhagen interpretation is supposed to be the “orthodox” interpretation, there is widespread disagreement on it because… …it requires a process (called wavefunction collapse) for which there is no known physical explanation. The disagreement is between those who believe a physical explanation might be possible and those who don’t.

In this interpretation… Space and time are assumed to be objectively real. Prior to an observation, the universe is assumed to be divided between a quantum wavefunction that cannot be observed and a classical object that can be observed.

The wavefunction is assumed to be a solution to the Schrödinger equation, the fundamental equation of quantum physics The wavefunction is assumed to exist whether or not there are observations. It represents the probability (not the certainty) that a specific result (e.g., a position) will be obtained if the observer makes a specific type of measurement (e.g., of position). It describes all of the possible results (e.g., all of the possible positions) that could be obtained, but cannot predict which result will actually be obtained.

Wavefunction collapse At the moment of observation, the wavefunction is assumed to change irreversibly from a description of all of the possibilities (e.g., of position) that could be observed to a description of only the event that is observed. This is called wavefunction reduction, or wavefunction collapse.

The next observation After an observation and wavefunction collapse, a new wavefunction emerges. It represents all of the possibilities that are allowed by the previous observation. Another observation results in another wave function collapse, etc. In this interpretation, a sequence of observations result from a sequence of wavefunction collapses. Without wavefunction collapse, there are no observations.

Wavefunction collapse (cont.) Any solution to the Schrödinger equation must at all times contain as many possibilities as were present initially. No mechanism that obeys the Schrödinger equation (i.e., no physical process) can change the number of possibilities. This means that no physical process can cause collapse. Thus, collapse requires a nonphysical agent.

What is the only nonphysical agent that we know of? Most physicists do not like to admit that collapse might be caused by Awareness. Awareness, being nonphysical, does not obey the Schrödinger equation. Therefore, Awareness might collapse the wavefunction.

Wavefunction collapse (cont.) Even if there were a physical mechanism for wavefunction collapse, it would produce nothing but a collapsed wavefunction. A collapsed wavefunction is not aware. It is only a collapsed wavefunction. Awareness exists on a different level from the objects of awareness. What “we” are aware of cannot be what is aware. Awareness is self-evident. It needs no proof. That “we” are aware is the only thing that “we” can be certain of because Awareness does not change. All objects of Awareness change with time.

The problem of the observer What do we mean by an observer? In the Copenhagen interpretation, a sequence of observations results from a sequence of wavefunction collapses. An example of a sequence of observations is a sequence of thoughts, feelings, emotions, body sensations, and perceptions, i.e., a sequence of mind states. (These can be thought of as a sequence of arisings in Awareness.)

The Copenhagen interpretation does not require separate observers It requires only observations. The separate “observer” is only a mental construct (which could result from a sequence of wavefunction collapses).

If there are observations but not separate observers… There is no separation… …and there is no suffering. “We” think there is more than one “observer” because “we” have been taught so. Suppose “we” have been taught wrong! Then the best thing “we” can say about all of “our” suffering is that it has told “us” that there must be a better way!

The Copenhagen interpretation could be purely subjective The Copenhagen interpretation normally requires an objective wavefunction that collapses at the moment of an observation. However, suppose there is no wavefunction and no wavefunction collapse. Then an observation would consist of simply a sequence of mind states. This would be a purely subjective interpretation.

For example, Christopher Fuchs has created a subjective interpretation in which quantum probabilities are interpreted as Bayesian probabilities. Bayesian probabilities are probabilities that an agent’s belief will change to a new belief as a result of new data (from new observations). At the present time, Fuchs’ interpretation requires an external object to be observed. However, if the observation were purely subjective, then his interpretation would be a completely subjective interpretation of quantum theory!