MonoRealism Philosophy Site

Subjectivism, Reality and Quantum Physics

Subjectivism

Two articles from the Mensa Bulletin, reprinted in the August Tableaus, dealt with the supposed contradictions between quantum physics (the physics of matter and energy at the atomic and sub-atomic scales) and objective reality.

It has become popular among those who dislike objective reality to interpret quantum physics in this way. The argument is that quantum phenomena have no fixed values until they are observed; that experiments confirm that these values are truly indeterminate (i.e., not explained at a deeper level); and, therefore, that "consciousness creates reality".

At issue here is the battle between mysticism and realism: the "primacy of consciousness" versus the "primacy of things", as the philosopher Ayn Rand put it. Is it true that this battle has been decided by quantum physics, the rock on which the former stands, and the latter shatters? Not in the least.

Indeed, one wonders how intelligent people can make the fundamental errors of reason required for such conclusions. Is their desire for mysticism so great as to blind them? Are all the benefits of mysticism over realism in the past mental and physical slavery, short, brutal, and poverty-ridden lives really so attractive?

Following are my reasons for believing that quantum physics not only fails to support subjectivism, but is positive evidence of an independent, objective reality.

Physics

Beware of physicists bearing claims of finality. It seems to be an occupational habit. In the 19th century, physicists liked to gloat that all important knowledge had been discovered, and nothing remained except to dot the i's and cross the t's!

Despite the spectacular success of quantum mechanics, it remains an incomplete theory, for two reasons:

  1. Quantum mechanics is incompatible with that other great achievement of science, Einstein's theory of relativity. Both have been confirmed with high precision in their realms. Yet the two are basically incompatible. Clearly, neither theory is complete.
  2. The "standard model" of quantum physics has been remarkably successful in predicting the strangest results. Yet it depends on a large number of "free parameters": quantities which are not explained by the theory and which must be found by experiment. Physicists admit that this is unsatisfactory, and points to a deeper level of theory as yet undiscovered.

Don't misunderstand. I regard quantum physics as one of the great achievements of rationality and science. It has delved successfully into the fundamental secrets of nature further than anyone could have dreamed. Yet, given its limitations, it surely is presumptuous to claim that its victory is complete.

I recommend the Scientific American Special Issue 1991, "Science in the 20th Century", to anyone interested in more details of the achievements and limitations of quantum physics.

Quanta

The claim is made, based on Heisenberg's Uncertaintly Principle*, that quantum phenomena have no definite values until they are observed, with the implication that the act of observation creates those values. The further implication argued by subjectivists is that objective reality is an illusion, and that consciousness is primary.

Such claims betray a remarkable failure of logic: a failure to distinguish between the means of observation, and the act of observation itself. The misleading use of the words "observe" and "measure" is to blame. Quantum states do not have indefinite values which become definite when they are measured. They have indefinite values which become definite when the quanta interact in certain ways with other quanta. The means of observation are these interactions, which are going on all the time whether we are watching or not: our observations depend on them, not vice-versa! Observation is secondary, not primary.

Consider one quantum queerness: the wave-particle duality of matter and energy. There is no doubt that light, for example, propagates as a wave but carries energy as particles called photons. Even if a light source is so dim that only one photon is travelling at a time, the light still produces wave diffraction patterns when split into two paths! Now, does anyone dispute that light falling on plants on a deserted island has gone there as a wave, yet is absorbed by the leaves as photons? I suppose some people clinging to subjectivism might dispute it, but quantum physics in no way supports them. Nor does the existence of trees on deserted islands!

It is not the act of observation, nor the cognizance of consciousness, which "collapses" quantum states (as in the "collapsing" of a light wave into a photon). It is the simple, mindless interactions of matter and energy. Quanta act this way not by our permission, but because that is what they are: they are things whose nature is to travel as waves but be absorbed as particles, to have no fixed states until an appropriate interaction occurs. Throughout space and time, that is what they are doing, quantum states and "probability waves" collapsing willy-nilly every time energy is exchanged. They behave no differently when we observe them doing so, or when we don't. Otherwise the universe would fall apart!

Thus is the famous "Schroedinger's Cat" paradox* disarmed: the cat dies at a specific time, when the quantum event happens, in fact – whether a physicist is aware of it at the time or not.

As human beings with brains geared to our scale of things, we find it mind-bending to try to grasp how quanta can behave so, to visualize what they are. We have the same problem with things on the relativistic scale, for the same reason. But these are problems of visualization, not understanding: though their physical reality is extremely strange from our perspective, it remains an objective one, not a subjective one. And we can know it, measure it and use it.

Reality

Quantum physics has been developed by the scientific method, by the interplay of observations, hypotheses and experiments: by creativity tested with facts. It has achieved remarkable success, and revealed a picture of a quantum reality so bizarre that our minds are unable to grasp it fully.

And there's the rub. If consciousness is primary – if there is no cold, hard, objective reality against which false beliefs and wishful thinking batter and die – then how on earth could such a strange, counter-intuitive, alien theory have been arrived at?

No, what quantum physics reveals is not a subjective universe somehow dependent on consciousness. What it reveals is that quanta behave in ways quite bizarre to our thinking: propagating as waves but being absorbed as particles, having no fixed states until they interact with other quanta. They always act thus, because that is their nature: and sometimes, we happen to observe it. And what quantum physics demonstrates is that reality is so uncompromisingly objective that, by testing our ideas against it, we can arrive at the truth no matter how strange or alien to our minds and preconceptions it may be.

 


Footnotes

Schroedinger's Cat

"Schroedinger's Cat" is a thought experiment designed to show that if quantum mechanics is indeterminate and subjective, then that would apply not only to the quantum world, but would reach into everyday reality (Schroedinger himself proposed this as a reductio ad absurdum). Put a cat in a sealed box containing a vial of deadly gas, which is released if a quantum event (say, the decay of a radioactive isotope) occurs. You have no way of knowing what is happening until you open the box. Now, each minute there is a certain probability that the isotope will decay, and the cat will die. But this event does not actually happen until it is "observed". Therefore, neither is the cat alive nor dead: it exists in an indeterminate state until the experimenter opens the box! This paradox disappears when you realize that indeterminate quantum states "collapse" to definite values (in this case, the isotope decays) when they do, not when a human being catches them in the act by merely detecting that collapse.

Heisenberg's Uncertainty Principle

Heisenberg's Uncertainty Principle states that simultaneous precise measurement of certain pairs of quantum characteristics, such as position and momentum, cannot be done, even in principle.

With regard to position and momentum, the Uncertainty Principle states that the more accurately you measure the position of a particle, the less accurately you can measure its momentum, and vice versa. Specifically, the uncertainty in position multiplied by the uncertainty in momentum can never be smaller than h/2 , where h is Planck's Constant. The same is true of other simultaneously unknowable pairs. This limit is a fundamental property of quanta: it does not depend on how you measure the quanta, or which pairs of characteristics you are trying to measure.

 


For further discussion of quantum mechanics, see Holes in the Heart of Reason, Debates on Quantum Physics, and On the Nature of Quanta.

© 1992, 1996 Robin Craig: first published in TableAus.