Unamended Quantum Mechanics Rigorously Implies Awareness Is Not Based in the Physical Brain

Transcription

1 Unamended Quantum Mechanics Rigorously Implies Awareness Is Not Based in the Physical Brain Casey Blood, PhD Professor Emeritus of Physics, Rutgers University

2 1. The Basic Idea How could physics possibly imply awareness is nonphysical? The crucial point is that the highly successful theory of quantum mechanics gives many simultaneously existing versions of the physical world, including many versions of our brain. (To understand this very odd idea, see Schrödinger s cat, sec. 2.) But we are aware of only one of these versions of reality. The usual way of explaining this awkward mismatch is to assume the perceived world is made up of objectively existing particles electrons, atoms and so on, rather than the many-version wave function. But surprisingly, very surprisingly, when you carefully examine the interpretations of the relevant experiments, you find there is absolutely no evidence for particles; all the results can be accounted by the particlelike properties of the wave function alone (sec. 5). Another way to try to get around the many-one mismatch is to assume the wave function collapses down to just one version the dead cat version in Schrödinger s cat, for example, might collapse to zero, leaving only the live cat version. But there is also absolutely no evidence for collapse (sec. 6). Further, there are good reasons to believe that neither the particle picture nor the collapse picture of physical existence can be correct. Thus the most likely structure for physical reality is that only the wave function, with all its versions of reality, exists. (This is unamended quantum mechanics). But in this most-likely picture, one can prove (sec. 4) that awareness cannot be based in the physical brain. Its origin must be outside physical reality. The most straightforward way to picture this result is to suppose we each have a nonphysical Mind that looks in from outside physical reality and focuses on just one version of the quantum state of our brain (sec. 3).

3 2. Schrödinger s Cat This thought experiment is used to illustrate the idea that, under certain (often-occurring) circumstances, quantum mechanics gives several simultaneously existing versions of one s brain. A cat and a vial of cyanide are put in a box. Outside the box are a source of radiation and a detector of the radiation. The detector is turned on for one minute. If the detector registers 100 or more radioactive decays, an electrical signal is sent to the box, the vial of cyanide is broken, and the cat dies. But if the detector registers fewer than 100 decays, no signal is sent, and the cat lives. Classically and experientially, we will perceive either a live cat or a dead cat. But in the mathematics of quantum mechanics, the cat is both alive and dead at the same time. One part of the wave function of the cat corresponds to a live cat and another corresponds to a dead cat. Schematically, the wave function is [detector registers fewer than 100 counts] [cat alive] and [detector registers more than 99 counts] [cat dead] The results become even more absurd if we include an observer. The wave function is then [detector registers fewer than 100 counts] [cat alive] [observer s brain state corresponds to cat alive] and [detector registers more than 99 counts] [cat dead] [observer s brain state corresponds to cat dead] If you are the observer, there are two versions of you! But only one will correspond to your perceptual awareness, and quantum mechanics cannot say which one it will be. This leaves, as far as I can see, only two options for explaining why we perceive one particular version of reality: Either quantum mechanics is an incomplete description of physical reality and there is an additional single-version physical reality (particles or collapse); Or unamended quantum mechanics with its multiple versions of reality gives a complete description of the physical world, and the reason why we are perceptually aware of only one particular version is hidden in the perception process. Intuitively, we certainly expect the first. But there is no evidence for it, and there are strong arguments it is incorrect. This leaves only the second possibility. It can be shown to imply that each of us has a perceiving aspect which is outside the laws of quantum mechanics.

4 3. The Nonphysical Mind Interpretation In my opinion, the odds are considerably better than even that our premises no particles, no collapse are correct. What kind of reality does the idea of perception outside of quantum mechanics that is, outside physical reality imply? I suggest the following: Associated with each of us is a nonphysical Mind which is not subject to the mathematics of quantum mechanics (or, presumably, any other mathematics). That Mind looks into physical reality and perceives, or rather focuses its awareness on only one of the many quantum versions of our physical brain. It might focus on the version corresponding to a live cat, or it might focus on the version corresponding to a dead cat, with the focused-on version being what we are physically aware of. The Mind only perceives the wave function; it does not collapse it because we wish to keep the standard mathematics of quantum mechanics intact. So the laws of physics in this dualistic scheme are never suspended or violated. The individual nonphysical Mind associated with you perceives outer physical reality only indirectly, through the state of your brain. The physical brain is a very sophisticated tool or means that the nonphysical Mind uses to interface with the physical world. I would conjecture that this same nonphysical Mind is also the agent for true intentionality. Intention is implemented through the choice of focus of the nonphysical Mind on one particular quantum state of the brain (rather than through the manipulation of the physical world). The associated nonphysical Mind, rather than some innate property of matter, is what distinguishes living from nonliving objects. For some, this nonphysical picture may be hard to swallow. But we emphasize once again that physics implies there are only a few choices for the structure of reality: (1) Perceived reality consists of particles highly unlikely; (2) Reality consists of the collapsed wave function unlikely; and (3) Reality consists of the uncollapsed wave function plus the nonphysical Mind. There are, I believe, no other viable choices (see sec. 7).

5 4. Proof that Awareness Cannot Be Based in the Brain Wave Function Assume that only the wave function, with all its branches, exists; there are no particles, there is no collapse, and there is no nonphysical being that is the source of awareness. Under these circumstances, only the wave function exists, so awareness can only reside in the wave function of the brain. One can prove this is not possible because it violates the probability law. The proof goes as follows: Under the above assumptions, since only the wave function exists, awareness must correspond to some quantum characteristic of the wave function, say the quantum configuration of the prefrontal cortex. One can then show that quantum mechanics implies all versions are aware, regardless of the technical definition of awareness. To see the conflict of this with the probability law, suppose the cat experiment is repeated N times (perhaps with a cat that has many lives, to conserve cats). Then the probability law implies that the number of times one sees a live (dead) cat will be close to N a L 2 (Na D 2 ) where the a s are the coefficients in the wave function, a L [cat alive] + a D [cat dead]. Now when the experiment is run N times, there will be 2 N different versions of the observer, one for each pattern of live and dead cats. But one can show that almost all of those versions will perceive a result which is near N/2 live cats and N/2 dead cats (rather than the N a L 2 live cats and Na D 2 dead cats the probability law predicts). And presumably what we perceive corresponds to one of those almost all versions. Thus the idea that awareness resides in the brain conflicts with the probability law and so it cannot be correct. This implies unamended (no particles, no collapse) quantum mechanics cannot properly account for awareness (of a particular quantum version of reality). So if there actually are no particles or collapse, then that-which-is-aware must not be subject to the laws of quantum mechanics, and hence cannot be based in the physical brain. Note: My (obviously subjective) estimate is that there is no chance that particles exist and less than a 10% chance that collapse occurs, so there is a 90% chance that awareness does not originate in the brain. 5. No Evidence for Particles The almost universally held view is that matter is made up of particles electrons, protons and so on. And there are several experiments which, it is claimed, prove that particles exist. A close examination, however, shows that all the reputed experimental evidence can be explained by quantum mechanics alone. Thus there is no experimental evidence for particles. There are also strong theoretical arguments which imply that the concept of particles cannot contribute to an understanding of the physical universe.

6 Alleged Evidence for Particles. Particlelike Properties Certain properties are ascribed to particles in both classical physics and quantum mechanics mass, energy, momentum, angular momentum (spin), and charge. These properties are the most basic and universally used quantities in physics; they define the concept of a particle. However, it can be mathematically shown, using group representation theory, that the wave function itself possesses or carries these properties. Thus no predictive power is lost if mass, charge and so on are ascribed to the wave function alone. This means these particlelike properties cannot be used as evidence that particles exist. The Photoelectric & Compton Effects The photoelectric effect, in which light scatters off electrons in a metal, led Einstein to conjecture that there were photons particles of light hidden within the lightlike wave functions. But it can be shown that quantum mechanics alone, without photons, gives a correct description of both the photoelectric effect and the Compton effect (which is also a light-electron scattering experiment). Thus these effects cannot be used as evidence for the existence of particles. Localization & Particlelike Trajectories When a spread-out lightlike wave function hits a film emulsion, only one of the film grains will be found to be exposed, even though the lightlike wave function hits thousands of them. This is usually taken to imply that the lightlike wave function has, hidden within it, a particle of light, a photon. In this picture, it is the grain which the photon hits that registers the presence of the photon. However, it can be shown that this localized (single, small grain exposed) detection of a spread-out wave function follows from quantum mechanics alone. Thus localization gives no evidence for the existence of photons. Quantum mechanics alone can also explain the particlelike trajectories observed in cloud and bubble chamber. Discreteness The hallmark of atomic and particle pictures of the physical world is discreteness; matter comes in discrete, localized chunks that carry a definite amount of mass, energy, momentum, spin and charge. One might think that a spread-out wave function could not lead to discreteness. But that is not true; discreteness also occurs when the wave function alone exists. In the case of light, for example, a beam of light contains millions of single-particle photonlike wave functions, each of which acts like (has the properties of) a particle. The same holds for the wave function of the atom; it mimics the properties of an actual, discrete atom. Thus quantum mechanics alone also accounts for discreteness. Difficulties with Constructing a Valid Theory of Particles The Bohm model is a mathematical theory of particles underlying quantum mechanics. The reputed particles follow trajectories derived from the wave function. It seems to satisfy all the requirements on a particle theory, and it is absolutely correct within a certain limited viewpoint. So this appears to put us in the awkward position of arguing against particles when there is a seemingly correct particle theory underlying quantum mechanics. It turns out, however, that the Bohm model is not a challenge to our no-

7 particle hypothesis because it has two hidden assumptions (on the relation between the mathematics to the physics) which disqualify it as a valid theory of particles. A further analysis shows very generally that there are severe problems encountered when one tries to construct any theory of particles, or any other objective form of matter, underlying quantum mechanics. This makes it highly unlikely that a satisfactory theory of particles underlying quantum mechanics can be constructed. The Equations of Quantum Mechanics As a final argument to emphasize the shaky base upon which the concept of particles is built, we note that the equations of quantum mechanics have been extremely successful, correctly predicting the spectra of atoms and small molecules, the chemical properties of the elements, the thermodynamic and electromagnetic properties of solids, the properties of nuclei and elementary particles, and even the life cycles of stars. Further, these equations have never given an incorrect answer. But only the wave functions occur in the equations; there is no mention of particles. Thus the equations upon which all of modern physics is built give no hint that there are particles. Summary of No Particles All the particlelike properties that lead us to suspect the existence of particles mass, energy, momentum, spin, charge, the photoelectric and Compton effects, localization, particlelike trajectories, and discreteness all these can be explained by quantum mechanics alone. Further, the theoretical prospects for constructing a particle theory underlying quantum mechanics are just about zero. Therefore the particle interpretation of quantum mechanics is not currently justifiable and almost certainly not viable. The often referred to wave-particle duality of quantum mechanics is simply a reference to the dual wavelike and particlelike properties of the wave function (which has properties that are different from a classical wave). Note: If string theory turns out to be correct, that would not alter our argument. String theory is still linear and relativistically invariant, and those are the only properties we need. 6. No Evidence For Collapse If the wave function were to collapse down to a single version say the cat dead version shrinks to zero then the world would actually be objective (single-versioned), just as it appears to be. But there are problems with this conjecture. In spite of a number of attempts, no experimental evidence for collapse has been found. To have collapse, there must be coordination between the wave functions for the different versions of reality, and this is impossible in unamended quantum mechanics. So this would represent a radical departure from current theory. There is no known physical mechanism for carrying out the collapse. A theory of collapse would be ad hoc; its only application would be to the collapse problem. A mathematically elegant theory of collapse has been proposed by Ghirardi, Rimini, and Weber, and Pearle. But it has problems: It uses a random force applied by we-know-not-what. It is nonlinear, in violation of linearity, the most basic principle of quantum mechanics.

8 The nonlinear force is simply assumed to have a particular form, so that the conjectured theory will lead to the a i 2 probability law. The force law has two parameters in it, a length and a frequency. The absence of experimentally detectable effects limits the values of these parameters to a narrow range, thereby reducing the odds that the theory is correct. The force law must be assumed, without justification, to be proportional to the mass of the particles involved. It is also frequently supposed that observation causes collapse. The very substantial problem here is that (some aspect of) the observer is given the power to turn off the usual equations of quantum mechanics and replace them with a jump to a single version of reality. Further, if there is no aspect of the observer outside physical reality, there is no rational support for this aesthetically unpleasing suspension of the laws of physics. In summary, there is no encouragement, either experimentally or theoretically, for the idea that the wave function collapses down to just one version. 7. Other Conjectured Interpretations There are a few other interpretations of quantum mechanics besides particles, collapse, and the nonphysical Mind which are worth mentioning. The Everett Many-Worlds or Many-Minds Interpretation This interpretation says that every version of the brain is aware (as in sec. 4). But it makes an unacceptable assumption in its derivation of the probability law (it arbitrarily introduces a weighting factor) and so it cannot be considered a valid interpretation. It is interesting, however, that more than 50 years ago, Everett realized there was no need for the concept of particles. Decoherence Theory Some proponents of this approach claim that it proves collapse occurs within the current laws of quantum mechanics, through the interaction with the environment. But there are situations where the decoherence mechanism cannot produce collapse, so it cannot be considered a valid explanation of why we perceive one particular version of reality. The Copenhagen Interpretation The Copenhagen interpretation for our purposes here says that, because we only directly perceive a macroscopic world, we have no business trying to infer the nature (particles, waves, whatever) of the microscopic world. I strongly disagree. Indirect knowledge particularly experimentally verified mathematical theory can tell us a great deal. 8. Sources of Deep Knowledge As I see it, there are only four sources which we can use to gain deep knowledge of the nature of existence: science; reasoning not based on science; authority (people, books); and personal experience and insight. All of these have drawbacks: current theories in science may be superseded; one s

9 assumptions may be incorrect; authority cannot be fully trusted; and our personal experience is subject to erroneous interpretation. But if we put too much emphasis on the drawbacks, we end up paralyzed in our search. So we pragmatically do the best we can with what is currently available. In this pragmatic sense, I believe the mature science of physics, which has been subject to the uncompromising test of experiment for over 200 years, can offer us valuable insight into the nature of existence.