Current Interpretations

The myriad of interpretations of quantum theory are all attempts to explain the meaning of reality consistent with what we know about how the the quantum world behaves. All popular interpretations are consistent with quantum theory and experimental results, and acceptance of any given interpretation implies acceptance of certain consequences regarding objective reality. We will mention a few of the more popular ones, but others can be found in the references.

- The Copenhagen Interpretation denies any deep physical reality. Since elementary quanta cannot have simultaneous values for non-communiting observables, reality itself cannot be defined until a measurement is made.
- The Many Worlds Interpretation accepts the existence of an infinite number of universes (complete with physical energy like our own). Several new ones are created every time a quantum system is forced into one of its eigenstates after previously existing in a coherent superposition of any basis states.
- The Many Histories Interpretation establishes that trajectories taken by elementary quanta are obtained by ``summing over the possible histories.'' For example, in the quantum erasure experiment, the linear polarizers have changed the set of possible histories of the photons' behaviors, thus affecting the possible outcomes of the experiment.
- The Transactional Interpretation supports that the emission and absorption of energy quanta is an indivisible, fundamental event. The nature of these events, such as when and where, are determined a priori outside of time and before the transaction takes place. Note that under this interpretation, a photon absorbed by your skin from a star 1 million light years away was a predetermined event, 1 million years ago.
- The Neorealist Interpretation maintains that the world is made up of ordinary objects as we are used to, but permits that some of these object move faster than the speed of light. Consequences of this interpretation include the possibility of reverse causality.
- The No Collapse Interpretation maintains that the wavefunction describing a quantum system never collapses. We only observe and ``think'' that it has collapsed, while all the other non-measured states of the wavefunction are forever inaccessible. After the measurement, the continuing wavefunction no longer describes the probability of what can be measured. As an aside comment: the mathematics used in this interpretation begins with wavefunctions with several vector spaces involved, such as a measuring apparatus. Classical correlations emerge when one only studies the states of the apparatus. A major problem is that the mathematics needs to assume ``collapse'' theory to even begin writing down an initial wavefunction. Otherwise, each quanta has an incredibly complex past wavefunction whose components in each space are likely to posses orthogonalities, destroying quantum interference. In short, this interpretation contains initial conditions which seem inconsistent with its conclusions.

All of these interpretations require belief in realities beyond the scope of scientific experiment. This is the price paid for claiming that the formal theory of QM describes all physical processes. The ProWave Interpretation pushes quantum weirdness back into the realm of physics, and therefore does not force us to postulate and philosophize about inaccessible realities.

Thu Jan 15 19:33:34 PST 1998