How Quantum Physics Contradicts the Belief in an Objective World Existing Independent of Observation
by Thomas J. McFarlane
The Center for Sacred Sciences was founded on the belief that the testimony of the mystics of all religions is compatible with the evidence of modern science. This compatibility, however, is often far from obvious, largely because the modern scientific tradition has attached itself to a materialistic cosmology which is inherently antagonistic to spiritual insight. This cosmology, also known as materialism, asserts that matter has independent objective existence, and that all phenomena, including those of the mind and consciousness, are ultimately reducible to the motions of matter. The development of quantum mechanics, however, has shown that materialism is actually incompatible with modern science.
The purpose of this article is to explain in detail exactly how quantum physics contradicts the materialistic account of the universe. As we will see, quantum mechanics demonstrates that the world as we commonly experience it does not, in fact, have an objective existence independent of its observation. In the words of Niels Bohr, the pioneer of 20th century quantum physics,
An independent reality, in the ordinary physical sense, can neither be ascribed to the phenomena nor to the agencies of observation.1
This remarkable claim is entirely compatible with the claims of the mystics. For example, consider the following fundamental teaching of the Center for Sacred Sciences:
The appearance of an objective world distinguishable from a subjective self is but the imaginary form in which Consciousness Perfectly Realizes Itself.2
In the same spirit, the third Chinese Zen patriarch, Sengtsan, teaches us:
Things are objects because of the subject [mind]; the mind [subject] is such because of things [object]. Understand the relativity of these two and the basic reality: the unity of emptiness. In this Emptiness the two are indistinguishable and each contains in itself the whole world.3
The mystics and physicists, therefore, both make the outrageous claim that the materialistic belief in an objective world independent of observation is a delusion. Or, in Buddhist terms, all objects are empty of any inherent existence. Since this claim is in blatant contradiction with both our ordinary experience and conventional worldly wisdom, our natural response is to dismiss it as ludicrous. We might say to ourselves, "Those mystics are obviously the deluded ones who have lost touch with reality, not me and everyone else."
Although it might be easy for a modern Westerner, raised in a materialistic culture, to dismiss the radical claims of the mystics, it is not so easy to dismiss the most eminent of our physicists, who make claims remarkably similar to those of the mystics. Consider, for example, the words of Werner Heisenberg, the inventor of quantum mechanics:
The ontology of materialism rested upon the illusion that the kind of existence, the direct "actuality" of the world around us, can be extrapolated into the atomic range. This extrapolation is impossible, however.4
The Buddha, speaking about the true nature of reality, makes the following very similar claim:
There is that which does not belong to materialism and which is not reached by the knowledge of philosophers who...fail to see that, fundamentally, there is no reality in external objects.5
If we dismiss the Buddha and other mystics, shall we also dismiss Heisenberg and Bohr? These eminent physicists won Nobel prizes for their fundamental contributions to quantum theory. Perhaps no other physicists have thought more deeply about the nature of quantum physics than Heisenberg and Bohr. And they are talking about quantum mechanics, the most precise and far-reaching physical theory ever devised. It explains how the sun shines, how molecules bond together, how iron is magnetized, and why various materials are solid, liquid, or gas. It is quantum mechanics that gives us computer chips, lasers, and atomic energy. So if we dismiss quantum mechanics, we throw out the cornerstone of modern physics and the theory that provides the essential foundation for all these scientific marvels. It seems that we had better think twice before dismissing what Bohr and Heisenberg have to say about the nature of the physical world.
Put simply, they say that the objective world is an illusion. The biggest problem with this claim is that our experience, for the most part, is quite compatible with the idea that there really is an independently existing objective world. There seems to be no contradiction at all between our normal day-to-day experience and our assumption that the objects we encounter during the day are objectively real. So the problem is, if this idea of an objective world is wrong, then why does it seem so right? To shed some light on this problem and its solution, let me digress for a moment with the following thought experiment.
Imagine going back in a time machine 3000 years and encountering some people who are convinced that the world is flat. Wishing to correct their misconception, you politely inform them that they are mistaken. In fact, you tell them, the world is not flat but round. They ask you why you believe such a crazy idea, and you become quite embarrassed when you find that you cannot show them the least bit of evidence to back it up. They, on the other hand, explain to you that it is perfectly obvious from all their experience that the earth is flat. After all, they use concepts of plane geometry to measure out land and make road maps and they never find any contradiction at all with their day-to-day experience. Nor do they see any curvature at all when they look across wide open spaces of land or sea. So your claim that the earth is round is obviously a delusion and they dismiss you as a crazy mystic (especially after you tell them about people from your time who ascend into the heavens in a blaze of fire where they can look down upon the whole created world and see that it is round). Frustrated and disappointed, you board your time machine and head back home to the present.
Figure 1: A flat earth appears flat on a small scale.
Figure 2: A round earth also appears flat on a small scale.
The reason you could not convince your friends in the past that the world is round, of course, is because you are so small in comparison to the earth. Since your experience is normally limited to a small geographical region, the earth appears flat even though it really is not. In other words, the apparent flatness of the earth is not a real flatness due to an earth that is actually flat (Fig. 1), but rather is an illusory flatness due to the large size of the earth (Fig. 2). To prove that the earth is round, you would need to go beyond your ordinary experience. For example, you could fly around the globe in an airplane, or catch a ride on the next space shuttle flight. But as long as you are confined to your ordinary experience, there is no proof that the flatness is an illusion, and no reason why you should not believe that the earth is flat.
If people have been so deluded about reality in the past, how can we be so sure that we are not deluded now? As we have seen, just because our present notions of reality are consistent with our ordinary experience, does not make them true. Since our experience certainly has its limits, perhaps our idea of the objective world really is an illusion, just as much an illusion as the idea of a flat earth. What wonders might lie beyond the limits of our present experience? What truth might lie hidden beneath our present illusions?
We can now reconcile the shocking claims of Heisenberg and Bohr with our normal experience of an objective world, and understand how the world might not have an independent objective existence, even though it appears to have one. The solution is to recognize that our experience is ordinarily limited. Because we ignore certain aspects of our experience, we typically mistake what appears to be true in this limited experience for what is actually true in all experience. Just as the belief that the world is flat is at best a useful fiction, and not at all real, the belief that the world exists objectively is also just an illusion. Of course, this fiction, like the fiction of a flat earth, is a useful one that fits much of our ordinary experience. But the moment we take it to be universally true, we slip into delusion. To break the spell of delusion, we need to depart from the limitations of the ordinary and expand our experience to include more subtle observations. Then we find that these fictions quickly unravel to reveal a very different reality.
To quote Heisenberg once more,
The existing scientific concepts cover always only a very limited part of reality, and the other part that has not yet been understood is infinite. Whenever we proceed from the known into the unknown we may hope to understand, but we may have to learn at the same time a new meaning of the word `understanding'.6
And Bohr expresses the same idea as follows:
As our knowledge becomes wider, we must always be prepared...to expect alterations in the point of view best suited for the ordering of our experience.7
Now that we have a framework for understanding how, in spite of our experience to the contrary, the objective existence of the world could be an illusion, let us now consider the quantum mechanical evidence that unravels the fiction of materialism. Keep in mind, however, that this evidence will necessarily draw from phenomena that lie outside the usual limits of our experience.
Before the 20th century, our scientific worldview was based on the laws of classical physics, which included Newton's laws of motion and Maxwell's equations. While Newton's mechanical laws governed the behavior of material particles, Maxwell's wave equations described the behavior of light. In the classical world, therefore, there were two very different types of phenomena: matter which behaved like discrete particles localized in space, and light which behaved like continuous waves spread out in space. Around the turn of the century, however, new scientific observations at the microscopic scale revealed that light sometimes behaves like particles, and matter sometimes behaves like waves!
To understand this strange paradox, let us first perform a couple of thought experiments, one to illustrate the classical behavior of particles, and another to illustrate the classical behavior of waves. Then we will compare these two thought experiments with a quantum thought experiment. So, first, let us consider classical particles. Imagine that we place a source of large particles (a sand blower, for example) behind a wall that has two slits in it (Fig. 3). On the other side of the wall is a screen which can detect the particles that have passed through the two slits. Since particles are by definition localized in space, each one is emitted from the source, travels through one slit or the other, and hits the screen. After allowing many particles to pass through the two slits and hit the screen, we observe two clusters of points on the screen: one cluster corresponding to particles that went through one of the slits, another cluster corresponding to particles that went through the other slit. A graph of the particle intensity versus position on the screen thus has the shape of two separate peaks, as shown in the figure. Note that these observations are consistent with the assumption that each particle follows a definite path through one slit or the other slit, and objectively exists as it follows one or the other of these paths. Note also that if we plug up one slit, the corresponding peak disappears. The other peak, however, remains unaffected. The particles, therefore, follow independent paths through one slit or the other.
Figure 3: The double-slit experiment with classical particles results in a two-peak pattern.
Next, imagine we perform a similar experiment (Fig. 4), only instead of sending particles of sand through empty space from the source to the screen, we fill the whole space with some medium, such as water. Instead of a source of sand particles, we use a vibrating object (such as a water bug jumping up and down) that disturbs this medium, continuously generating waves that spread out in all directions.
Figure 4: The double-slit experiment with classical waves results in an interference pattern.
The crests of the waves are shown in the figure as circles with solid lines, while the troughs of the waves are shown as circles with dotted lines. For the screen we can use a long line of small wave detectors (such as floating corks that move up and down when a wave hits them). Note that the waves are not localized in space like particles, but are spread throughout the whole medium. As a result, a wave does not go through just one slit or the other, like a particle, but goes through both slits simultaneously, resulting in an interference pattern. When the crest of one wave combines with the trough of another wave, they cancel each other out, leaving nothing (Fig. 5). This interference phenomenon is an essential feature of waves.
Figure 5: Unlike two particles, two interfering waves can either add up or cancel out.
This interference behavior is very different from the behavior of two particles. And the results of this experiment reflect this difference: the screen (Fig. 4) shows a wave interference pattern, with large wave intensities where the waves from the two slits add up (two intersecting lines of the same type) and small wave intensity where the waves from the two slits cancel out (a solid line intersecting with a dotted line). Note that this complex interference pattern is quite different from the simple pattern we saw with the particles (Fig. 3). With particles, the peaks were clearly independent: one peak from one slit, the other peak from the other slit. With waves, however, the entire interference pattern reflects a coherent effect of both slits, and if one slit is plugged, the whole pattern disappears.
The two experiments above contrast the classical behavior of particles with the classical behavior of waves. When this double-slit experiment is performed on a microscopic scale with small particles, however, we begin to observe a very strange mixture of waves and particles. So, let us conduct another thought experiment with these small particles, or quanta (Fig. 6). Like the first experiment, we have a source of particles traveling through empty space. Only this time, we use electrons as the particles, and make the slits so small and so close together that you need a microscope to see them. We then observe that the source emits the electron particles in chunks, and that the screen detects the electrons in chunks, just as before. The pattern we see on the screen, however, is not the two-cluster pattern we saw for classical particles. Instead, we see the interference pattern for waves!
Because the electron produces the interference pattern that is the signature of waves, it cannot be a particle. But the electron cannot be a wave either, since it arrives at the screen in discrete chunks, which is the mark of a localized particle. Our observations thus suggest that the electrons are localized particles when they leave the source and when they arrive at the screen, but that the electrons are waves everywhere in between. This is very odd, indeed, for it seems to imply that the localized particle at the source dissolves, in some sense, into a non-localized wave that propagates through space from the source to the screen, where it transforms back into a localized particle again!
Figure 6: The double-slit experiment with very small particles results in a wave-like interference pattern.
This experimental evidence flies in the face of materialism. According to materialism, any particle always has an objective existence at a specific location in space. In particular, according to materialism, the electron must follow a single path through one slit or the other, and cannot travel through both slits like a non-localized wave. That, however, is exactly what the electron evidently does.
Let's test this hypothesis that the electron propagates as a non-local wave by performing another thought experiment. Suppose that we look closely at each of the slits (with two narrow laser beams, for example) while the electrons are supposed to be passing through (Fig. 6). Will we see a localized particle passing through one of the slits, or will we see some kind of wave passing through both slits at the same time? Surprisingly, when we actually perform this experiment, we do see a localized particle go through just one of the slits, just as a materialist would expect. In addition, however, we no longer see the interference pattern of waves on the screen. Instead, we now see the regular two-peak pattern for particles, like the pattern shown in figure 3. Thus, our observation somehow changes the behavior of the electrons from waves to particles. Indeed, as soon as we turn off our laser beams, the interference pattern immediately reappears on the screen. So the only way to see the wave pattern is to refrain from observing which slit the electron goes through; and when we observe its path through one slit or the other, we do not see the wave pattern anymore. Therefore, when we do not look at it, the electron is a non-local wave, without any definite localized position. Only when we observe the electron does it have a definite position.
It is important to emphasize the difference between saying that the electron does not have a definite position unless we observe it, and saying that the electron has a definite position but we just do not know what it is. If the electron really had a definite position all the time, then the electron would have to go through one slit or the other, and could never produce an interference pattern. But the electron does produce an interference pattern, so the electron must, in some sense, go through both slits, like a non-local wave. It cannot, therefore, have a definite position all the time. As the Zen master Sengtsan might say, the electron is empty of any independently existing position. Its position exists only in dependence upon its observation. While the electron is unobserved, therefore, its existence is not like that of an ordinary object which we think of as having a definite and objective position in space. Rather, it exists as a non-local wave, with no definite or objective position in the ordinary sense.
Moreover, this non-local wave is not actually a physical wave, like a wave in a physical medium such as water. Rather, the electron's wave is a wave of probability. Where the probability wave has a large intensity, the electron has a high probability of being observed; where the wave has a small intensity, the electron has a low probability of being observed. When it is not observed, therefore, the electron exists as a wave of probability that represents a potential position, not an actual position. In addition, this probability wave does not exist in the ordinary three-dimensional space of our physical world. Rather, it exists in an abstract infinite-dimensional space described by complex numbers (i.e., numbers that involve the quantity i, which has the unusual property that i2 = -1). Whatever we might try to say about the nature of an unobserved electron, one thing is for certain: it cannot be understood as having any conventional kind of existence that can be described with simple physical or mathematical concepts. As Heisenberg explains,
If one wants to give an accurate description of the elementary particle—and here the emphasis is on the word "accurate"—the only thing which can be written down as description is a probability function. But then one sees that not even the quality of being...belongs to what is described.8
These remarkable conclusions about the nature of elementary particles generalize to all forms of matter and energy. We can perform all the above experiments with any subatomic particle. The results will be the same. Moreover, the position of a particle is not its only attribute that is empty of inherent existence. The particle's velocity, for example, is also empty of objective existence independent of observation. Only in relation to an observation does a subatomic particle have a definite attribute of position or velocity. The same conclusions apply to collections of subatomic particles, such as atoms and small molecules. Indeed, because quantum mechanics describes all matter and energy, we can generalize these conclusions to the entire physical world of objects. When millions and millions of atoms are clumped together into a speck of sand or some larger object, however, the strange interference effects are not usually noticeable. This does not mean, however, that the weird quantum reality is not there anymore. It just means that it is not noticeable anymore. The situation is analogous to the fact that the curvature of the earth is not noticeable in a small area of land. That we cannot observe the curvature in such a small area, however, does not mean that the earth has actually lost its roundness. As Heisenberg said,
The statistical features of natural laws are ubiquitous and a matter of principle. It's just that these quantum-mechanical features are far moreobvious in atomic structures than in the objects of daily experience.9
So all matter is really this way. Even large objects of our ordinary experience do not have objectively existing properties unless and until they are observed. This is very startling. Or it shouldbe very startling! As Niels Bohr once said,
Those who are not shocked when they first come across quantum theory cannot possibly have understood it.10
The physical reason the quantum nature of most objects is not noticeable is because of a phenomenon called decoherence. When one wave passes through two slits, the resulting two waves are coherently related to each other, resulting in the interference pattern. When millions and millions of particles are gathered together, though, there are so many of these waves interfering in so many ways that they appear on the macroscopic scale to average out, or decohere. This is analogous to how the curvature of the earth appears to disappear in a small area of land. The decoherence effect is the reason we can normally neglect the quantum nature of macroscopic objects, and treat them as if they had objective existence. Similarly, we can normally neglect the curvature of the earth, and treat it as if it were really flat.
It is important to remember that this decoherence effect does not change the underlying quantum reality. The quantum coherence is really still there—it is just hidden in the microscopic details and not noticeable on the macroscopic scale. Thus, because of this decoherence effect, the macroscopic world usually appears in a manner that is consistent with the materialistic idea of objectively existing matter. Despite appearances, however, objects never depart from their true quantum nature, they never actually become the objectively existing objects that they appear to be, any more than the earth actually becomes flat even though it might appear that way. The apparent observation of an electron's actual position, in other words, results from our ignorance of its quantum coherence. When the quantum coherence is ignored, the electron appears as if it had an actual position. In reality, however, the electron does not have any actual position, just as the earth does not have any actual flatness when we ignore its curvature. We can only imagine that the position actually exists by ignoring the quantum coherence.
Thus, according to quantum physics, the attributes of physical objects are only imagined by us to have definite or actual existence. Or, as Sengtsan might say, they are empty of such existence. Just as the earth always is round, but appears with greater or lesser degrees of curvature, these objects always exist in a state of quantum coherence, appearing with greater or lesser degrees of decoherence. The electron in our double-slit experiment, for example, is very coherent when it remains unobserved. Thus, it does not have a definite position at one slit or the other. But when the electron's position is measured at one of the slits, its coherence becomes so difficult to detect that we can imagine the electron to have a definite position. Thus, in one sense, it appears as though we can precisely measure a position of the electron. Yet, in another sense, such a position never really can be shown to have definite existence.
This testimony of modern physics has striking resemblance to the testimony of the mystics. Consider, for example, the words of the Buddha:
I teach the non-existence of things because they carry no signs of inherent self-nature. It is true that in one sense they are seen and discriminated by the senses as individualized objects; but in another sense, because of the absence of any characteristic marks of self-nature, they are not seen but are only imagined. In one sense they are graspable, but in another sense, they are not graspable.11
Remarkably, both physics and mysticism teach us that the appearance of an objectively existing world independent of observation is an illusion. Moreover, they both say that even the observed world does not exist objectively with anything like the definiteness that we imagine. And this illusion of definite objective existence, they tell us, arises from our ignorance of the true nature of phenomena. Far from being incompatible with the testimony of the mystics, therefore, modern science seems to make many of the same claims as the great mystical traditions about the nature of phenomena.
Although modern physics is quite compatible with mysticism, this does not imply that the evidence of physics proves or validates the claims of mystics. While their claims converge, the type of experience used by physicists and mystics to validate claims are significantly different. Whereas physics is fundamentally extrospective, mysticism is radically introspective—to the point of transcending the subject-object distinction altogether. The mystic's non-dualistic Knowledge or Gnosis far transcends any knowledge derived from physics. Gnosis does not, and cannot, be demonstrated or proved using physics. Nevertheless, an understanding of the compatibility between modern physics and mysticism can provide the valuable service of helping to dispel the illusion of materialism, and reveal the Gnosis that is already our true nature. For, just as we falsely imagine the electron to have an actual position by ignoring its true nature, so we falsely imagine that we have actual ignorance by ignoring our true nature. So, by recognizing that our own ignorance is itself falsely imagined to be real, our true nature is clearly revealed.
- Thomas J. McFarlane, Center Voice: Summer-Fall 1999,
Tom McFarlane has a B. S. in physics from Stanford University, an M. S. in mathematics from the University of Washington, and is now in the graduate program in philosophy and religion at the California Institute for Integral Studies in San Francisco. One of Joel's first students when the Center was founded in 1987, Tom attended for several years thereafter. Although he has since moved away from Oregon, he continues to attend Center retreats at Cloud Mountain and is one of the sponsors of Joel's annual seminars in the Bay Area. Tom also maintains the Center's web site.
1. Niels Bohr, The Philosophical Writings of Niels Bohr, Vol. I, (Woodbridge, Connecticut: Ox Bow, 1987), p.54.
2. Challenge and Response, (Eugene, Oregon: The Center for Sacred Sciences, 1992), p. 10.
3. Sengtsan, hsin shin ming: verses on the faith-mind, tr. Richard B. Clarke (Buffalo, New York: White Pine Press, 1984).
4. Werner Heisenberg, Physics and Philosophy, (New York: Harper and Row, 1962), p.145.
5. Dwight Goddard, ed. A Buddhist Bible, (Boston: Beacon Press, 1970), p. 313.
6. Heisenberg, p. 201.
7. Bohr, p. 1.
8. Heisenberg, p.70.
9. Werner Heisenberg, Physics and Beyond, (New York: Harper and Row, 1971), p.95.
10. Niels Bohr, as quoted in Heisenberg, Physics and Beyond, p. 206.
11. Goddard, p. 297.