||Our Time: 2. Quantum Theory and Reality|
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2001, 2004, 2010
copyright Ronald C. Pine
One ought to be ashamed to make use of the wonders of science embodied in a radio set, while appreciating them as little as a cow appreciates the botanical marvels in the plant she munches. Albert Einstein
The twentieth century is a remarkable story of technological achievement. Within a short period of historical time electricity, radio, TV, fiber optics, computers, and the Internet and the Web, have all become an every day facet of our lives. I take for granted that I can turn on a TV set in Hawaii and receive, almost instantaneously, a program that originated in Atlanta or New York. Or turn on my computer and receive e-mail and surf web sites from around the world. Only a short time ago exchanging information between New York and Hawaii required the same time it takes to send a spacecraft to Mars today. Except for power failures, few people in the developed world know what it was like for most of the human species every night, throughout 99 percent of our history, to face the silent darkness of space and its sea of stars alone without the reassuring lights of civilization. We live in a special time. Never before has such intense, radical technological change taken place. In this chapter we will see that there has been another radical change: Something very strange was discovered about reality along the way.
In a popular TV show in the 1980s the scientist Carl Sagan sits in the elegant dining room of Cambridge University waiting to be served an apple pie. He tells his audience, "If you wish to make an apple pie from scratch, you must first invent the universe." He begins to tell the modern scientific story of physical matter, our view of physical objects such as apple pies, tables, rocks, trees, birds, and even people. He notes how modern science stretches our imagination to the limit in portraying the dimensions of atoms and the large numbers routinely used by science. (Remember about 10 billion atoms can fit within a single printed letter on this page.) Sagan explains that almost every part of ourselves and the physical matter on Earth were formed billions of years ago in the ferocious interior of gigantic stars. "The calcium in our bones, the iron in our blood, the gold in our teeth, the complex molecules in our apple pies, all came from the stars. . . . We are made of star stuff."He continues with the discovery that everything consists of molecules and these in turn are hooked-together atoms, which are made of subatomic particles and mostly empty space. He characterizes a typical atom as having "a kind of cloud" of electrons on the outside, "clouds of moving fluff."
|What is an Electron? Of Particles and Waves|
O amazement of things -- even the least particle! Walt Whitman
Our story will be begin here because it is the electron, and our knowledge of it, that has been responsible for so much of the technology that we take for granted today. Without the electron there would be no electricity, no electric lights, no TV, radio, CDs, DVD's, thumb drives, cell phones, computers and electronic social networking. We would not have supermarket doors that open automatically or computers to play video games, surf the Web, and do word processing and spreadsheets for business. But what exactly is an electron? In the early moments of the twentieth century scientists found themselves asking this very question. The discovery of radiation and the atom promised to open up a strange new world of knowledge, understanding, and power.
At first physicists assumed that the atom was like a miniature solar system. At the center was a nucleus consisting of particles glued together somehow, and that circling this nucleus were the swiftly moving electrons, like little particle planets. This model did not last very long. Although we still use a version of this model today to have some visual handle on what the atom looks like, the pioneers of atomic physics discovered fairly quickly that mathematical calculations based on this model predicted that the electron would crash into the nucleus in an instant.
Physicists also discovered that electrons could be stripped from the atoms and made into beams of radiation. This was a great breakthrough, because they could manipulate these beams, and begin to deduce from the behavior of these beams the nature of the electron itself. A similar channel of investigation was taking place in attempting to understand the nature of light. From this another remarkable discovery was made: Beams of electrons behaved very much like beams of light.
There is one simplification at least. Electrons behave in this respect in exactly the same way as photons; they are both screwy, but in exactly the same way. Richard Feynman
We saw in Chapter 7 that the speed of light was considered a paradox by many at the turn of the century. By this time the nature of light was also very controversial and something of a paradox. Under some conditions light seemed to behave as if it consisted of very small particles of matter (now called photons). Under other conditions, however, light showed clear signs of being a wave of energy, a disturbance of a medium, the intensity of which could be measured. To understand how this is a problem, we must first clearly understand that a particle and a wave are very different phenomena.
A particle is a localized piece of matter, like a baseball, that at any given time has a definite size. It can be in only one place at a time. A baseball thrown in Hawaii cannot be in New York at the same time. Furthermore, we assume, ontologically speaking, that we may discover in this marvelous universe some very strange objects but that, regardless of how strange they are, if they are objects, then they will have a definite location at any given definite time.
A wave, on the other hand, is a very different kind of thing. In fact it is appropriate not to refer to it as a thing at all, but rather as an event or phenomenon. Things by definition have a definite localized size at a given definite time. Waves do not. Imagine dropping a pebble into a still pond of water. At first there is a small splash, and then circular waves move away from the spot where we dropped the pebble. The wave spreads out; it does not stay in one place, but can be in many places at the same time. Also, it is the medium of the water that transmits the energy of the dropped pebble. The wave is simply a disturbance of the medium. It does not have an existence of its own like the smile of the Cheshire cat in Alice in Wonderland. Without the water being in the pond there would be no waves.
On the north shore of the Island of Oahu in the State of Hawaii, every winter large waves pound the shoreline. These waves are caused by the seasonal winter storms migrating northeast of the state in the jet stream on their way to make life miserable for people in the Pacific Northwest, and eventually much of the rest of the continental United States. The winds from the migrating storms cause a significant disturbance in the sea and a series of undulations are transmitted many miles until finally, reaching the reef on the north shore of Oahu, spectacular waves of thirty feet or higher break and push forward a mountain of water and foam toward the beach. On the cliffs overlooking Waimea Bay you can watch a gigantic half circle of water march relentlessly toward the beach and then simultaneously, across a quarter mile area, surge onto the beach. It is a very spectacular sight. Tourists travel many thousands of miles to see it, and single-intentioned surfers wait in anticipation all year, hoping to be the first to ride the biggest wave on record and survive.
|It would be a strange event indeed, if one day while watching wave after wave break, we saw one wave flow in its normal way toward the beach, and then, just as the wave was about to touch the fringes of the vulnerable beach, the entire half circle of water collapsed instantly to a single unpredictable point on the beach and exploded! The wave would have turned into a massive particle located at one place, rather than spread out as waves normally are. Imagine wave after wave doing this, with the location of the collapse being unpredictable each time. Strange indeed this would be, but something like this is what electrons and photons seem to do!|
All of modern physics is governed by that magnificent and thoroughly confusing discipline called quantum mechanics .... It has survived all tests and there is no reason to believe that there is any flaw in it .... we all know how to use it and how to apply it to problems; and so we have learned to live with the fact that nobody can understand it.
The science of the subatomic realm is called quantum physics or quantum mechanics. The word "quantum" refers to the fact that energy at the subatomic realm comes in packets, or quanta; energy is said to be "discrete" rather than continuous. The best way of understanding the implications of discrete motion is to understand the most famous phrase in this science, the "quantum jump." As we will see, this does not refer to a continuous quick motion, such as a child jumping from one place to another, but rather a discontinuous, instantaneous movement from one place to another. In other words, quantum objects seem to be able to move from place to place without being anywhere in between. They seem to "pop" in and out of existence.
In the following pages we are going to retrace the same baffling steps taken by physicists in the twentieth century. The goal was simply to understand the nature of subatomic objects such as the electron and the photon. The result was a revolution in thought so radical that even Einstein could not accept it. We will be using though a method Einstein would have approved of, what are called "thought" experiments. Instead of looking at the actual technical experiments, we will imagine a series of composite pictures that remain true to the actual experimental findings.(1)
Imagine first a lead box impenetrable except for two microscopic slits on one side. Inside the box the side opposite the slits is coated with photographic film. Imagine that on the outside facing the two slits we have a source of radiation, beams of electrons or light, and that we aim this radiation at the face of the box with the two slits. By looking at the kind of exposure that results on the photographic film, we can infer what kind of radiation is penetrating the box. For instance, if the radiation consists of beams of particles, then only those particles that happen to be aligned with the two slits will pass through into the box, and the result should be a "particle effect": The photographic film should show a diffused piling up of little hits adjacent to the two slits.
On the other hand, if the radiation is a wave, then a much different effect should result. We should see a "wave effect," roughly the same result we would see if we dropped two stones into a still pond of water at the same time. Two circular undulations would collide into each other and interfere with each other. In our example, a wave would split in two as it enters the two slits, and then the two waves would begin to spread out again, eventually colliding with each other as in our pond example. This should cause an "interference effect," a wave picture, on the photographic film. Instead of a piling effect adjacent to the two slits, the radiation would spread throughout the length of the photographic film, producing alternating bands of exposure. Some of the wave crests would meet and accentuate each other, and some would meet the troughs of other waves and cancel each other. This is similar to a wave approaching the beach and a backwash wave meeting it and producing a bigger wave, or a crest meeting a trough of another wave and canceling each other. The exposed bands on the photographic film would be the result of the crests meeting. Such a resourceful experimental process is what Einstein had in mind with his clock analogy discussed in Chapter 7. We may not be able to see the invisible electron, but we can infer a reasonable representation of what it is by observing the effects it has on macroscopic objects.
When similar experiments are done, the result is remarkable. The photographic film always shows an interference effect indicating a wave (see Figure 8-1a). Amazingly, the radiation produces this same effect in passing through a vacuum, presumably a physical state with no wave medium such as air or water. How can a wave exist without a substance of some sort to disturb? Also, when we look closely at the exposure of the film, the exposed areas show piles of little hits, as if millions of individual particles hit the film, each blackening only a single grain of film in unpredictable locations (see Figure 8-1d). Remember that if the radiation is a wave, then as it reaches the film, it should be spread out along the entire length of the film like a wave breaking on a beach. But how can it hit at only one unpredictable place? This is as ridiculous as the possibility of watching a wave march toward a beach and seeing the entire wave collapse at a single point on the beach!
In the universe great acts are made up of small deeds. Lao Tsu
Obviously, more experiments are necessary. Baffling results are common in science. So let's close one of the slits and see what happens. Perhaps the particles are so small that as they penetrate the slits they ricochet all over the interior of the chamber, bouncing off each other in a wild unpredictable manner which eventually somehow produces the illusion of an interference effect. After all, the electron is about 10,000 times smaller in mass than an average atom. Thus, in closing one of the slits, we would lessen this wild ricocheting, and a piling effect should result adjacent to the single slit.
Sometimes nature cooperates. If we alternate in opening and closing each slit, the result appears consistent with the particle hypothesis -- a double piling effect adjacent to each slit (Figure 8-1b).
But wait. To be sure that we are dealing with a particle, let's return to our original experimental setup with two slits open simultaneously. This time, however, we will lower the intensity of the radiation. Another way to lessen the possibility of the ricochetting effect, and at the same time rule out once and for all the wave hypothesis, is to filter the radiation to such a point that only a single measure of radiation passes through into the chamber at a time. If the radiation consists of particles, if only a single particle is passing through at a time, it can go through only one slit or the other. If it is a particle, then it cannot ricochet off other particles or be in two places at the same time and ricochet off itself.
The "paradox" is only a conflict between reality and your feeling of what reality "ought to be." Richard Feynman
Conducting this experiment will take more time for an exposure to develop because millions of particle hits will be required to make an exposure, and there are three possible paths for each particle: to penetrate the chamber through either of the two slits or be stopped by the lead barrier. Nevertheless, we should eventually observe a particle effect -- a double piling effect of hits adjacent to the two slits (Figure 8-1b).
Alas, nature fails to cooperate. The result is an interference effect, exactly as in our first case (Figure 8-1a and 8-1d)! Now we are really in trouble. Why should we get a wave effect with two slits open, even though the exposure is the result of cumulative unpredictable hits, and a particle effect with only one slit open? With two slits open the radiation is acting as if it penetrates the chamber at two places simultaneously, something only a wave can do. With one slit, however, the radiation is more localized,(2) as we would expect from particles that can be in only one place at a time.
It is easy to lose sight of the philosophical significance of these results. Many of the great names of science, however, who were working at understanding this baffling microscopic realm, also had a background in philosophy, and it was immediately apparent that there was something major at stake here. Since the time of the ancient Greeks and the fledgling beginnings of scientific exploration, we have assumed that we are dealing with one world, one consistent reality. That is, even though we expect the world to be baffling at times, with strange and new details of discoveries, we also expect that whatever these details are, they stay the same independent of our knowing. They are objectively "out there" waiting for us to discover, and they are what they are regardless of our knowledge or ignorance. We assume as Newton did that the world does not depend on us or how we choose to make our observations of it. We do not expect something to be a particle on Mondays, Wednesdays, Fridays, and Sundays, and a wave on Tuesdays, Thursdays, and Saturdays -- especially when these phenomena are of entirely different types. What kind of a world would it be for us if dogs were dogs on certain days of the week but turned into cats on others?
If we take quantum theory seriously as a picture of what's really going on, each measurement does more than disturb: it profoundly reshapes the very fabric of reality. Nick Herbert
Let's try one more example. What we want to know is, does the radiation pass through both open slits simultaneously or only one? Consider then the following experimental arrangement: both slits open, one measure of radiation entering the chamber at a time, but with one added feature -- a detection device inside the chamber that will reveal whether or not the radiation is passing through both slits as a wave would or only one or the other of the slits as a particle would (Figure 8-1c). Because the situation is almost identical to the case in which an interference effect was recorded, we would expect to see the detection device react as if a wave was surging through both openings simultaneously. On the other hand, if the radiation consists of particles, then only one instance of detection should be recorded at a time. Remarkably, the latter is the case -- only one instance of detection is recorded at a time -- and the photographic result is now consistent with the arrangement with only one slit or the other open (Fig. 8-1b)!
As physicists conducted further experiments with subatomic phenomena, they found that all subatomic phenomena display this same ambiguity. This ambiguity has come to be known as wave-particle duality. This result was not easy to accept. One of the most fundamental principles of science seemed to be mocked by these results: the notion that we are dealing with, and can know the details of, an objective world. To use Einstein's cosmic clock analogy, we expect that the internal mechanism stays the same regardless of our hypotheses and beliefs about what the internal mechanism is. We do not expect the internal mechanism to change as we change our experimental attempts to know the internal mechanism.
It is perhaps one of the greatest achievements of the twentieth century that in spite of this shock, a very successful mathematics was developed that not only allowed physicists to predict the results of the above experiments but also produced one of the greatest scientific and technological success stories in recorded history. In 1926 the physicist Erwin Schrodinger discovered a wave equation that predicts the above results, but with a high epistemological and ontological price.
As we would expect from the name, the equation literally portrays the radiation as a wave, but a very strange wave. According to the equation, in our two-slits-open configuration as soon as the radiation leaves its preparation point, it begins to spread out in a strange multidimensional "hyperspace." As it encounters the slits it splits, as any real wave would, passing through into the chamber and interfering with itself. As the radiation touches the photographic film, however, all of the energy of the wave collapses to a single unpredictable point! We can never predict at what exact point the radiation will be received, but we can always, with a remarkable consistency, predict the probability of where it will strike and the overall statistical pattern, not only for this particular arrangement, but for all the others as well.
Because of the influence of the twentieth century philosophy called logical positivism, most physicists have been taught to think of the equation as a calculation device, not as depicting what is literally real. The special mathematical function used is thought to represent only a "probability function" for, given initial conditions, the probability of finding a hit, or a pattern of hits, at a particular location. Thus, the only waves that exist are said to be "probability waves." Thus, just as some astronomers during the middle ages thought of Ptolemy's epicycle as just a device used for making predictions where planets would be, the wave equation is just a device for predicting what electrons will do. For the logical positivists, the question of reality was a nonsolvable useless philosophical question.
We have sought for firm ground and found none. The deeper we penetrate, the more restless becomes the universe; all is rushing about and vibrating in a wild dance. Max Born
But wait. Given the tremendous success of our electronic technology in the twentieth century are we really no longer interested in the foundational reality behind all this success? Don't we still want to know what electrons and photons are? Let's look at one more example.
In Figure 8-2a imagine a light source directed at a half-silvered mirror, a mirror covered with a very light reflective coating. Such a mirror functions as a beam-splitter. Shining light on the mirror tilted at an angle will cause the light to split into two separate beams. If we assume that light consists of little particles called photons, then the physical properties of the half-silvered mirror should cause each individual photon to pass through the mirror or be reflected at an angle. Each photon must become part of one beam or the other. If we set up photon detectors at the appropriate angles, at points A and B, individual detections at A or B should result. With this experimental arrangement, the mathematics predicts that over a sufficient period of time 50 percent of the light will be received at A and 50 percent will be received at B. Furthermore, if the intensity is lowered through filtering, such that only a single photon approaches the mirror at a time, then only a single whole photon should be detected at a time. Detections at A and B should never be recorded simultaneously. This prediction is just common sense. If the photon is an individual object, it cannot be in two places at the same time.
When such an experiment is
actually conducted one whole unit of energy is detected at
either A or B, confirming the particle interpretation of
subatomic phenomena. If a photon is a particle, it will
pass through the mirror and be detected at A or be
reflected and detected at B. However, remember that the
Schrodinger equation is a wave equation. If the equation
is interpreted literally, the equation describes that the
light energy is in both channels! The half-silvered mirror
splits a wave packet into two "hyperspatial, virtual/real,
probability" waves. Then at the exact moment that the
energy reaches the detectors, some sort of strange
decision is made, and the entire unit of energy is
received at only one point, at either A or B! The wave
packet "collapses." If a whole unit is received at A, then
the energy that was approaching B has jumped over
to A. In addition, the equation predicts this will happen
even if the two detectors are separated by many light
years, and even if one detector is much closer to the half
silvered mirror than the other. The latter case implies
that the energy that is approaching the one that is
closer, say B, waits?! until the energy approaches A, and
then either jumps to A or the energy that was approaching
A goes "backward in time" and collapses at B. The
mathematics always works, but what it describes literally
seems impossible. Like Alice in Wonderland, we cannot
believe in impossible things can we? According to the
mathematics, there is an instantaneous collapse of
potentiality in multidimensional hyperspace to a
three-dimensional location. Strange indeed. So physicists
who follow the logical positivists party line tell us that
we must not think of the split wave packets as real, but
only as a description of the probability of where photons
But wait. Can we prove that the light really passes through both channels? Quantum jumping and wave collapsing aside, we can at least test for the photons passing through both channels. Consider the following arrangement (Figure 8-2b). This time we will create an interferometer by placing totally reflecting mirrors at the points where detectors A and B were. Thus, if the light beam is really split by the half-silvered mirror, the totally reflecting mirrors will now reflect the split beams of light. If we aim these totally reflecting mirrors so that the beams will meet again, it is possible to take a picture of the waves interfering with each other, just as we did in the two slit experiment. With this arrangement, interference fringes result similar to that found in the two slit experiment. The interference effect can be produced by having one of the totally reflecting mirrors slightly farther away than the other, so that the light waves will arrive out of phase. The beams are recombined by another half-silvered mirror and transmitted to a chamber with a photographic plate.
If the intensity of the light is reduced to one photon at a time, the interference effect can only be accounted for by assuming the photon really splits into two wave packets and then recombines. In fact, if we pick up an ordinary playing card and block one of the paths, there is no interference picture. Instead, a defused piling exposure is created, similar to the particle picture we received when only one slit was open in the previous experiment. If the energy is a wave, then we can understand the interference picture. If the energy is a particle, then we can understand the fact that only one detector at a time receives one whole unit of energy. The result of one arrangement indicates that a wave of some kind is really passing through both channels simultaneously. The result of the other makes sense, if we assume that the energy is passing through only one channel at a time. If the energy is passing through both channels at the same time, why do the detectors not trigger simultaneously? How does the energy passing through one channel get over to the other detector? How could this possibly happen if the detectors are far enough away that any transmission of a signal between them would require a speed greater than the speed of light? It is time for a little philosophy.
|The Copenhagen Interpretation|
In a sense [for the Copenhagen Interpretation], the observer picks what happens. One of the unsolved questions is whether the observer's mind or will somehow determines the choice, or whether it is simply a case of sticking in a thumb and pulling out a plum at random. Dietrick E. Thomsen
Atoms are not things. Werner Heisenberg
Nature at the subatomic level apparently does not conform to normal logic. Since the time of the ancient Greeks, Western logic, through Aristotle's law of excluded middle, has demanded an "either-or" in our relationship with the universe. Either light is a particle or it is not a particle. Either light is a wave or it is not a wave. Either the light splits and goes through both channels or it does not. If it goes through both channels, it should be detected at both channels. It is not detected at both channels, yet it does go through both channels. If it goes through both channels, why is one whole unit of energy detected at only one detector? How do two halves spatially separated become one whole unit instantaneously?
No logical inconsistency exits within the mathematics itself. In the particle-effect case, the mathematics allows us to predict that approximately 50 percent of the time detector A will record a unit of energy and 50 percent of the time detector B will record a unit of energy. In the interferometer arrangement, the mathematics predicts an interference effect, and even allows a straightforward calculation of the wave length of light by measuring the interference fringes. The problem is more in our reaction to the results of these experiments and the success of the mathematics. We want to know what kind of a thing is producing these strange results. What is going on "out there" that enables the mathematics to be successful? Our minds desire a complete understanding. What is real? What is the truth?
These questions reflect our natural curiosity about reality. We want to go deeper, to find the basic, hidden causes of all things. Western science since the ancient Greeks has assumed an ontology: The cosmos consists of one distinct, complete reality full of individual separated details. We have also assumed an epistemology: The details, whatever they might be, can be known, and the process of knowing these details does not affect what the details actually are independent of the knower. This is consistent with our common sense and what each of us experiences everyday: a world undisturbed by human thoughts, wishes and desires, full of things, spatially separated from each other, and interacting with each other through distinct recognizable forces. If someone has a tangerine tree in his yard, he might wish that it would be an apple tree, but it will still be a tangerine tree. Similarly, we do not think of someone thinking cancer into existence or wishing it away. We think of the cancer being objectively "out there," something beyond our mental control, like trees. We can cut down trees and operate on cancer, but they are distinct realities that we discover with our thinking, not something that we create with our thinking.
Causality may be considered as a mode of perception by which we reduce our sense impressions to order. Niels Bohr
When Einstein has criticized quantum theory he has done so from the basis of dogmatic realism. Werner Heisenberg
So it is natural for us to think of electrons or photons as some sort of independent things. They show signs of being particles, so we begin to think of them as if they really are particles independent of our observations of them. But they also shows signs of being waves, and they cannot be both waves and particles at the same time, no more than a tree can be both a tangerine and apple tree at the same time or someone can have cancer and not have cancer at the same time.
In the 1920s a few philosophically minded physicists, led by the Nobel Prize-winning physicist Niels Bohr, realized that nature was trying to tell us something very important. Once again nature was using paradox to alert us to a fundamental error in the assumptions we were making and the way we were asking our questions. According to Bohr, and what is known as the Copenhagen interpretation,(3) the results of these encounters with subatomic phenomena amount to a major epistemological discovery. Descriptive terms such as "particle," "wave," "position," "mass," and "spin," are human concepts. These concepts involving assumptions of space and time work for us at a normal macroscopic level and will always be indispensable for describing the results of our physical experiments. But nature is now making it very clear to us that we have reached a barrier in our attempt to describe it fully in terms of human concepts derived from ordinary experience.
Wave-particle duality is nature's way of informing us that cannot impose our human concepts on the subatomic level. Just as Einstein had discovered that we cannot impose our normal assumptions of space and time to all levels of reality, so quantum physics reveals that we have no empirical justification to impose our most basic thoughts about the nature of reality on the subatomic realm. The idea of an extended thing sitting in a three-dimensional space, waiting for us to discover it, is revealed as another human projection, a limited image of reality, more of an echo of the way our minds work than reality itself. According to Bohr, nature empirically reveals this understanding to us by showing that we can have only complementary views of reality. If we set up an experimental arrangement that allows for a wave manifestation of subatomic phenomena, wave effects will be observed. If we set up an experimental arrangement to view subatomic phenomena as particles, particle effects will be observed. According to Werner Heisenberg, another major contributor to the Copenhagen interpretation, what we observe in our experiments is not nature itself, but nature exposed to our methods of questioning nature. In short, an electron is not a thing until we observe it!
Bohr argued that this interpretation is a necessary, "pragmatic" response. Experiments must be conducted in human terms, in laboratories full of macroscopic equipment in three dimensions. Our laboratory equipment must be capable of measurements that are understandable through the conceptual reference frame of human beings. This barrier, however, should not be seen as an end to science or as an imposed state of ignorance. It is a discovery, a momentous discovery about ourselves and the nature of science. To discover that complementary views of reality exist, rather than only one unified view, is as important as Einstein's discovery that the reference frame of an observer is crucial for measuring space and time. Rather than limiting science, Bohr viewed this new knowledge as liberating the sciences from the tyranny of thinking that each science must explain itself in terms of a more basic science such as physics and chemistry. Biology, for instance, could very well be a complementary perspective on living things, not totally reducible to physics and chemistry.
|A Debate: Bohr and Einstein|
We believe in the possibility of a theory which is able to give a complete description of reality, the laws of which establish relations between the things themselves and not merely between their probabilities .... God does not play dice. Albert Einstein
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. Niels Bohr
Ironically, the main resistance to the Copenhagen interpretation came from Albert Einstein and a few of his followers. Einstein objected very much to the idea that we had stumbled upon a barrier to knowing what is real. Philosophically, Einstein was a realist who believed that the goal of science was to conjecture boldly about the nature of reality from the details of our empirical observations. He acknowledged that as we continued to probe nature for her secrets, we would encounter more and more exotic features, the majority of which would never be directly observable because of human limitations. He believed, however, that the human mind could always infer at least the most likely hypothesis about the nature of the reality causing the events we do observe. Thus, although Einstein introduced the world to a revolutionary view of space and time, one that destroyed the classical or Newtonian conceptions of absolute space and time, he nevertheless remained a classical physicist faithful to the concept of reality Descartes stated centuries earlier: "There is nothing so far removed from us to be beyond our reach or so hidden that we cannot discover it."
As we noted previously, for Einstein, nature was like a mysterious clock. We are limited to observing only the exterior features of this clock. We may never be able to see directly inside and know for certain how the clock works, but by observing and thinking about the movement of the hands long enough, the human mind will provide a very likely answer as to how the clock works. For Einstein a clockwork for the universe exists and can be known. For Bohr, for us to assume that a clockwork exists independent of our observations that we can picture in human terms is only another human philosophical bias, another example in a long line of assumptions that experience validates at a certain level, but which experience at another level now demonstrates cannot be considered to be true.
Although Bohr thought quantum physics to be in part an important epistemological discovery, and the barrier between the human mind and reality primarily pragmatic, the Copenhagen interpretation does raise the question of whether this epistemological discovery is also an ontological one. For Einstein, Bohr's interpretation was much too close to, and in fact seemed to imply, a traditional ontology -- an ontology historically very much opposed to the major goal of scientific method. If an electron is not a thing until it is observed by some instrument, does this not imply that reality depends on our observations, and hence, ultimately the thoughts we use to frame the world? Does this not imply that reality is created by human thoughts?
Metaphysical Idealism is a old and widespread belief stating that the physical world as we experience it is basically an illusion; the perception of a world of material things separated in space is said to be only an appearance. Individual things exist only in so far as we have an idea of them. Supporters of this metaphysics argue that if there were no human observer or recording instrument of any kind in a forest, then a falling tree would make no sound. In fact, there would be no trees to fall and no forest. When I walk out of a room, I assume that the physical room and all its contents are still objectively there. But according to the Idealist, the room ceases to exist if there is no one there to have a thought of the room.
| Would it (the world)
otherwise (without consciousness) have remained a play
before empty benches, not existing for anybody, thus
quite properly not existing? Erwin Schrodinger
First they told us the world was flat. Then they told us it was round. Now they are telling us it isn't even there! Irving Oyle
The majority of scientists have always viewed this metaphysics with disdain, as more of a symptom of despair of the sometimes harsh realities of the physical world, as primarily a religious view associated with those who find the physical universe threatening and who desire a more perfect world. Does the Copenhagen interpretation of quantum physics validate this philosophy? How embarrassing for Western science if this is so. Imagine that after thousands of years of struggling to know the details of Democritus' atom, Western science shipwrecks into a religious philosophy it thought it had left behind at a more primitive time!
Thus, Einstein viewed quantum physics to be an incomplete theory. He argued that we simply do not know enough yet. Our knowledge is not complete. Because we cannot produce a consistent picture of subatomic phenomena, we obviously do not know exactly what these things are yet and enough about the mysterious forces governing their motions and manifestations. Einstein summarized his view with the famous statement, "God does not play dice with the universe." In other words, God has created one universe and does not choose to have it manifest itself as full of waves at one moment and as particles at another for no reason.
Bohr and Einstein had several public debates over what was the proper interpretation to give to the results of quantum physics. These were fascinating discussions between two intellectual giants, but little was resolved at the time. The vast majority of physicists heeded Bohr's advice that there was a pragmatic limitation inherent in our measuring devices. Physicists should be interested primarily in being able to predict experimental results and not in the question of what is real. They were persuaded, with the help of a philosophical tradition that began with Hume, that the question of what is real is primarily an unanswerable philosophical question. Physics must concern itself primarily with complex experimental arrangements and the derivation of the complex mathematical formulas needed to predict the "constant conjunctions" of appearances first discussed by Hume. On the other hand, motivated by the goal of finding a hidden reality, physicists have also pursued Einstein's dream of a unified picture of reality, of seeking a theory that enables us to understand at a fundamental level all the forces of nature.
Bohr claimed he was being the better empiricist. He
argued that the results of quantum experiments provide
empirical evidence that nature does not have a hidden true
self that can be pictured with human concepts. It seems so
obvious that nature must have some objective true self.
But it also seemed so obvious that time was absolute.
Einstein provided the means to demonstrate with empirical
evidence that there is no universal, objective, absolute
time, one slice of simultaneity throughout the universe.
Today, to continue to believe that there is an absolute
time is simply metaphysical dogma, given the overwhelming
reliable empirical evidence to the contrary. But Einstein
failed, according to Bohr, to understand that the
empirical evidence also demonstrates that the faith in a
hidden, objective reality is but faith in a dogma.
Bell's theorem is easy to understand but hard to believe. Nick Herbert
No elementary phenomenon is a phenomenon until it is a recorded phenomenon. John Archibald Wheeler
So, is there any way of answering the question whether nature has a hidden objective reality? Following Bohr, experiments have been conducted that are consistent with the view that it does not; that in our relationship with the universe we can have only different pictures of its clockwork -- actually, to be more precise, that a precise clockwork does not exist until we attempt to picture it! For many years following the Bohr-Einstein debates it was thought that the issue between them must forever be relegated to the realm of inconclusive philosophical perspectives. No conceivable experiment was known that could be conducted to disconfirm either one. Bohr could argue that the experimental results are most consistent with his theory of complementarity, but he could not prove that some day we would not discover some bizarre hidden reality that explained how an electron could manifest itself as a wave in one situation and a particle in another. Similarly, the followers of Einstein could argue that if we think, and search, long enough someday we will find this hidden reality. No one knew of an experiment that would decide such an apparent metaphysical issue and eliminate or confirm the possibility of a hidden reality.
In 1964 physicist John Bell discovered that it was theoretically possible to test whether or not quantum physics was a complete theory. By tinkering with the mathematics, he discovered that an experiment could be devised to confirm or disconfirm hidden processes, or "variables" as physicists refer to them.
Before we describe this discovery and its application in crucial experiments, let us review first why quantum measurements are so puzzling. The essence of all the puzzles, according to the physicist-philosopher Henry Stapp, is "How do energy and information get around so fast?" In the interferometer experiment we can demonstrate that a wave is passing through both channels. But when we modify the experiment to detect the radiation in each channel, we detect only one whole unit of energy at a time per channel, implying not only that the radiation consists of particles, and therefore not waves, but also that the radiation is not in both channels. In the particle detection experiment the Schrodinger equation describes a wave splitting process with a "probability" wave in both channels, and then an instantaneous collapse of a potential existence to one localized "actual" spot, to either detector A or B. The Copenhagen interpretation deals with this puzzle by claiming it is inappropriate to think of the radiation as some kind of definite real thing before we measure it. The radiation "becomes" something definite, conceptualizable by human beings, only after we measure it. (It is always a particle after we measure it, even though some measurements suggest the particle had wave-like properties between measurements.) Reality, specific attributes possessed by things, according to the Copenhagen interpretation, can only be discussed in terms of an "entire experimental arrangement."
According to Bohr, the problem of quantum measurement can be interpreted as a pragmatic epistemological discovery and does not necessarily imply an idealist metaphysics. Concepts such as "particle" and "wave" are human concepts, and we have discovered that nature will not allow us to picture it consistently with these concepts. Insofar as we must always conduct our experiments through a human framework, with human concepts, there is an epistemological barrier that no future scientific discovery will change. For Bohr, the success of quantum theory represents a "treasure chest" of scientific and philosophical discoveries. The Copenhagen interpretation should not be viewed as advocating a dogmatic end to research and discovery, but rather a dramatic discovery that continues a trend first started by Copernicus and sustained by the startling discoveries of Einstein: The universe is not required to conform to human concepts. Our belief that nature must have one true self, one consistent clockwork for us to tinker with, is revealed to be merely another human belief and not necessarily the way things are.
In a fundamental way Bell's discovery allowed physicists to test Bohr's claimed epistemological discovery. A test was now possible to see if the subatomic realm had a true self independent of our measurements.
The hope that new experiments will lead us back to objective events in time and space is about as well founded as the hope of discovering the end of the world in the unexplored regions of the Antarctic. Werner Heisenberg
I think I can safely say that nobody understands quantum mechanics. . . . Do not keep saying to yourself ..."But how can it be like that?" because you will get "down the drain," into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that. Richard Feynman
To understand Bell's discovery and the eventual experiments, let us try an analogy first. Suppose we have a large group of runners. Half of the runners are tall and half are short. Suppose that each of the short runners and each of the tall runners has a twin. Each of the twins will begin running at the same point, but will run a course in the opposite direction to a finish line that is the same distance from the original point of departure. Suppose also that each runner will run the course at the same speed, and that the spacing between the times when each runner leaves is such that no runner will be able to overtake the one immediately preceding him. No tall runners will overtake short runners or vice versa. Imagine then a continuous stream of runners leaving the original point and running in opposite directions. We might have something like this: Two short runners leave the starting point one after the other simultaneous with their respective twins, then two tall, then two short again, then one tall, and one short after that, then two tall, and so on. Suppose that overall the pattern is random. Suppose further that the contingencies of the course and physical training of each runner are such that many of the runners will not finish. Now we are ready to carry out the implications of our thought experiment. Suppose each twin has a strong desire to finish if and only if the other does. Our common sense would predict that finishing together is not likely. Suppose one of the short runners pulls a muscle just before the finish line. How likely would it be that the twin, running on an independent track, separated by a considerable distance, either knows this and decides to stop running or pulls a muscle also and does not finish? In other words, if we were to observe the runners finishing and established a mathematical correlation of completion, we would not expect it to be very high. Suppose that about 90 percent of the tall and short runners did not finish; it would not be likely that every time a short or tall runner finished or did not finish, the respective twin finished or did not finish as well. If we found the random result at one finish line to be T, T, S, T, S, S, T, S, we would not expect this result to be highly correlated or equal to the result at the other finish line. We would expect an inequality in the results.
There is one possibility, however, where the results could be highly correlated. Suppose each runner carried an electronic pager, such that whenever a runner knew they could not finish, he would signal the twin not to finish. In other words, if the runners could communicate, a very high correlation could be established.
Suppose though that we change our thought experiment a little. This time we will control, at one finish line, which runners finish and which ones do not. Suppose at a point immediately before one of the finish lines we set up a fork in the course, such that the short runners must take one path and the tall runners another. Suppose further that we have control over an electronic switch that closes each path by throwing up a barrier for either the short or tall runners. By randomly changing the switch we can change which path is open and which type of runner finishes. It is important to be able to do this after the runners have already left. Otherwise the runners could know ahead of time what kind of course they must run and adjust their actions accordingly. Suppose that the barriers are so close to the finish line, and we are able to switch the barriers so rapidly, that there is no time for each twin to signal the other whether he is going to finish or not. Now clearly there could not possibly be a very high correlation. It would be a strange result, indeed, if even most of the time when a tall runner finished, his twin also finished, and most of the time when one did not, his twin did not, and likewise for the short runners.
We assume that the local conditions at a barrier cannot instantaneously influence the local conditions at the other finish line. This locality assumption is an inherent part of our normal view of reality. We assume that the runners are independent individuals who will face independent conditions at independent places. What Bell showed is that if this assumption is correct and also applies to the subatomic realm, then the results we obtain in the subatomic realm with particles should reflect the same kind of inequality in correlation we expect to find in our macroscopic realm of short and tall runners.
Quantum theory, on the other hand, predicts an entirely different result for subatomic particles. Because it is incorrect to refer to subatomic particles as having any definite state with a definite place until a measurement takes place, an analogous runner's example to what happens in the subatomic realm would be the following: Our runners do not exist as definite runners until they are observed to finish, and a measurement at one finish line will instantaneously produce a correlated set of characteristics at the other finish line! From a quantum perspective, the locality assumption is denied; it is incorrect to think of our runners as real independent entities, in real independent places, experiencing real, local independent circumstances. Instead, between the time we see them leave and finish, our runners are a "superposition of states" of existence. They are neither tall, nor short, nor fast nor slow, but all these potential states at once.
If quantum theory is true, an analogous experiment in the subatomic realm should result in a significant violation of Bell's inequality deduction, because it is incorrect to think of subatomic particles as independent things with definite properties until a measurement takes place. If experiments are devised where "twin" particles are created and fly off in opposite directions like our runners, then quantum theory predicts that there will be a high correlation of the particle states when they are measured at a quantum finish line, because a measurement of one particle instantaneously collapses a wave function of potential (or entangled) states, a wave function that was created at the time of the twin particle creation.
||The Aspect Experiment|
Nature loves to hide. Heraclitus
My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose. . . . I suspect that there are more things in heaven and Earth than are dreamed of, or can be dreamed of, in any philosophy. That is . . . why I have no philosophy myself, and must be my excuse for dreaming. J.B.S. Haldane
Physics tells us much less about the physical world than we thought it did. Bertrand Russell
Because the locality assumption seems so obvious to our common sense, and because the technological tools were not sufficiently developed to conduct the proper experiments, recognition of the significance of Bell's work was slow in coming. A decade after Bell published his work intense discussion and experimental work finally began. As is so often the case in science, the results of the first experiments were inconclusive. By the 1980s using a reliable experimental design results supported decisively that in the subatomic realm Bell's inequality is violated and the predictions of quantum theory are correct. The results were consistent with the interpretation that the measurement of a subatomic particle at one finish line instantaneously determines the state of its twin at another finish line, regardless of how far the two finish lines are apart.
In the realm of subatomic particles our runners are replaced by mathematical objects with attributes such as "charge," "spin," "velocity", and "momentum." We naturally tend to think of these attributes in the same way we think of the attributes of our runners. Just as we think of each runner as a real independent body with definite characteristics such as being short or tall, fast or slow, we are more comfortable thinking of a particle having a real location or a real spin. Quantum physics, however, seldom allows us to be comfortable. Consider quantum spin. What kind of real attribute requires a subatomic particle to turn around twice before it shows its original face! Imagine looking at a position on the Earth from the Moon, say New York, and watching the Earth spin around twice before New York is visible again.
As bizarre as quantum attributes are, quantum physicists have learned how to deal with them mathematically and even set up experiments which create twin particles with opposite spin. The most notable, and most conclusive, we will call the Aspect experiment.(4) Using polarization, a property that can be thought of as similar to spin, physicists tested Bell's inequality prediction.(5) Atoms were excited to produce twin photons of light that sped away with opposite polarization. Methods were developed to test the states of the photons at their respective finish lines. In many respects this experiment was analogous to our thought experiment with the barriers and electronic switch. Bell's inequality theorem was violated. The spins of particles at distant finish lines were highly correlated. (In this experiment the main interest was in how often the photons at different finish lines would be blocked.) Because there was an analogous switching device, there was no possibility that a signal could be sent at a normal cosmological speed (the speed of light) causing the particle's spin to be correlated.(6) In summary, the result was as fantastic as our hypothetical, unlikely, runners thought experiment, where we find to our amazement, in spite of all of our precautions, that most of the time when a tall runner finishes or does not finish, so does the twin, and most of the time when a short runner finishes or does not finish, so does the twin. There is now little doubt that a violation of Bell's inequality is a fact of life. If there is a hidden reality with forces influencing the results of our paradoxical measurements, these forces must travel faster than the speed of light. They must be instantaneous.
It is important to realize that the violation of Bell's inequality is a "factual" demonstration that at least one assumption of Einstein's realism must be false, what we referred to above as the locality assumption. To accept the totality of Einstein's realism we must assume that the local conditions at one finish line could influence the local conditions at the other finish line only if the two locations are linked by a causal chain whose transmission of effects does not exceed the speed of light. In other words, if reality consists of separate objects, then one object cannot influence another object unless some sort of signal or influence travels from one object to the other during some amount of time. If the movement of one object "instantaneously" influences the movement of another object, then they are not really separate objects. In addition, if someone is standing on one side of a dark room with a flashlight, the flashlight must be turned on before an object can be illuminated on the other side of the room. Recall in Chapter 7 that some very strange results are possible if the speed of light can be exceeded. Our mother astronaut could return to Earth and be involved in a fatal automobile accident before her child was conceived and before leaving for her space voyage. Thus, for many reasons, a hidden force travelling faster than the speed of light is ruled out as a possible explanation for the puzzling results of quantum experiments. The Aspect experiment shows that we must reject the totality of Einstein's realism, but not necessarily all possible versions of realism. For instance, the entire universe at the subatomic level could be one interconnected object.
The results of the Aspect experiment and the violation of Bell's inequality are also consistent with the Copenhagen interpretation: Quantum objects should not be considered things until a measurement takes place. Unfortunately, the implications of this interpretation for the nature of reality are philosophically disturbing for most physicists. Thus, most physicists accept the pragmatic aspect of the Copenhagen interpretation and ignore the reality question. The reality question is something for "the philosophers" to worry about. This response is often portrayed as a sophisticated, modern point of view: physics should not be concerned with futile philosophical questions, but keep to the business of predicting results and applying quantum mathematics to novel situations such as computer technology, fiber optics, and superconductivity. By any standard this approach has been very successful. Today, even quantum crytographic devices are becoming a reality, allowing the transfer of money between banks allegedly guaranteeing absolute secrecy. By using pairs of entangled photons to send information, any electronic interference from an eavesdropper immediately disturbs the quantum entanglement and signals a breach of security as well.
However, is the instrumentalist approach any different from the reaction of past scientists to Ptolemy's epicycles, Copernicus's circles around invisible points, or Newton's gravity?
|Quantum Ignorance and Reality|
No language which lends itself to visualizability can describe the quantum jumps. Max Born
Reality is the real business of physics. Albert Einstein
For many, the reality question beckons still. The history of physics, and science in general, shows that the traditional pursuit of a deep objective truth is not just an idle ivory tower game. A quest for a deep understanding of reality has been valuable not only for its own sake but for the purpose of maximum practical application as well. The history of science has demonstrated repeatedly that when we understand the way things are at a deep invisible level, we are better able to understand, control, and predict the visible world in which we live. Until quantum physics, the vast span of scientific endeavor has vindicated Einstein's simple vision: The better we have been able to understand the invisible mechanism of the cosmic clock, the better we have been able to understand the motions of its visible hands. We may not be able to see Kepler's ellipses nor Newton's gravity in the starry night, but an understanding of these veiled realities has enabled us to embrace the night sky -- to predict, to control, to see, to explore -- in a manner undreamt of by the ancients who so patiently and relentlessly watched this surface reality. Other examples abound: The understanding of the molecular and atomic constitution of matter has enabled us to deal with the surface experiences of heat, temperature, and pressure; by understanding a deeper level of reality, we have been able to create objects that do not exist in nature, such as plastics; and now, by understanding the invisible structure of DNA we are controlling the development of life itself, with many practical applications in agriculture and medicine.
Is it over? The Copenhagen interpretation implies a strange kind of ignorance -- call it quantum ignorance. According to Bohr, it is a mistake to search for a hidden, deeper mechanism that will explain the results of quantum measurements, because between measurements there is nothing there to know, that is, nothing there that can be conceptualized in human terms. This is nature's way of educating us, of revealing its ultimate message: "Picture me with your human pictures if you must, but do not take your pictures too seriously." According to Max Born, another contributor to this interpretation, "No language which lends itself to visualizability can describe the quantum jumps."
For those sympathetic with Einstein, there must be something more; the results of quantum experiments must be only an example of what can be called classical ignorance. There must be something there that we are "disturbing" when we interact with it in attempting to measure it. We are ignorant of why quantum events happen as they do only because we do not know all the forces acting on subatomic particles, just as we cannot predict each throw of the dice in a dice game, because there are too many minute factors involved and because any attempt on our part to measure these factors in the act would disturb the results. In the case of dice there are other ways of demonstrating the existence of these factors, and thus we have every reason to believe that they are there, even if we cannot control them.
Bell's theorem and the consequent experiments do not rule out some kind of realism, that some kind of hidden force or reality is at work in the subatomic realm. They do demonstrate, however, that these forces, if they exist, must be very strange forces that are capable of propagating instantaneously regardless of distance. If our finish lines for subatomic particles were billions of miles away, the violation of inequality would be the same. If one of our finish lines was located in the vicinity of the star Betelgeuse, 540 light years distant, and the other on Earth, quantum physics predicts the same results. The results of Bell's theorem and the Aspect experiment show not only that quantum theory is a complete theory but also that any interpretation of quantum physics must incorporate the fact of instantaneous action.
So what kind of a reality do we live in? Notice that even the language of this question is misleading. To ask what kind of a reality we live in suggests that there is one reality independent of human beings and our attempt to know and measure this reality. Human language has evolved in a context of ordinary macroscopic reality. So how can we even begin to describe the subatomic realm? If it is a mistake to think of the electron as a thing with a definite place, with a definite velocity, until "it" is actually observed with a measurement, then it is difficult, to say the least, to understand how an "it" can exist without a location prior to a measurement which then gives it a location.
The concept is less difficult mathematically but no less strange. Mathematically, quantum physics allows a distinction between the static properties of the electron, such as "charge" and "mass," and the dynamic properties, such as "position" and "velocity." In this way most physicists believe that they can avoid versions of idealism, such as that of the eighteenth-century Irish philosopher and bishop George Berkeley, who taught that physical matter possessed reality only insofar as it was perceived by a mind. Put more dramatically, Berkeley believed that only mind or consciousness exists. For Berkeley, the entire physical universe is only an idea in the mind of God. Here is how Nick Herbert in his Quantum Reality describes the reaction of most physicists:
In other words, almost all physicists are convinced that something is out there, even though they are convinced that whatever it is, it will not conform to classical attempts to describe reality. But how can there be some "thing" without there being an independent "place" for this something to be? When we think of things like ordinary runners or elementary particles, we assume that they must have independent, objective attributes. What would be left if we took away from a tall runner his tallness, his speed, and his individual identity of being in one place? What kind of a runner could exist that was both short and tall, fast and slow, and neither short nor tall, fast nor slow? What kind of a runner could exist that only became a tall runner after we observed him at the finish line? Whatever they are, quantum objects are not ordinary things.
|A Paradigm for the Twenty-First Century?|
The observer is never entirely replaced by instruments; for if he were, he could obviously obtain no knowledge whatsoever .... they must be read! The observer's senses have to step in eventually. The most careful record, when not inspected, tells us nothing. Erwin Schrödinger
According to Nobel laureate Richard Feynman, we "can safely say that nobody understands quantum mechanics." Consider, however, the following provocative possible paradigm for our time.
In Chapter 6 we saw that the paradigm of Newtonianism involved a combination of epistemological and metaphysical assumptions: What is real does not depend on us, and reality is reducible to small independent particles of physical matter and empty space; thoughts, ideas, colors, emotions were all considered to be secondary realities, as not real, but rather the result of the movement and interactions of particles. This view, which we will call metaphysical reductionism, is seriously contradicted by the science of the twentieth-century, particularly the Copenhagen interpretation. What is real does seem to depend on us and our method of questioning nature. As the physicist E.P. Wigner has claimed, a measurement cannot legitimately be said to have taken place until it is acknowledged by the conscious awareness of a human being. Far from being a secondary reality, consciousness has a much greater significance in quantum theory. We confront the world with the filters of our human thoughts about the world, and nature conforms to these thoughts to some extent. A reality becomes manifest based upon the thoughts behind one of our experiments. We do not measure reality as Newton and all classical physicists believed; we measure the "relationship" between reality and our thoughts.
In the quantum realm it is not possible to pin down a consistent reality, and nature teaches us in the process not to take our thoughts about reality too seriously, on the one hand, and to take them very seriously, on the other hand. We should not think of our human concepts of "particle" and "wave" as reflecting an independent reality, but we have been forced to recognize the creative power of human concepts. The mathematics of quantum theory does not picture a precise clock with definite parts but a strange indefinite cosmic substance capable of manifesting an infinite number of fleeting faces. Quantum theory pictures the particles that make up everything that we touch and feel not as little, hard, definite, independent things, but a tangle of possibilities that are entangled with every other tangle of possibilities throughout the universe. As with the particles in the Aspect experiment, the particles in my body may be connected in some way with the particles of your body, and these in turn with particles in a distant sun, in a distant galaxy, billions of light years away.
There is the immense "sea" of energy. . . . a multidimensional implicate order ... the entire universe of matter as we generally observe it is to be treated as a comparatively small pattern of excitation. This excitation pattern is relatively autonomous and gives rise to approximately recurrent, stable and separable projections into a three-dimensional explicate order of manifestation, which is more or less equivalent to that of space as we commonly experience it. David Bohm
There is little disagreement today among physicists and philosophers of science that the metaphysical reductionism of the seventeenth, eighteenth, and nineteenth centuries has been destroyed by the science of the twentieth century. But there is no consensus on a replacement. The results of relativity and quantum theory have sent physicists and philosophers of science scurrying in many different philosophical directions. Although most physicists have accepted the practical dictates of the Copenhagen interpretation, David Bohm, among others, has refused to abandon entirely the realism of Einstein, opting instead for a radical neorealism. For Bohm, the Aspect experiment does not disprove a hidden reality, but only one that consists of separate things! A universe of "undivided wholeness" is consistent with all the experimental results. A real universe exists independent of our observations of it, but it is not like the room that I am in now: a bowl of space with apparent independent objects separated into different locations. This normal perception is only my human macroscopic view of the room. "Underneath," so to speak, from a perspective of a multidimensional hyperspace or superspace this appearance of separateness can be seen to melt like ink dots in water.
Mathematical equations that literally describe a hyperspace, a multidimensional space, which scientists often cryptically referred to as "configuration" or "phase" space, are common in the mathematics of modern physics. As we have noted, most physicists have been taught during their university educations to think of these as only mathematical devices because it makes no sense to use ordinary language or pictures in an attempt to ascribe a reality to such bizarre number juggling. Bohm, however, following the epistemological lead of Einstein, suggested that what works in our equations may point to an underlying reality.
Consider the following analogy from Bohm's Wholeness and the Implicate Order. Imagine a fishbowl with fish slowly swimming round and round, occasionally darting here and there, changing direction unpredictably. Imagine two TV cameras filming the activity of the fish from different points of view. Imagine that in another room a person is sitting watching two TV sets receiving the transmissions from the two cameras. This person at first might think that he is watching two different fishbowls and fish movements, except that he would notice an amazing correlation in the movements of the two sets of fish. Every time one of the fish in one TV screen unpredictably changes direction by darting to the left or right, a fish in the other screen changes directions also. After watching this activity for awhile, this person should be able to infer that the separate images are different perspectives of one reality. According to Bohm, this is what the long road of scientific endeavor, culminating in the experiments of quantum physics, has revealed to us: Our normal world of separate objects is but separate images of one underlying reality. We set up our three-dimensional experiments and then wonder how particles separated by light-years can be correlated, but from the standpoint of hyperspace the particles are right "next" to each other, so to speak; the two apparently separated particles are the same particle, just as the two apparently separated fish are the same fish.
|Flat Land and Hyperspace|
All things will be in everything; nor is it possible for them to be apart, but all things have a portion of everything. Anaxagoras
The various particles have to be taken literally as projections of a higher -dimensional reality which cannot be accounted for in terms of any force of interaction between them. David Bohm
Because of our Kantian-Newtonian filters, it is impossible for us to imagine what a multidimensional hyperspace is like.(7) We can, however, get an idea of what existence in a higher dimension is like by comparing our three-dimensional existence with a hypothetical two-dimensional existence called Flat Land.
Imagine a world that is flat like a piece of writing paper upon which flat two-dimensional creatures live. Imagine that on this world there are flat two-dimensional houses and flat two-dimensional creatures that look like triangles, squares, and circles. Because they are two-dimensional, these peculiar characters can go about their two-dimensional business by moving forward or backward, left or right, but "up" and "down" have no meaning in this world. Relative to this world, we would find that three-dimensional creatures like ourselves have supernatural powers. We could peer into their houses from above and watch what they are doing; we could cause strange events to happen at great distances simultaneously; we could cause correlated behavior in objects that seem separated to our flatlanders. We could even cause strange objects to appear out of nowhere. We could easily produce quantum jumps.
Suppose we picked up an ordinary salad fork from our three-dimensional world and poked it in and out of this two-dimensional world. A flatland creature observing this event from its two-dimensional world would see only four mysterious dots appear from nowhere, move around in a coordinated manner, and then vanish as mysteriously as they appeared. If we picked up one of these two-dimensional creatures and pulled it up into our three-dimensional world, the poor creature would have a mystical experience; it would experience a reality for which there was no language. If we then placed the creature back onto its two-dimensional world, perhaps where a number of his friends are discussing his mysterious disappearance, the flatlander would appear to have materialized out of nowhere. If the creature attempted to explain to his friends in flatlander language what he had experienced, he would undoubtedly sound like a crazy fool, much like the enlightened man in Plato's cave.
According to Bohm, our observations of electrons and other subatomic phenomena in our three-dimensional laboratories with three-dimensional equipment are not the result of an act of creation of consciousness, but rather an interfacing of a multidimensional reality with a three-dimensional one. Just as our flatlanders experienced mysterious unpredictable events that were explainable from the point of view of another dimension, so the behavior of electrons and other subatomic phenomena are understandable from the point of view of an overlaying, but concealed, "implicate" hyperspace. Just as the actions of the four correlated dots produced by the three-dimensional fork are seen to be one reality, so our entire world of apparent separate particles that seem to make up separate objects is but a manifestation of one undivided hyperspatial whole.
The philosophical virtue of such an interpretation of the mathematics and experimental results of quantum physics is that the realism of our normal three-dimensional world is preserved. When we walk out of a room, the room is still "there" in a sense. From a hyperspatial perspective, more than a three-dimensional room may be there, but the three-dimensional room is still there for any three-dimensional creature to see. We do not create the room with our consciousness out of some strange indeterminate nothingness.
By the act of observation we have selected a "real" history out of the many realities, and once someone has seen a tree in our world it stays there even when nobody is looking at it. John Gribbin
Physics is neither epistemologically nor ontologically neutral. F.S.C. Northrop
There is no logical necessity for believing in one universe any more than there is for believing that Earth is the center of existence. Another interpretation of quantum physics that attempts to preserve the general philosophical position of realism is known as the Many Worlds interpretation. This interpretation preserves realism with a vengeance. In the 1950's Hugh Everett III, then a graduate student at Princeton University, decided to see what would happen if the mathematical equations of quantum physics were consistently taken literally. To see how this would work let's return to our previous experiments.
Recall the experiment attempting to prove that single particles of light pass through only one channel (Figure 8-2a). The result of detecting only one whole unit of energy at detector A or B was consistent with this interpretation. Yet a particle interpretation was not consistent with the outcome of the experiment with totally reflecting mirrors replacing detectors A and B. The Schrodinger equation depicts waves of some sort passing through both channels, and the experiment with totally reflecting mirrors demonstrates that light, as a wave that splits into two waves, is in both channels. According to the Many World's interpretation there is a simple, but shocking, explanation for the first result. The Schrodinger equation depicts the radiation in both channels as real; the reason we only observe it at one detector or the other is because when a measurement is made the world splits into two equally real worlds! When the radiation is detected at A, it has also been detected at B. We do not detect it at B, because B is an event taking place in another world! And if you ask who is in this other world to detect the different result, the answer is equally shocking -- the split versions of the experimenters who detected the radiation at A in the other world.
According to this interpretation all the possibilities delineated by the Schrodinger equation are real. In making an observation of a particular possibility we are not collapsing a wave packet or creating a reality from a number of possibilities. Rather, like a road with many forks, we are choosing a world to travel on from many possible worlds. All the alternate worlds are paths in hyperspace; they are equally real, but we are probably forever cut off from them. In every observation we are choosing a branch of reality. If the Copenhagen interpretation implies that nothing is real independent of observation, the Many Worlds interpretation implies that everything is real. We do not create a universe with an act of observation; we choose a universe that is already there as a possible path. According the astrophysicist and science writer John Gribbin, an enthusiastic supporter of this interpretation, "By the act of observation we have selected a 'real' history out of the many realities, and once someone has seen a tree in our world it stays there even when nobody is looking at it."
In the two slit experiment when an attempt was made to see if the photons pass through both slits (Figure 8-1c), we found the radiation passing through only one slit or the other. According to Gribbin, in his book In Search of Schrodinger's Cat, here is the proper interpretation of what the electron is doing.
This means, however, that just as there are many routes to the future, there are many versions of "us" that will follow these paths. Because every observation splits the path we are on into alternate universes again and again, there are literally billions of alternate paths through hyperspace. These alternate worlds, however, are not parallel to us, as in so many science fiction novels, but like our three-dimensional view of two-dimensional flat land, they are at right angles. Somewhere in this hyperspace there is a world where the South won the American Civil War; a world where the Spanish Armada defeated the British; a world where John F. Kennedy was not assassinated, and a world where World War III happened and the human species is extinct.The same kind of thinking that led to this interpretation of the quantum mathematics and experiments has more recently produced theories on the origin of our universe and the cause of the Big Bang. According to one version of these theories, the Big Bang and the parameters of our particular universe make up simply one particular bubble in an infinite sea of other bubble universes. Just as the followers of Einstein have sought for a deep explanation of quantum phenomena, so scientists have sought a "Theory of Everything" that would explain exactly why we have the type of universe that we do. Scientists worry about what they call "undetermined parameters." For instance, in our universe the electron and the proton have a particular mass and charge. Why do they have these values? If any of the values were just a little different, the universe would be completely different. Scientists are seriously working on theories that will explain these values as a particular manifestation of a more fundamental process of universe creation, just as a climatologist can explain why the weather in one location on the Earth is different than another. Our universe would then be just a little bubble created along with an infinite number of other bubbles by some process that stirs up an infinite sea of hyperspace.(9)
Physics, too, is only an interpretation of the universe, an arrangement of it (to suit us, if I may be so bold!), rather than a clarification. Friedrich Nietzsche
My mind, in an undisciplined way, detects the cosmic within the nitty-gritty and the trivial within the infinite. Harold Morowitz
The Participatory Universe
Some scientists have found it less shocking to carry out the implications of the Copenhagen interpretation than to believe that each moment we are splitting into 10100 equally real copies of ourselves. The distinguished American physicist John Wheeler argued that we must abandon the basic tenet of traditional realism -- that the universe is in some sense "sitting out there" for us to uncover. In its place, according to Wheeler, we must boldly embrace the concept of a "participatory universe."(10)
Adherents of this view claim that all vestiges of traditional realism must be abandoned. Both Bohm's neorealism and the Many Worlds interpretation are but symptoms of our inability to give up a traditional metaphysics. There is no clocklike world in any sense sitting out there for our observational benefit alone. We do not observe "the real world"; we participate with reality by creating a reality for us. More precisely, we do not create reality, we select a concrete reality from out of an intermingled dance of intangible possibilities. (In the Many Worlds interpretation, all the possibilities are concrete.)
This concept is not as difficult to understand as it may seem. Wherever you are right now there are many hidden, potential manifestations of energy that all of us have come to take for granted in modern life. There are many potential channels of electromagnetic information. Although we cannot see them or feel them, there are many AM, FM, TV, cell phone, text and paging signals passing by us at any given moment. They are both here and not here. To make these signals of information manifest, to make them concrete, we must "tune them in"; we must have a device like a radio, TV, pager, or cell phone to collapse the indefinite electromagnetic waves into concrete electronic digits of information. The human mind is like a radio receiver stuck on one channel. When we set up our three-dimensional laboratory equipment, when we peer into our big telescopes and see galaxies millions of light years away, we participate with the infinite by manifesting one of its faces. It is not a mask; it is definitely there. But only as we observe it; just as radio music is music only as we tune it in.
Our confrontation with the microcosmos has taught us this: The results of our experiments are due to our being on one channel, but the microcosmos reveals to us, both through the gift of mathematics and observational paradoxes, that there are many other channels. It has taught us that when we go out on a cool, clear night and peer through a pair of binoculars at the Andromeda galaxy and receive the light that in our normal mode of thinking is two million light years old, we are instantly creating in a sense a two million year old past. The universe, in a sense, is here because we are here. There is still a kind of a past even if I am not looking, just as there is potential music in my room, even if my radio is off.
For if those who hold that there must be a physical basis for everything hold that these mystical views are nonsense, we may ask -- What then is the physical basis of nonsense?...In a world of ether and electrons we might perhaps encounter nonsense; we could not encounter damned nonsense. Arthur Eddington
[We must] continue to insist on the centuries long traditon of science in which we exclude all mysticism and insist on the rule of reason. And let no one use ... [quantum] experiment to claim that information can be transmitted faster than light or to postulate any so-called "quantum connectedness" between separate consciousnesses. Both are baseless. Both are mysticism. Both are moonshine. John Archibald Wheeler
In our teaching we have an obligation to help our students to think about the uncertainties and ambiguities of nature as they are found at the interface between the known and the conjectural, but we have also...the higher responsibility to help them function on this side of that interface. On this side -- well back from the exciting and esoteric frontier where Einstein and Bohr still wrestle to a draw, our students are presented with obstacles to clear thinking and daily assaults against science and against the integrity and reasoning of the people who do it. Charles Stores, a master teacher.
Mysticism and the Convergence Thesis
One more interpretation of the implications quantum physics deserves some comment. It is a very controversial interpretation because it claims that the results of modern science have validated a particular religious orientation. The possibility of such a development is one of the reasons scientists are often reluctant to communicate with the general public. However, the possible misuse of an idea does not prove the idea false.
For the purpose of identification let's refer to this final interpretation as the convergence thesis. Essentially, this view argues that our confrontation with the quantum realm has demonstrated that Western science, founded upon the logic and philosophy of the ancient Greeks, has, after travelling a much different philosophical path, converged with the philosophy of the East, especially the mystical philosophies of Hinduism and Buddhism. This view was popularized in the 1970s by physicist Fritjof Capra in The Tao of Physics and philosopher Gary Zukav in The Dancing Wu Li Masters. According to Capra, "What Buddhists have realized through their mystical experience of nature has now been rediscovered through the experiments and mathematical theories of modern science." And Zukav said, "Hindu mythology is virtually a large scale projection into the psychological realm of microscopic scientific discoveries."
For many thousands of years the mystics have had a cosmological, ontological, and epistemological view of things that the Western world is just beginning to understand. Cosmologically, Western science has understood only recently that the universe is remarkably old. In 1965 the temperature of the universe was measured for the first time, eventually resulting in our present estimate of the age of the universe as about 14 billion years. In the ancient literature of the East one does not, of course, find such precise figures. Instead there are analogies such as the following. Imagine an immortal eagle flying over the Himalayas only once every 1,000 years; it carries a feather in its beak and each time it passes, it lightly brushes the tops of the gigantic mountain peaks. The amount of time it would take the eagle to completely erode the mighty Himalayas is said to be the age of only the present manifestation of the universe. Predating modern science by thousands of years, such a conception of time is remarkable, especially when it is compared to the slow realization of Western science and religion to the possibility of a less humanlike time scale.
Ontologically, Eastern mysticism is also consistent with the results of quantum physics. The mystics have always rejected the idea of a hidden clocklike mechanism, sitting out there, independent of human observation. The number one truth is that reality does not consist of separate things, but is an indescribable, interconnected oneness. Each object of our normal experience is seen to be but a brief disturbance of a universal ocean of existence. Maya is the illusion that the phenomenal world of separate objects and people is the only reality. For the mystics this manifestation is real, but it is a fleeting reality; it is a mistake, although a natural one, to believe that maya represents a fundamental reality. Each person, each physical object, from the perspective of eternity is like a brief, disturbed drop of water from an unbounded ocean. The goal of enlightenment is to understand this -- more precisely, to experience this: to see intuitively that the distinction between me and the universe is a false dichotomy. The distinction between consciousness and physical matter, between mind and body, is said to be the result of an unenlightened perspective.
Epistemologically, our so-called knowledge of the world is actually only a projection or creation of our thoughts. Reality is ambiguous. It requires thoughts for distinctions to become manifest. We have seen that in the realm of the quantum, dynamic particle attributes such as "spin," "location," and "velocity" are best thought of as relational or phenomenal realities. It is a mistake to think of these properties as sitting out there; rather they are the result of experimental arrangements and ultimately the thoughts of experimenters. Quantum particles have a partial appearance of individuality, but experiments show that the true nature of the quantum lies beyond description in human terms. Our filters produce the manifestations we see, and the result is just incomplete enough to point to another kind of reality, an ambiguous reality of "not this, not that."
For the mystic, the paradoxes of quantum physics are just another symptom of humankind's attempt to describe what can only be experienced. We are like a man with a torch surrounded by darkness. The man wants to experience the darkness, but keeps running senselessly at the darkness with his torch still in hand. He does not realize that he must drop the torch and plunge into the darkness. The proliferation of philosophical interpretations of quantum physics is a symptom of the shipwreck of a traditional Western way of understanding, of our inability to "let go" of our Western torch -- our traditional logic, epistemology, and ontology. It is also a symptom of our inability to let go of our egocentricity, our persistent attempt to define everything in purely human terms, as if we are somehow special and separate from the rest of the universe. Like a nervous, self-centered teenager at a party, concerned only with what others think of him, our entire field of vision and understanding is narrowly defined in terms of a "me." Because of our fear of letting go, there is much that is right in front of us that we are missing.
According to this interpretation, the mathematics is complete just as it is. What the Schrodinger equation depicts for microscopic objects is also true for any macroscopic object. The universe is not full of separate objects, of separate people and places. Rather, it is an unbounded field of entangled possibilities. Because of the level of our conscious awareness, we fail to realize that duality, ambiguity, and interdependence are the rule rather than the exception. Mathematics may be one of the closest languages we have to representing these truths. All languages, however, are ultimately inadequate. Myths, stories, analogies, pictures, mathematical equations -- all such symbolic systems can but point to that which can only be fully understood through a deep meditative experience.
In the episode entitled "The Edge of Forever" in the "Cosmos" television series, Carl Sagan visits India, and by way of introducing some of the bizarre ideas of modern physics, he acknowledges that of all the world's philosophies and religions those originating in India are remarkably consistent with contemporary scenarios of space, time, and existence. However, adamantly skeptical of the knowledge value of a nonrational mystical intuition, he concludes that although these religious ideas are worthy of our deep respect, this consistency is obviously only a "coincidence." Using natural selection as a model, he proposes that it is "no doubt an accident," because given enough time and possible proposals, given enough creative responses to the great mystery of existence, some ideas will fit the truth just right.
Other critics of the convergence thesis have not been as charitable. They argue that it is just plain silly to interpret an ancient belief system, founded upon certain psychological needs and within a historical context, in terms of any modern perspective. It is obvious, they argue, how the Hindu and Buddhist beliefs could soothe people living under extreme conditions. If our day-to-day reality is but a fleeting manifestation, then the vicious misfortune and meaningless suffering of this world are not real. For these critics, the methodology of psychological need as an origin of these ideas implies there is no connection. By understanding the obvious psychological motivation for a set of beliefs, it is argued, one can question the truth of these beliefs. To further suggest that there is any connection between these beliefs and the results of rigorous experimental science is ludicrous.
Defenders of the convergence thesis argue that these arguments are flawed. If the ideas of Hinduism and Buddhism are simply the result of a lot of guessing, and the serendipitous contingency of evolutionary processes the appropriate model, then shouldn't all the guessing that takes place over time should be consistent with a macroscopic environment, not a microscopic environment with which a primitive people have no experience? And even if it is true that a belief system serves a set of psychological needs, does this prove the belief system false? Many scientists are also surely motivated for many reasons to hold the beliefs they do: a philosophical perspective, the need for certainty, the need for security (be it a government grant or tenure at a prestigious university). That scientists have biases and motivations to believe what they do does not prove that what they finally believe is false.
Both of these arguments, however, do reveal a sobering point. The philosophical consistency between Hinduism and Buddhism and the results of modern science does not prove much by itself. Historically, we have seen many instances of a philosophy or a religious view being consistent with the science of a time, and a consequent rush to claim that the new science validates a religion or a philosophy. For both Copernicus and Kepler, the sun-centered system of the planets was consistent with their Neoplatonism and the idea that the sun was the "material domicile" of God. Similarly, for Bruno the sun-centered system was consistent with a larger universe and a greater God. For Newton a universe based upon the laws of universal gravitation was consistent with a conception of God as a master craftsman, a creator of an almost perfect machine who left a few defects with which to give Himself something to do. For some of the initial supporters of Darwin, natural selection was interpreted as a vindication of a philosophy of inevitable progress based upon a capitalistic economic system.
Perhaps the more pertinent question, applicable to all the interpretations of quantum physics, is not which offered paradigm is the truth, but which one will give us the most mileage? Which one, if followed as a guide, will be the most fruitful in stimulating the imagination of the next generation of scientists in devising new ideas, mathematical relationships, and experiments? In this chapter we have not given much attention to that area of modern physics that recently has gotten the most notoriety. In spite of the overwhelming success of the experimental demonstration that a traditional metaphysics of reductionism is inadequate, most physicists, concerned with the day to day demands of obtaining research grants and Nobel prizes, have simply filed such demonstrations away and continued with the Einsteinian quest, searching for more and more exotic particles, new "things" that will prove the supersymmetry theories, unifying all the known forces of nature and catapulting our understanding to the first microseconds of the universe and perhaps beyond.
I believe that certain erroneous developments in particle theory...are caused by a misconception by some physicists that it is possible to avoid philosophical arguments altogether. Starting with poor philosophy, they pose the wrong questions. It is only a slight exaggeration to say that good physics has at times been spoiled by poor philosophy. Werner Heisenberg
To see the world in a grain of sand.
And heaven in a wild flower;
Hold infinity in the palm of your hand.
And eternity in an hour. William Blake
What holds true in the world of electrons does not govern the world of chess and apples. James Randi
In spite of the tremendous explanatory, experimental, and technological success of quantum theory, physicists are still bothered today over the fact that the theory has not been unified with Einstein's general theory of relativity. Even more important, when our best physical theories are used to explain the origin, development, and current state of the universe, there remains an underlying lack of elegance similar to what bothered Copernicus, Kepler, and Galileo about the Ptolemaic universe discussed in Chapter 5. Just as retrograde motion was not rigorously determined by the Ptolemaic geometric machinery, so our current understanding of why the elementary particles have the properties that they do and why there are four forces in nature seems incomplete. For instance, why is a muan (mostly detected in cosmic rays from outer space) very similar to an electron except have a mass 200 times heavier? Why does a proton have the mass that it does? Why does a photon have zero mass? Physicists call these quantities undetermined "parameters," and like Copernicus and Kepler they want to find the God equation, one master principle or set of equations that explains everything.
Today, for physicists interested in such cosmological holy grails the place to be working in developing a career is in what is called String theory. Direct empirical evidence does not yet exist for the theory, and some physicists have estimated that it would require an accelerator like CERN (see Chapter 1) the size of a galaxy to produce the necessary energy for direct empirical evidence of the foundational ingredients of the theory. Nevertheless, the potential elegance and explanatory power of the theory are so great that thousands of physicists in the past several decades have dropped former projects to pursue the new theory.
According to this theory, all the particles of matter and the forces of nature might be explained by purely mathematical objects, tiny strings that vibrate in and out of various multidimensional spaces, called Calabi-Yau spaces. Just as music is made by the vibration of piano or violin strings, in String theory an electron is explained as a particular resonate pulsation of a string vibrating in a particular way in multidimensional space and a muan results from a different type of vibration. According to physicist Brian Greene,
Far from being a collection of chaotic experimental facts, particle properties in string theory are the manifestation of one and the same physical feature: the resonate patterns of vibration - the music, so to speak - of fundamental loops of string. The same idea applies to the forces of nature as well ... force particles are also associated with particular patterns of string vibration and hence everything, all matter and all forces, is unified under the same rubric of microscopic string oscillations - the 'notes' that strings play.(11)
It is important to note the possible philosophical implications of such a theory. The table my computer is sitting on is already seen as somewhat illusory by the standards of quantum physics. It is not really hard and solid. The hardness is simply a human perception based on how we physically feel the result of the interaction between the opposing negative electric charges from the electrons on the surface of our hands and the table. Our perception of hardness is actually the result of electromagnetic forces. Furthermore, the atoms in the table are 99.9% empty space, and if the Schrodinger equation is taken literally, a big "if" remember, the electrons are only mostly "there" in the table I see. Some of the energy of the electrons is smeared throughout the universe. Now, String theory goes even further. Not only are the electrons, protons, and neutrons not little solid particles of matter, they seem to be as ephemeral as music. To use Galileo's language, a point though that would certainly have shocked Galileo himself, particles of matter appear to be "secondary qualities." But what then are the primary qualities? Ultimately, what is reality made of?
Now, do not think that these
strings are like strings in our commonsense world. A piano
string is of course made of atoms, but the strings of
String theory are mathematical objects that can have a
certain mathematical tension and vibrate in certain ways,
but they are not made of anything more basic. They are
geometric objects. Most important, strings vibrate the way
they do due to the "spaces" they are in - the
multidimensional spaces. According to Brian
This means that extradimensional geometry determines fundamental physical attributes like particle masses and charges that we observe in the usual three large space dimensions of common experience . . . that . . . fundamental properties of the universe are determined, in large measure, by the geometrical size and shape of the extra dimensions.(12)
But what is the ontological status of these extradimensional geometric spaces? Democritus' solid little atom is surely gone. What should we think about metaphysical materialism in general? What we call matter and physical things seem to be made of mathematical objects. Defenders of Idealism will surely claim that these objects are thoughts or concepts, and that Plato basically had it right about reality over 2,000 years ago. Recall from Chapter 4 that for Plato the idea of a triangle was more real than any physical manifestation of a triangle. Matter is the illusion; ideas are real. Math existed before the physical universe. Now in String theory mathematical relationships make the universe that we see, and these mathematical relationships are not relationships between pieces of matter. They make the matter!
Einstein complained that quantum physics was incomplete because of unification problems and because he believed in an objective universe, not one created by our thoughts. What if String theory is successful? What are we to make of reality if the unification of physics implies thoughts are ontologically prior to matter?(13)The pursuit of String theory continues in earnest. Debates rage over the philosophical implications. One senses that nature is not yet ready to succumb completely to our latest gestures of understanding. Every past success at understanding has produced new mysteries. Why should it be any different now? There is every reason to believe that our romance will continue, that there are many mysteries left for a new generation of physicists. Although there have been many pretenders since the time of Kepler, no one has yet read the mind of God.
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Notes: (Click Back to return to text)
1. Technically these are known as the Photoelectric effect, Compton effect, Young and Davisson-Germer diffraction wave experiments, Stern-Gerlach interferometer experiments, Bell's inequality theorem and the Aspect experiments. (Click Back to return to text.)
2. Actually a diffraction pattern, a diffused piling effect, results, which is also a wave effect. So the wave effect shows particle characteristics, the individual hits on the film, and the particle effect shows wave characteristics, the diffraction pattern.
3. So called because much of the work done by Bohr, Werner Heisenberg, and others was done in Copenhagen, Denmark.
4. After the French physicist Alain Aspect, who was the leader of a team that conducted this crucial experiment. The results were published in an unassuming three page paper "Experimental Tests of Realistic Local Theories via Bell's Theorem," Physics Review Letters, Aug. 17, 1981.
5. Polarization is what makes Polaroid lenses and dark glasses possible. A Polaroid lens allows photons of light with only a particular spin orientation to pass through. Those without this orientation are blocked, thus selectively lessening the intensity of light that passes through.
6. Switching devices were activated by high-frequency waves at a rate 100 million times per second. Because the finish lines were 10 meters apart, no signal could be exchanged between the separated particles at the speed of light.
7. Some attempts at unifying all the known physical forces into a superforce have used mathematical devices that refer to between 11 and 26 dimensions.
8. John Gribbin, In Search of Schrodinger's Cat: Quantum Physics and Reality (N.Y.: Bantam Books, 1984), p. 241. The title is taken from a paradox first discussed by Schrodinger. If a cat is placed in a special box with a deadly vial of poison and a quantum device is used to trigger its release, then until we open the box to measure the state of the cat, the cat is both alive and dead. Like the electron, the cat is represented by a superposition of states. The Many World's interpretation solves this paradox by claiming that in one world the cat is alive and in another it is dead.
9. This process would not be a onetime event. It would be on-going with many universes being created before and after ours.
10. However, Wheeler has been very critical of those who would use this abandonment of realism as an excuse for believing in the occult or mysticism. See the next section.
11. Brian Greene, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory(New York: Vintage Books, 2000), pp. 15-16.
12. Greene, p. 206. Greene's emphasis.13. Although space does not permit us to discuss this further, it is worth noting that there are two types of Idealism, objective and subjective. For an objective idealist, ideas have an independent reality. Plato believed that the idea of a triangle existed even if there were no human minds around to discover it. For a subjective idealist, our thoughts create reality. For the philosopher Berkeley if there were no mind around, a tree falling in a forest would have no sound. In fact, there would be no forest. The type of idealism that Einstein objected the most to was subjective idealism, which seems to be implied by the Copenhagen interpretation. String theory seems to support objective idealism. Einstein may have approved of this type of Idealism, because he did believe in Spinoza's God, a God of pure consciousness and thought. Spinoza also believed studying mathematics was the closest we could come to in understanding God.
Quantum Reality: Beyond the New Physics, by Nick Herbert (Garden City, N.Y:, Anchor Press, 1985).
The Dancing Wu Li Masters: an Overview of the New Physics, by Gary Zukav (New York: Morrow, 1979), and The Tao of Physics: An Exploration of the Parallels between Modern Physics and Eastern Mysticism, by Fritjof Capra (Berkeley, Calif.: Shambhala, 1975).
Flatland--A Romance of Many Dimensions, by Edwin A. Abbott (IndyPublish.com, 2002)
The original version of this book was published in 1880. Several books have been written since to help the general reader and non-mathematician understand the possibility of dimensions beyond our common sense perspective on space. (See also, Flatterland: Like Flatland, Only More So, by Ian Stewart) In addition to making fun of our egocentric views of reality, Abbott also satirized the ethnocentrism of his Victorian England society.
Articles to Knock Your Socks Off:
"An Obstacle to Creating a Universe in the Laboratory," A. Farhi and Alan Guth, Physics Letters. 183 B (1987): 149-155.
"Are Superluminal Connections Necessary?", Henry Pierce Stapp. Nuovo Cimento 40B, no. 1 (1977): 191-204.
"Creation of the Universe from Nothing," Physics Letters. 117 B (1982): 25-28.
"Demonstrating Single Photon Interference," Arthur L. Robinson. Science 231 (February 14, 1986): 671-672.
"Einstein Was Wrong," Paul Davies. Science Digest, (April 1982): 40-41.
"Origin or the Universe as a Quantum Tunneling Event," Physical Review D 25 (1982): 2065-2073.
"Princeton University Dean of Engineering Justifies Psychic Research." Science News 116, no. 21 (November 24, 1979): 358-359.
"Testing Superposition in Quantum Mechanics," Arthur L. Robinson. Science 231 (March 21, 1986): 1370-1372.
"The Copenhagen Interpretation,"
Henry Pierce Stapp. American Journal of Physics
40 (August 1972): 1098-1116.
"The Quantum Theory and Reality," Bernard d'Espagnat. Scientific American 241, (Nov. 1979): 158-181.