The real death knell for Newtonian mechanics as a universal theory was sounded by Albert Einstein, Erwin Schrödinger, Werner Heisenberg and other scientists that stood at the cradle of quantum mechanics in the early 20th century. The behaviour of “elementary particles” could not be explained by classical mechanics. A new mathematics had to be developed.

In this mathematics there are concepts like a “phase-space” wherein a system is defined as a point which has its degrees of freedom as coordinates, and “operators”, magnitudes that are incompatible with algebraic magnitudes in the sense that they are more similar to operations than to magnitudes themselves (in fact they express relations instead of fixed properties) play a significant role. Probability also plays an important role, but in the sense of “intrinsic probability”: it is one of the essential characteristics of quantum mechanics. In fact quantum mechanical systems must be interpreted as the superposition of all the possible pathways they can follow.

Quantum particles can only be defined as a set of internal relationships between their “actual” and its “virtual” state. In that sense they are purely dialectical. Measuring those particles in one way or another leads only to the revealing of the “actual” state, which is only one aspect of the whole (this paradox is popularly explained by the tale of “Schrödinger’s cat”). It is called the “collapse of the wave function”, and is expressed by the uncertainty principle of Heisenberg. This entirely new way of looking toward physical reality, which is expressed by quantum mechanics, was kept “in quarantine” for a long time by the rest of the scientific disciplines. It was seen as an exceptional kind of mechanics, only to be used in describing the behaviour of elementary particles, the exception to the rule of classic mechanics, without any importance whatsoever.

In place of the old certainties, uncertainty now reigned. The apparently random movements of subatomic particles, with their unimaginable velocities, could not be expressed in terms of the old mechanics. When a science reaches a blind alley, when it is no longer able to explain the facts, the ground is prepared for a revolution, and the emergence of a new science. However, the new science, in its initial form, is not yet completely developed. Only over a period does it emerge in its final and complete form. A degree of improvisation, of uncertainty, of varying and often contradictory interpretations, is virtually inevitable at first.

In recent decades a debate has opened up between the so-called stochastic (“random”) interpretation of nature and determinism. The fundamental problem is that necessity and chance are here treated as absolute opposites, mutually exclusive contraries. In this way, we arrive at two opposing views, neither of which is adequate to explain the contradictory and complex workings of nature.

Werner Heisenberg, a German physicist, developed his own peculiar version of quantum mechanics. In 1932, he received the Nobel Prize for physics for his system of matrix mechanics, which described the energy levels of orbits of electrons purely in terms of numbers, without any recourse to pictures. In this way, he hoped to get round the problems caused by the contradiction between “particles” and “waves” by abandoning any attempt to visualise the phenomenon, and treating it in a purely mathematical abstraction. Erwin Schrödinger’s wave mechanics covered exactly the same ground as Heisenberg’s matrix mechanics without any need to retreat into the realms of absolute mathematical abstraction. Most physicists preferred Schrödinger’s approach, which seemed far less abstract, and they were not wrong. In 1944, John von Neumann, the Hungarian-American mathematician, demonstrated that wave mechanics and matrix mechanics were mathematically equivalent, and could achieve exactly the same results.

Heisenberg achieved some important advances in quantum mechanics. However, permeating his whole approach was the determination to inflict his peculiar brand of philosophical idealism upon the new science. From this arose the so-called Copenhagen interpretation of quantum mechanics. This was really a variety of subjective idealism, thinly disguised as a school of scientific thought. “Werner Heisenberg,” wrote Isaac Asimov, “proceeded to raise a profound question that projected particles, and physics itself, almost into a realm of the unknowable.”[5] That is the correct word to use. We are not dealing here with the unknown. That is always present in science. The whole history of science is the advance from the unknown to the known, from ignorance to knowledge. But a serious difficulty arises when people confuse the unknown with the unknowable. There is a fundamental difference between the words “we do not know” and “we cannot know”. Science sets out from the basic notion that the objective world exists and can be known to us.

However, in the whole history of philosophy there have been repeated attempts to place a limit upon human cognition, to assert that there are certain things which “we cannot know”, for this reason or that. Thus Kant claimed that we could only know appearances, but not Things-in-Themselves. In this, he was following in the footsteps of the scepticism of David Hume, the subjective idealism of Berkeley and the sophists: that we cannot know the world.

In 1927, Werner Heisenberg advanced his celebrated “uncertainty principle”, according to which it is impossible to determine, with the desired accuracy, both the position and velocity of a particle simultaneously. The more certain a particle’s position, the more uncertain its momentum, and vice versa. (This also applies to other specified pairs of properties.) The difficulty in establishing precisely the position and velocity of a particle that is moving at 5,000 miles per second in different directions is self-evident. However, to deduce from this that cause and effect (causality) in general does not exist is an entirely false proposition.

How can we decide on the position of an electron? he asked. By looking at it. But if we use a powerful microscope, it would mean striking it with a particle of light, a photon. Because light behaves like a particle, it will inevitably disturb the momentum of the observed particle. Therefore, we change it by the very act of observation. The disturbance will be unpredictable and uncontrollable, since (at least from the existing quantum theory) there is no way of knowing or controlling beforehand the precise angle with which the light quantum will be scattered into the lens. Because an accurate determination of the position requires the use of light of short wavelength, a large but unpredictable and uncontrollable momentum is transferred to the electron. On the other hand, an accurate determination of the momentum requires the use of light quanta of very low momentum (and therefore of long wave-length), which means a large angle of diffraction, and hence a poor definition of the position. The more accurately the position is defined, the less accurate the momentum can be defined, and vice versa.

So can we get round this problem if we develop new kinds of electron microscopes? Not according to Heisenberg’s theory. Since all energy comes in quanta, and all matter has the property of acting both as a wave and a particle, any type of apparatus we use will be governed by this principle of uncertainty (or indeterminacy). Indeed, the term uncertainty principle is inexact, because what is asserted here is not just that we cannot be certain, because of problems of measurement. The theory implies that all forms of matter are indeterminate by their very nature. As David Bohm says in his book Causality and Chance in Modern Physics:

Thus the renunciation of causality in the usual interpretation of the quantum theory is not to be regarded as merely the result of our inability to measure the precise values of the variables that would enter into the expression of causal laws at the atomic level, but, rather, it should be regarded as a reflection of the fact that no such laws exist.

Instead of seeing it as a special aspect of quantum theory at a particular stage in its development, Heisenberg postulated indeterminacy as a fundamental and universal law of nature, and assumed that all other laws of nature would have to be consistent with it. This is completely different to the approach of science in the past when it was confronted with problems related to irregular fluctuations and random movement. No-one imagines it is possible to determine the exact motion of an individual molecule in a gas, or predict all the details of a specific car accident. But never before has a serious attempt been made to derive from such facts the non-existence of causality in general.

Yet this is precisely the conclusion we are invited to draw from the principle of indeterminacy. Scientists and idealist philosophers have gone on to argue that causality in general does not exist. That is to say, that there is no cause and effect. Nature thus appears as an entirely causeless, random affair. Bohm argued that the entire universe is unpredictable.

We cannot be certain of anything. Instead, it is assumed that in any particular experiment, the precise result that will be obtained is completely arbitrary in the sense that it has no relationship whatever to anything else that exists in the world or that ever has existed.[6]

This position is the complete negation, not only of science, but of rational thought in general. If there is no cause and effect, not only is it impossible to predict anything; it is impossible to explain anything. We can only limit ourselves to describe what is. In fact, not even that, since we cannot even be certain that anything exists outside ourselves and our own senses. This brings us right back to the philosophy of subjective idealism. It reminds us of the argument of the sophist philosophers of ancient Greece: “I cannot know anything about the world. If I can know something, I cannot understand it. If I can understand it, I cannot express it.”

What the “indeterminacy principle” really represents is the highly elusive character of the movement of subatomic particles, which are not susceptible to the kind of simplistic equations and measurements of classical mechanics. There is no doubt about Heisenberg’s contribution to physics. What is in question is the philosophical conclusions which he drew from quantum mechanics. The fact that we cannot measure exactly the position and momentum of an electron does not imply in the slightest that there is a lack of objectivity here. The subjective way of thinking permeates the so-called Copenhagen school of quantum mechanics. Niels Bohr went so far as to state that “it is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.”

The physicist John Wheeler maintains that “no phenomenon is a real phenomenon until it is an observed phenomenon.” And Max Born spells out the same subjectivist philosophy with absolute clarity:

The generation to which Einstein, Bohr, and I belong was taught that there exists an objective physical world, which unfolds itself according to immutable laws independent of us; we are watching this process as the audience watches a play in a theatre. Einstein still believes that this should be the relation between the scientific observer and his subject.[7]

What we have here is not a scientific evaluation, but a philosophical opinion reflecting a definite world outlook – that of subjective idealism, which permeates the entire Copenhagen interpretation of quantum theory. A number of eminent scientists, to their credit, made a stand against this subjectivism, which runs contrary to the whole outlook and method of science. Among these were Albert Einstein, Max Planck, Louis de Broglie and Erwin Schrödinger, all of whom played a role in developing the new physics at the very least as important as Heisenberg.

  1. Asimov, I. New Guide to Science, p. 375.

  2. Bohm, D. Causality and Chance in Modern Physics, pp. 86 and 87.

  3. Ferris, T. The World Treasury of Physics, Astronomy, and Mathematics, pp. 103 and 106.