by Robert DePaolo
This article discusses a possible relationship between the photo electric effect (which deals with the influence of particle wave frequencies on the release of electrons through energy infusion) and the way neutrons are coalesced in fixed circuits to facilitate learning and memory.
As a central theme it is useful to point out that certain features of the natural world attributable to the laws of physics also guide brain function. One such feature is energy transfer. While often difficult to define – because it is something that creates effects rather than being an effect, energy drives everything in nature. Given Einstein’s ideas on the reciprocal relationship between mass (matter) and energy one could argue that it is the sine qua non of existence. One of the more interesting aspects of Einstein’s work derived from the previous work of Maxwell on what came to be known as the photo electric effect. In sense this introduced the world to quantum physics
The Quantum World…
A discussion of Quantum physics can be rather complex, since the topic extends to everything from the measurement of particle momentum and location to the nature of reality itself. As a result, for the purposes of this paper, I will narrow discussion to the ways in which particles and waves interact to produce energy.
There is a long-standing debate in the field of physics regarding the nature of matter at the subatomic level. The prevailing question is whether all elements within the real world are made up of discrete particles (things with distinct parameters – like a enclosed circle or disc with shape and border) or whether the world is most fundamentally comprised of more fluid, less stationary entities called waves.
The argument has persisted over time because when trying to measure/trace both the location and path of particles – as one would with a large scale object moving through space, it has been impossible to determine both where they begin and where they end up. It is as if nature played a trick on her most observant species by creating one set of laws for law-abiding large objects and another for the recalcitrant microcosmic word. A comparison between the large scale and particle world is indicative. For example:
A batter hits a baseball. It travels at a certain speed through the air. It’s mass determines how much gravitational drag will be exerted on it and from that and other factors (such as its exit velocity and wind resistance) its ultimate location can easily be determined. Any decent outfielder can do so without a calculator. The baseball is a discrete object. However in dealing with particles that predictability breaks down. Rather than beginning in one place and ending up in another, particles seem to spread – as though they aren’t really singular entities
Making things even more curious is that as soon as we determine the location of a particle we lose track of its path. One can’t tell where it has gone or if it will end up at a particular destination. By the same token if we are able to determine its path we are unable to determine what was its initial location. It doesn’t seem to “travel” so much as radiate. Experiments involving this phenomenon have come to exemplify what is known as Heisenberg’s Principle of Uncertainty. The inability to trace the path of light with any exactitude has led many physicists to conclude that light is a wave, that the concrete, particle-like assumption of photons (and perhaps all matter) is an illusion.
That would seem to make sense, because while light has been described as wave and particle over time the wave definition would seem to offer a better fit with the uncertainty principle – for the following reason
Waves disperse – they are not discrete. They do not really begin or end anywhere in particular. There is no way to determine the ‘location” of a wave when one tosses a rock into the water. There is just an immediate radiation outward, A wave has only movement, peaks and frequencies. The peak refers to the height of a wave, the frequency pertains to its speed or momentum. Typically, the faster a wave moves the lower its peaks. Because it takes more time for a high peaked wave to rise up and return to a flatter state it is unusual for it to be both extraordinarily high and fast. That is why powerful tidal waves need not be high, in fact are often fairly low. It is their momentum that generates the power that is so destructive. Waves with a lower crest, have that low peak because the speed of momentum mitigates against time-consuming high peak rises and falls.
While confusing, there could be a potential solution to the wave/particle question – even if one assumes light consists of particles (photons)
As Einstein asserted, photons act like particles and as such can also be in compliance with the uncertainty principle. They have no mass and always travel at light speed. At light speed no time elapses in accord with Special Relativity. While the student of physics it taught that light travels at a specific speed (186,00 miles per second) that is our measurement of its speed not the time lapse of the photon itself. The photon does not experience time, which is one reason it does not decay.
Since time does not lapse, neither can space be traversed. With no true sense of space, there cannot be any sense of distance, which means light (photons) can be anywhere at any time. Because it can travel along multiple paths simultaneously measurement by time-bound human tools and the human mind are an uncomfortable scientific juxtaposition of apples and oranges It would seem to be an instance in which the evolution of the human brain adapted to the large scale world simply was not tested and honed by the microscopic elements of nature.
Those explanations would seem reasonable if not for the fact that particles with mass such as electrons also obey the uncertainty principle. That is in part why the particle-wave debate has been so fervent over time. While the wave argument makes sense with respect to massless photons it seems incongruent with the behavior of particles with mass. That has led to various explanations of the particle/ wave conundrum.
Some, such as De Broglie have suggested everything in nature consists of particles and waves in a tandem. In his pilot wave theory he asserted the reason larger bodies have definite locations and do not “super-wander” or radiate is because their mass results in gravity pulling in their wave functions to create location and movement specificity. In other words, gravity (which increases with mass) centralizes…or collapses the wave function. Because more massive objects exert more gravitational force their wave function is shorter – like a very tiny tail rather than a long bushy one. Others, such as Roger Pen rose have suggested everything consists of waves only and that solidity/particularization only occurs when at some point in the wave activity gravity creates a pinpoint of the wave – possibly the crest, giving the illusion of mass, locality and specific movement.
Beyond the peculiar characteristic inherent in uncertainty principle is another feature having to do with how particles interact to produce energy and movement. The classic example of this is seen in the effect of photons on the movement of electrons. As referenced above, Einstein and Maxwell worked on this (the former influenced by the latter). In trying to determine whether matter consists of waves or particles they studied the photon, which, as discussed above has been alternately viewed as a wave and a particle. Einstein proved that it had particle qualities by the following method.
Speed and Bounce Dynamics…
Electrons typically bind to metal. In one experiment designed to release electrons, Einstein flashed photons at a metal sheet and discovered that bombardment of the photons provided energy that enabled the electrons to escape from their “metallic captivity” However this (photo-electric) effect only occurred under specific circumstances. Einstein found that bombarding the metal sheet with photons at a low frequency did not release electrons. Indeed, no matter what volume of low frequency photons was cast on the metal sheet no energy transfer occurred and no electrons were liberated.
That was significant because volume of force does produce cumulative energy in all other aspects of nature. If a baseball is tossed slowly at an aluminum screen it will put some degree of dent in the sheet. While tossing the baseballs with greater force will incur more damage to the screen, some damage will continue to occur even with slower tosses, through an additive affect. If one keeps tossing baseballs at the aluminum sheet damage will add up. It is analogous to the process of erosion.
Einstein discovered that the particle world does not work like that. While endless amounts of photons at low frequencies could not produce the energy required for electron release, even one photon sent to the metal sheet at a high frequency did release electrons.
This signified that the speed of transmission was the real energy producer, that it could create, pinpoint, release and stir up the entire cluster of electrons to create an effect. That process seems to have relevance, either in an analogous or real, functional manner to how the brain operates. One way to discuss such parallels is the following.
Webb’s Reverberating Circuits…
Neuro-psychologist Donald Webb offered an idea of how learning and memory are consolidated. His model was based on the idea of ‘reverberating circuits’. His assumption was that in the learning process neural connections that eventually give rise to fixed associative loops are initially loosely formed with few or no circuit parameters. With time and repetition however certain neural loops become increasingly isolated and distinguished from the surrounding neuronal configurations. In effect, during the learning process, there is electrical energy impingement which stirs things up until particular circuits become fixed and differentiated from surrounding neuronal fields.
This is consistent with information theory tenets (which govern all information systems, including the brain) whereby information attainment always involves the extraction of information from a state of noise – or uncertainty.
One parallel between how neutrons, electrons and photons interact can be seen in the speed/frequency factor. Enhanced speed of the photon produces the energy that releases electrons from metal sheets. Similarly, the enhanced speed of neuronal electrical activity leads to the release-distinction of certain circuits from general brain mass. This is governed by rapid brain waves which occur during the establishment of learning and memory. The comparison is not without substance.
In the the photo-electric effect, the high frequency bombardment on metal is in the blue spectrum (the red is slow) With regard to the brain, the highest frequency wave bombardment on neuronal circuits derives from gamma and beta waves (theta and alpha being slower). Gamma waves are the most rapid and are involved in extremely fast-paced, intense mental activity. Beta waves are a bit slower but high frequency enough to facilitate and enhance focus, attention span and memory. In effect, gamma and beta waves facilitate the “trapping” of neuronal circuits into learning sets and memories
Most relevant to this paper is that, with regard to the photo-electric effect, the high frequency photon bombardment could only release electrons by creating a focal impact. Just as the baseball toss could only make a dent in the metal sheet by impacting at specific sites, so must the photon produce impact locally to release specific electrons from the metal surface. In that sense the word “bombardment” might be less descriptive than the word “circumscribed impact.” In simple terms, energy has to be localized to have an effect, that is, target areas differentially to exert an impact. In many ways that ties the photo-electric effect to the ways in which neuronal clusters are formed in the course of learning and the establishment of memories.
In a neurological context, the establishment of memories is also a narrowing process, where cellular localization must occur. There are several reasons for this. First, if not for a localizing process the noise factor resulting from myriad circuits blending in would make retrieval difficult if not impossible. Second, it would be difficult or impossible for incoming perceptions and associations to gravitate toward relevant neural memory packets (categorical associations) to build on the knowledge base.
So far parallels have been drawn between the photo electric effect and the process of learning and memory consolidation. The question is whether both phenomena derive from the same process. That is, do learning and memory involve particle interactions dependent on speed of transmission, localization and the physical separation of relevant brain circuits from the surround?
It is clear that the electrical activity in the neural transmission process is guided by electrons. The process by which this works appear to be roughly as follows. The initial speed of neural transmission is slow – nerve impulses travel much more (slowly) than do particles in different circumstances. However that is in part due to the volume of cells in brains. Even the brain of a fruit fly has a hundred thousand neurons. In humans, it is more than a million times that. With the initial impingement of neurons into receptor cell bodies transmission is slow due to the noise factor inherent in having to negotiate among many neural circuits prior to memory consolidation. With repetition, however the registration of specific circuits becomes clearer. The pathways between stimulus and response encounter gradually less resistance and become more streamlined. That results in the increased speed of transmission as learning begins to solidify. Once the circuits for a particular learning set or memory are established the transmission is faster and more direct. At that point, the energy focus is intense enough to facilitate retrieval efficiently. In effect, noise is almost completely (but not totally) eliminated.
This gradual reduction of interference/resistance is analogous to what occurs with the flow of particles, and with the premises of the various pilot wave theories, with one exception. In the pilot wave model it is assumed the conversion of a wave into a particle results from the collapse of the wave due to gravity. In other words gravity pulls the variable motion of the waves into a more central location, i.e. gravity provides stability and systemization – as it does for all of the universe.
In the neurological example, it is not gravity per se (though that would have to be involved to some extent) that brings focus to the memory circuit but the enhanced energy that results from an increase in speed of transmission as learning sets become streamlined, and in effect, interference-free.
One obvious flaw in this idea is that photons do not appear to play a role in neural transmission. However electrons have a substantial wave function and behave in ways similar to photons. Moreover, the root of this concept seems intact; because ultimately it attributes both electron release and the development of neural circuit specificity to energy dynamics.
Indeed, it is arguable that the neural model of a photo-electric-like effect is more consonant with the basic laws of physics. For example, consider that photons have no mass. Because of that they exert no force per se. They can bounce off metal sheets all they want without damaging or in any way changing the structure of the surface. If their influence is so vacuous, why the photo-electric effect? Perhaps it is because photons are constantly in motion and movement is the sine qua non of energy. Indeed, one definition of energy has to do with the capacity of any entity to produce work – which requires motion.
In that sense, the distinction between photon and electron dynamics might be less consequential. Both move, both provide energy. Since learning and memory both require a change in energy dynamics in the brain, a narrowing down of impact from the general to the specific (i.e. localization) the comparison between the photo-electric effect and neural activity that produces memory circuits might be valid. All of this is of course, speculation, but if the brain can be considered a component of nature, it is possible that at the most basic level it adheres to the same laws.
Afshar, S.S. (2007) Paradox in Wave-Particle Duality. Foundations of Physics. 37 (2) 295
Cover, T.M. (2006) Information Theory. Wiley-Inter-science 2nd Edition
DeBroglie, Louis (1970) The Reinterpretation of wave mechanics. Foundations of Physics 1 (1) 5-15
DeBroglie, Louis de. (1929) The wave nature of the electron Nobel Lecture
Hebb. D.O. (1961) Brain Mechanics and Learning. London. Oxford University Press
Hilgevoord, Jan. (1996) The Uncertainty Principle for energy and time. American Journal of Physics 64 (12) 1451-1456
Kumar, M. (2011) Quantum: Einstein, Bohr and the Great Debate about the nature of reality. W.W. Norton & Co. p 242
Penrose, R. (1996). On Gravity’s role in quantum state collapse. General Relativity and Gravitation. 28 (5) 581-600\
Towler, M. (2009): DeBroglie-Bohm in Pilot Wave Theory and the foundations of quantum mechanics. Universitty of Cambridge Press.
Veisdal, J. Einstein’s paper 1905 on the photo-electric effect. Einstein Essays. August 2019