Introduction and interview
by Cate Montana

For decades, the question of why quantum effects apparently break down for classical Newtonian objects (you, me, pencils and Cuisinarts) has been a puzzle for physicists. Particularly vexing has been the question of superposition.

The famous double-slit experiment has yielded consistent evidence that atoms, electrons, photons, even molecular conglomerates as large as 70 carbon atoms, can be in superposition, or in other words, simultaneously in two places at once. When any one of these small particles, let’s say a photon, is fired one at a time at the barrier with the slits at intervals sometimes exceeding an hour, it creates an interference pattern on the recording plate such as the one on the bottom of the pictures. (see “observed” pattern). This pattern could only occur if the single photon passes through both slits simultaneously, actually interfering with itself once on the other side of the barrier.

Double slit experiment. Click image for a larger view. Photos Courtesy of Wickipedia

The question physicists ask is, if photons and other quantum particles can be in two places at once, why can’t we?

So far there are several explanations. The popular Copenhagen interpretation says that any measurement or other “observation” by a human collapses the wave function of any given particle’s superposition into one manifested position. We “see” the world through our macroscopic senses every moment. Our observation instantaneously collapses any other potentials than the one we are perceiving. Voila, no superposition.

The “many worlds” theory adopts a different approach, saying that it is not observation which collapses the wave function into one “reality,” but that the superpositions move into alternative realities and manifest in parallel universes. If we used the Schrodinger’s

Cat thought experiment (which was developed to show how ridiculous the Copenhagen interpretation really was when taken to its logical classical conclusion) as the example, the many worlds theory results in two cats in two different universes, one alive and the other very much dead.

A third popular theory is decoherence, which basically says that any interaction between a quantum system and a classical system will erode the quantum system and cause it to lose its quantum properties.

In the early 1990s, a theory was put forward by Sir Roger Penrose that takes a totally different approach as to why classical objects do not exhibit quantum effects. Contrary to popular wisdom, Penrose chose to investigate gravity, which has heretofore been ignored because it is a much weaker force than electromagnetism and the nuclear strong and weak forces at the quantum level. Einstein himself spent 30 years after his development of special relativity trying to figure out how to include gravity in the quantum picture and failed.

According to Penrose, there may be something called quantum gravity operating at the levels of the extremely small – the Planck Scale - which is roughly equal to 1.6 x 10 -35 m or about 10 -20 times the size of a proton. This quantum gravity, he speculates, may well induce collapse of the wave function through a process called objective reduction, which is when self-collapse of a quantum state occurs after a critical threshold in quantum gravity has been reached.

One vital aspect of objective reduction is the fact that it is non-computable. In other words, self-collapse doesn’t happen because of some algorithmic, calculable event. Rather it occurs unpredictably, which may, strangely enough, indicate that a “conscious” or proto-conscious process is occurring at the quantum level in our brains. As Penrose and research partner Stuart Hameroff, M.D. write in their article Orchestrated Reduction Of Quantum Coherence In Brain Microtubules: A Model For Consciousness?

“An essential feature of consciousness might then be a large-scale quantum-coherent state maintained for a considerable time. OR ( objective reduction) then takes place because of a sufficient mass displacement in this state, so that it indulges in a self-collapse which somehow influences or controls brain function. Microtubules seem to provide easily the most promising place for these requirements.” 1

1 Orchestrated Reduction Of Quantum Coherence In Brain Microtubules: A Model For Consciousness?
Stuart Hameroff & Roger Penrose, In: Toward a Science of Consciousness - The First Tucson Discussions and Debates, eds. Hameroff, S.R., Kaszniak, A.W. and Scott, A.C., Cambridge, MA: MIT Press, pp. 507-540 (1996)