Where Paradoxes Reign:
The strange world of quantum physics
Watching the “Oppenheimer” movie revived my interest in quantum theory. Because I’m in the middle of packing up my house and moving across the country, I don’t have much time for writing and dug out a paper that I wrote a few years ago. Since quantum physics fits with my theme of connectedness, I present it here.
In the quantum world, the fact that the universe exists at all, as actual fact not mere possibility, is not completely explained.
Nick Herbert
Newtonian physics and Euclidean geometry totally agree with the way in which we interpret and interact with the physical world. We can say that these two systems are intuitive, in the sense that we don’t have to think about which path is the quickest to take us across the street, or that we cannot walk through a closed door. When I perceive a blue plate, I can expect the plate to remain blue and not to turn red all of a sudden, in which case I would question my sanity. This certainty comes at a cost: Newtonian physics models the universe like a giant clockwork which operates in a totally mechanistic fashion. The materialistic, reductionist science of the 19th century is being criticized today from many different quarters, but it still forms the basis of how we experience everything around us: as separate observers of an objectified world.
By contrast, the realm of quantum physics offers none of the certainties we are used to. This is a strange world indeed: full of ambiguities, possibilities, and question marks. It reminds me of Alice’s experiences in Wonderland; things shift and change, very little is certain any more. While I could hardly pretend to understand what happens on the quantum level, I was quite surprised to read that scientists do not understand it, either, although for reasons exactly opposite to mine: they know too much. Werner Heisenberg, one of the founding fathers of quantum theory, points out:
The conception of the objective reality of the elementary particles has evaporated in a curious way, not into the fog of some new, obscure, or not yet understood reality concept, but into the transparent clarity of a [new] mathematics.1
At the root of the discrepancy between ordinary and quantum reality lies a strange quality which photons, electrons, even atoms possess: in quantum state, they display a dual nature of being both wave and particle at the same time. This leads to a situation most uncomfortable for scientists: in experiments, only probabilities can be predicted, not single events; a fundamental departure from classical theory. The wave-particle duality of a photon, for example, means that as long as it is not measured or observed, the photon exists as a “wave of possibilities” which means that it could be anywhere at all in space, but it is also “nowhere” because its actual presence has not yet been measured. With the aid of a mathematical formula called the wave function, a scientist can precisely determine the possible locations in which a photon could show up, but only at the moment of observation does the photon become a tiny object recognizable in a definite place. This change in the photon’s mode of existence is called the collapse of the wave function, or the quantum jump.
The Schrödinger Equation, discovered in 1935 by the Austrian physicist Erwin Schrödinger, is used to compute the many possibilities inherent in a quantum wave. But how does the transition from this state of infinite potential to our world of solid actualities take place? This question has as yet been unsolved; and to demonstrate the seeming absurdity of placing our world, where things do not just pop randomly in and out of existence, on such slippery underpinnings as the quantum state, Schrödinger himself devised a clever thought-experiment. (It should be mentioned that Schrödinger liked cats, and never planned to try out his experiment). He suggested a light- and soundproof box, inside of which is placed a device capable of emitting a single photon; a half-silvered mirror which causes the possibility wave of the photon to split in half so that one half goes through the mirror and the other half bounces off; and two photon detectors that produce an electrical signal in response to light, placed in the two paths of the wave function. In addition, a cat is placed inside the box. If detector 1 is triggered, the cat is fed; if detector 2 puts out a signal, a cyanide capsule is released and kills the cat. Once we open the box, we shall find either an alive or a dead cat, with a 50:50 chance for one or the other outcome. But as long as the box is not opened, we are dealing with a quantum situation and have to use the mathematics of quantum theory - Schrödinger’s equation, in fact - and we get valid solutions which contain combinations of both possibilities, the cat being both alive and dead at the same time. Until the box is opened, the cat must exist in a paradoxical state of suspended animation which according to quantum theory underlies the entire physical world.
Quantum randomness, of which Schrödinger’s cat is an example, is one of the features of the quantum world which deeply troubled Albert Einstein. He wrote in 1926:
Quantum mechanics is very impressive. But an inner voice tells me: it is not yet the real thing. The theory produces a good deal but hardly brings us closer to the Old One. I am at all events convinced that He does not play dice.2
Not only is the choice of which possibility a wave will collapse into, completely random, but two in every aspect identical atoms can behave in totally different ways. Although some scientists prefer the notion of randomness to that of a clockwork as the basis of the universe, as a clockwork can easily be disturbed, there are other interpretations to which I will refer later.
Two other features of the quantum wave/particle are difficult to reconcile with reality as we know it. As long as it is not observed, a quantum object like an atom or an electron exhibits no definite attributes of its own. In addition, certain attributes (which manifest when observed) are so inextricably linked in pairs that only one of them can be measured; this means that a scientist can measure the position, but not the momentum of a particle, and vice versa. Both attributes co-exist as possibilities; only one can be identified in the actual world. This is expressed in Werner Heisenberg’s famous Uncertainty Principle, formulated in 1927.
The second feature, non-locality, is perhaps the most puzzling quality of the quantum- world view. This involves the fact that quantum entities which have briefly interacted, become entangled or inseparable. Again, Einstein was unable to accept this part of quantum theory. He demanded that any realistic, unambiguous theory be local, which means that if one object should act on a second object, a signal has to travel from one to the other, with a velocity no greater than the speed of light. Together with Boris Podolsky and Nathan Rosen, Einstein proposed a thought experiment in 1935, designed to show how unrealistic the theoretical claim for phase-entangled quantum systems was. This experiment, called EPR experiment, could not be carried out in laboratories until 1970, when John Clauser and Stuart Freedman were able to confirm quantum inseparability. Later, in 1986, physicist Alan Aspect of Paris fully vindicated quantum theory with more sophisticated experiments.
Briefly stated, in laboratory EPR experiments, two photons are produced simultaneously in identical polarization states, described mathematically as phase-entangled possibility waves. (Polarization defines certain attributes of the photon which can subsequently be observed). The photons are sent off in opposite directions to distant detectors that are able to measure polarization. The decision as to which attribute should be measured is made only after the two photons are already in flight. It turns out that the chosen context for the measurement at one photon detector instantly affects the outcome of the measurement at the other, no matter how far apart they are! The experiments demonstrated convincingly that there is no local, realistic way to understand polarization correlations. As Herbert puts it:
Despite physicists’ traditional rejection of unmediated influences; despite the fact that all known interactions in physics are mediated, mitigated, and light-speed-limited; despite Einstein’s prohibition against superluminal connections; and despite the fact that no experiment has ever directly revealed a single case of faster-than-light communication ...Bell and Clauser have shown ...that unmediated, superluminal connections must exist in nature.3
This raises some fundamental questions. How can one photon “know” instantly of the measured state of its twin? If quantum reality is inseparable and entangled, why do we perceive sense reality as separate and disentangled? So far, there are no certain answers, which could very well mean that Einstein was right when he predicted that quantum theory would eventually be replaced by a more convincing, more intuitively satisfying theory. Several interpretations exist, however, which attempt to bridge the discrepancies between the reality of the sense-perceptible world and the equally real realm of quantum events.
The most widely accepted model, the Copenhagen Interpretation, first formulated by Niels Bohr, claims that the realm of atomic particles is inaccessible to human beings whose perception of the world is limited to actual phenomena. Quantum particles do exist, but are somewhat less real because they can be known only indirectly, through mathematical computations and measurements. To this, John Archibald Wheeler has added the view that only the act of observation lifts a quantum phenomenon from the state of ambiguity to that of actuality. He declared in an interview:
To the extent that it [photon] forms a part of what we call reality, we have to say that we ourselves have an undeniable part in shaping what we have always called the past… We are participators in bringing into being not only the near and here but the far away and long ago. We are in this sense, participators in bringing about something of the universe in the distant past and if we have one explanation for what's happening in the distant past why should we need more?4
What are the implications of quantum theory in terms of our consciousness and future development? I feel that it is important to grow out of the narrow Newtonian concepts. Knowing that everyday reality is connected to a strange, magical world of shape-shifting and ambiguity, makes me look at it with new eyes. Not that I expect the chair I am sitting on to suddenly disappear and pop up somewhere else - but I am more aware of the mystery which holds everything together, of the deep connection between living and inanimate, large and small, fact and potential. The objects around me seem to be more in a constant state of becoming, less static, finished.
Some scientists, philosophers, ecologists, and other thinkers speak of the interconnectedness of all beings, the importance to realize that humanity is part of a greater whole. If as recently as fifty or sixty years ago nobody questioned “Man’s” right to dominate nature, many people today see humanity’s role as that of stewardship, as being caretakers of the Earth and nature. Being the most highly advanced organisms on the planet gives us the responsibility to nurture and sustain, not the right to exploit.
Herbert, Nick. Elemental Mind. New York: Plume/Penguin Books, 1994, p. 143
Herbert, p.236
"Everything is deeply intertwingled" – Ted Nelson 1974