Rethinking the Process of Vision

I have received a number of requests to summarize this explanation of the vision process. This is another attempt to do so / GCH

The initial text here uses  two figures excerpted from the original paper (available on webpage) and forms the fundamental basis for the explanation. All follows from this argument.

The first figure attributed to Osterberg recounting the distribution of cones and rods on the retinal surface is referenced in countless textbooks on vision.  There can be no doubt that these measurements have been accepted by vision science. One notes (although it is not clear in the drawing)  that most of the cone receptors, in fact greater than 99%, are contained in only one degree of retinal angle.  This small region is  termed the fovea.  As one proceeds to retinal angles beyond one degree it is seen that rod receptors are introduced  into the dense (hexagonally packed) array of cones in a statistically distributed manner. The accepted model states that it is the array of cone receptors functions to “detect color”.  It has been historically assumed that, in agreement with the known trichromicity of vision, there must be three “classes” of color sensitive cones - commonly termed as red, green and blue sensitive. Now, keep in mind that >99% of all of the cones reside in the small central foveal region - within the narrow one degree retinal angle.  Vision science goes on from here to assume from that the retina represents the intensity-only sensitive image plane of the optics of the eye. This is the plane where film is located in a camera. To imagine how these cones might form an image they must display some spatial order as in the regular array of RGB triads or stripes on a television screen  or in the imaging chips used in digital cameras. But….none of this appears on the retina! The proposed RGB sensitive cones are haphazardly distributed with no discernible order…and, moreover, the blue or “B” sensitive cones have a difficult time making an appearance at all !

I believe that this describes the paradigm that has evolved in vision science . Even on the face of it, is in my view totally irrational.

It is the accepted Osterberg data that forms the fundamental basis for my explanation.

A logical interpretation of  Osterberg’s  measurement  in this work proposes that  it  is the distribution of receptor appositions that defines sites where light  wavelengths interact on the retinal surface. It is not “photons interacting with pigment molecules within receptors” but rather light interacting as  the wave of clasical physics interacting in antenna fashon between adjacent receptors. As presented in the original paper, a simple counting (i.e., cone-cone, cone-rod, rod-rod) of these appositions as a function of retinal angle reveals a diffraction the light sensitive surface that underlies the trichromicity of vision. This, in turn, reveals that the retina is actually a diffractive  surface forming the  Fourier (or focal) plane of the optics of the eye and not the intensity-only or “camera film” surface that has for so long been presumed.

This is the fundamental essence of all that  follows!

The retina of the eye, and specifically the plane of retinal outer segments, is seen to be composed of an array of more than 130 million logically spaced light detection elements (or pixels)  that function to translate incident electromagnetic wave radiation into quantized electron particles.  These elements function in the near-field ( i.e., of dimensions smaller than light wavelength) and in times as short as femtoseconds ( 10-15 sec) . The quantized electrons encode the electrical information necessary to form the visual image. The historically defined cone and rod receptors are seen to function as generic structural elements that function  to provide the required spacing between adjacent receptors. The ratio of the diameters of these two sizes of receptors actually corresponds to the visual band, i.e., the ratio of  -1.8:1 corresponding to the 700-400 nanometer visible band. We must stop thinking of  receptors as cones and rods with different functions and realize that they represent simply two  sizes of  generic light conversion elements.

The lateral spacing of this nanowire array is determined by a simple geometric rule that selects  three wavelengths from the broader electromagnetic spectrum for detection in the vision process. These are the same three wavelengths that have historically  been termed primary that underlie the correctly understood trichromicity of vision

This geometric  rule derived from the retina states that: an admixture of circles of two diameters defines three center-to-center wavelength-determining dimensions with the ratio of these two diameters defining the detected bandwidth.

Further, these three wavelengths are pre-selected  by the light refractive chromatic aberrration of the structure of the evolved eye and focused onto the retina. This refraction has been historically and improperly termed an aberration but it is not an aberration at all but is fundamental to the visual image formation process.

In the largest sense then it then becomes clear that the true nature of the vision process is an objectification of the basic laws of the refraction of light and that the biological morphology of the retina evolved from simple and well understood molecular (chemical/polar lipid) self-organization mechanisms.  Paraphrasing LaPlace  “There is no need for a creationism hypothesis”.

The three wavelengths detected by the retina  have  historically been correctly defined as primary but  improperly termed as colors. Early vision science discerned the  trichromicity of vision  but from that point picked the wrong model to explain it.

Thus, at the basis of evolved biological vision is a nanostructure that geometrically selects three wavelengths from the broader electromagnetic spectrum and translates these into quantized electronic information that is used to form the visual image.

The nanostructure of the retina  evolved to detect light as an electromagnetic wave with the quantum transition to electron particle occurring at the point of retinal outer segments. The result instead of imagining that  “a photon interacts…” should properly be termed more generally that a  quantized interaction occurs.  The traditionally used construction that photons interact with pigment molecules within retinal receptors was always inaccurate.  And further, it is not and never was the case that “photons go from place to place”.

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For a discussion of the history of the concept of a photon read the paper “Anti-photon” by Nobelist Willis Lamb(Appl.Phys, B 77-84, 1995)

From  the abstract of that paper.

“It should be apparent from the title of this article that the author does not like the use of the word “photon”, which dates from 1926. In his view, there is no such thing as a photon. Only a comedy of errors and historical accidents led to its popularity among physicists and optical scientists……”

So there!!!

But Richard Feynman believed in photons !  …  from his “QED” p.15:

“I want to emphasize that light comes in this form - particles. It is very important to know that light behaves like particles, especially for those of you who have not gone to school. where you were probably told something about light behaving like waves. I’m telling the way it does behave - like particles.” (emphasis from F.)

This is like being told that there is no Santa Claus!

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Further, it must be emphasized that the individual light detection centers of the retinal array have dimensions smaller than light wavelength (i.e., they function in what is termed in physics the near field) and in a time scale of femtoseconds (10^-15 seconds). These centers therefore serve to effect a fundamental quantized spacetime translation from wave to particle.

Following the initial light absorption process, energy is transported laterally (i.e., parallel to the plane of the retinal surface) along the lipid membrane that forms the structure of the thylakoid disks within receptors. This energy transport occurs via a phononic  (or, as I propose, lossless solitonic ) mechanism that serves to thermalize the absorbed energy  slowing the process down to human nervous system proportions, i.e., near millisecond (10^-3 seconds). What has been termed the millisecond reaction time of the eye was always actually the reaction time of the human nervous system and not the eye itself.

Thus, the traditional morphological distinction between cones and rods can be finally understood. The function of the opsin protein moiety of the rhodopsin complex contained within receptors is actually structural with the purpose of it’s various perturbations being to effect the variable wavelength-defining spacing of the retinal array. Also finally explained is the, what has been termed,  anomalous, dichroism of the rhodopsin light-accepting complex. We can now make sense of the laterally directed orientation of this molecular complex.

The incorrect idea that “cones detect color” and “rods detect black and white” quoted in  every textbook on vision can now discarded. Use of the terms “primary” (as  noted above) and “color” are now understood. The retina geometrically detects three primary wavelengths with the term “color” reserved to describe the synthesis of hues from these wavelengths as elegantly described by Edwin Land - when is someone going to realize this! Not unimportant in this regard is the finding of this work that the exact midpoint (near 550 nanometer) of the visual band  that vision uses  for “Land color synthesis” is geometrically determined. In one stroke a large part of the image forming logic used by the eye in vision is explained.

In summary, it can be seen that the “first stage” of the vision process functions in the realm of quantum physics with all that this portends.

One then imagines that we humans “peer out”  into the broad electromagnetic spectrum that surrounds us through three narrow biologically evolved wavelength filters gathering information from that as yet only dimly understood regime of quantum physics - but we can now be sure that this is the case!.

The future of our understanding of the vision process seems  linked to the domain of quantum physics.

GCH

Ojai, CA

The nanostructure  that forms the surface of retinal outer segments  functions to absorb light as a classical electromagnetic wave between receptors  while simultaneously translating the absorbed energy  into a quantized electron particle in the mass of the receptor itself.  This fundamental interaction is described  in quantum  physics as occurring between quantized light particles (photons) and  single atoms. 

The biologically evolved nanostructure of the retina, however,  is structured to perform  two additional functions. The first directs the absorbed wave energy orthogonally to quantum-confined electron sites  These sites are the retinal/rhodopsin molecular complexes that have been sohown to have the correct dichroic orientation for accepting the absorbed energy from this direction. The second function involves  the  energy transfer process that  temporally “slows down”  or thermalizes  the interaction to the final, human nervous system useful, time domain. This involves a transition from    ~10^-15 seconds (femtosecond) to ~10^-3 seconds (millisecond).  I have proposed that this  transfer of energy process involves a solitonic  (lossless) mechanism in the membraneous lipid structure of the thylakoid disks that comprise the body of retinal receptors.

In overview then, the retina evolved to detect light as a wave in a two dimensional array of quantized electron sites  that  translate the absorbed energy into what  becomes  the visual image. This information in the quantum domain is subsequently transformed in time to human nervous system scale by the remainder of the retinal structure and transmitted coherently through the optic nerve to the visual centers of the  brain.

GCH

10.05.08

Ojai, CA

In this explanation, the EXACT MIDPOINT of the visible band at 550 nanometers is spatially defined on the retinal surface by a geometrical rule .SIMPLE GEOMETRY IS STRUCTURALLY RELATED TO, AND PRECISELY DEFINES, THE WAVELENGTH OF LIGHT.

This region on the retina is the point where sufficient rods are present to completely surround individual cones in an octagonal symmetry. This point is at 7-8 degrees of retinal eccentricity (degrees from the foveal center).

What this means:

a.) Geometrical space and the electromagnetic wavelength of light are related in a biological system to produce an effect – color vision!.

b.) The exact middle of the visual band at 550 nanometers is defined for use as a wavelength reference for subsequent color processing. This provides the basis for the prescient finding of Edwin Land over fifty years ago!

“…we have learned that the eye must have a fantastic mechanism for finding a balance point within a band of wavelengths” Edwin Land

c.) It provides the basis for the first understanding of the color constancy of vision.

d.) It is the fundamental reason why we all see colors the same way! To quote Einstein again: “..all is geometry”.

For details PLEASE read the work!

GCH

Ojai,CA

To anyone following this work it will be clear that I believe that the primary process (or processes) of vision – interaction of light with the nanostructure formed by retinal outer segments – occurs in the spatial near field and in the femtosecond (10^-15 sec) time domain. That, what is termed the primary chemical event in the vision process – isomerization of the rhodopsin chromophore within the body of the retinal receptor - occurs in femtoseconds has been known since the late 1980’s. A reference chosen from many:

“The First Step in Vision: Femtosecond Isomerization of Rhodopsin” RW Schoenlein, LA Peteanu, RA Mathies, and CV Shank Science, Vol 254, Issue 5030, 412-415, (1991)

Lawrence Berkeley Laboratory, University of California, Berkeley 94720.

ABSTRACT

“The kinetics of the primary event in vision have been resolved with the use of femtosecond optical measurement techniques. The 11-cis retinal prosthetic group of rhodopsin is excited with a 35-femtosecond pump pulse at 500 nanometers, and the transient changes in absorption are measured between 450 and 580 nanometers with a 10-femtosecond probe pulse. Within 200 femtoseconds, an increased absorption is observed between 540 and 580 nanometers, indicating the formation of photoproduct on this time scale. These measurements demonstrate that the first step in vision, the 11-cis—-11-trans torsional isomerization of the rhodopsin chromophore, is essentially complete in only 200 femtoseconds.” (underline is mine).

Now to define this retinal nanostructure – forget the idea of cones and rods and view it abstractly as a two dimensional array of quantum confined electrons in the near field of light. We are viewing then, in essence, a quantum structure!

As we enter the nanostructural era, and our ability to make measurements in the femtosecond time domain matures, we might expect to find new processes – quantum processes - at work in processing of visual information.

Even now such new experimental results are being reported corroborating the . A recent paper by University of California investigators is one such result. The reference:

”Evidence for Wavelike Energy Transfer Through Quantum Coherence in Photosynthetic Systems” , Engel G.S. et al,. Nature, Volume 446, Issue 7137, pp. 782-786 (2007)

PORTIONS OF ABSTRACT:

“Photosynthetic complexes are exquisitely tuned to capture solar light efficiently, and then transmit the excitation energy to reaction centres, where long term energy storage is initiated. The energy transfer mechanism is often described by semiclassical models that invoke `hopping’ of excited-state populations along discrete energy levels……….

….But the intricate dynamics of quantum coherence, which has no classical analogue, was largely neglected in the analyses-even though electronic energy transfer involving oscillatory populations of donors and acceptors was first discussed more than 70 years ago, and electronic quantum beats arising from quantum coherence in photosynthetic complexes have been predicted and indirectly observed. Here we extend previous two-dimensional electronic spectroscopy investigations of the FMO bacteriochlorophyll complex, and obtain direct evidence for remarkably long-lived electronic quantum coherence playing an important part in energy transfer processes within this system. The quantum coherence manifests itself in characteristic, directly observable quantum beating signals among the excitons within the Chlorobium tepidum FMO complex at 77K. This wavelike characteristic of the energy transfer within the photosynthetic complex can explain its extreme efficiency, in that it allows the complexes to sample vast areas of phase space to find the most efficient path.”

(I would not agree with the last sentence that I have underlined… “allows the complexes to sample”….NO!…. / GCH )

The fundamental point of this work I believe is that a new phenomenon – quantum coherence- has been introduced into, and shown to be operative in, the light energy absorption process. It seems not too much of a leap to see how this mechanism might be at work in light interaction with the quantum retinal nanostructure as noted above.

Entirely new mechanisms at work in the femtosecond time domain with all that this portends for the capability for processing information!

A note – I have proposed and shown specifically how – the nanostructural retina is deployed in the photosynthetic apparatus of the world of plants and algae. The photoreceptive apparati of biological vision and plant photosynthesis use the same fundamental nanostructural principle.

Think !!!!

GCH

11.25.08

“Don’t worry about people stealing your ideas. If your ideas are any good, you’ll have to ram them down people’s throats.”

(A NOTE: If it is not obvious, I do not consider these Comments  in any way  to be finished technical papers. The are meant only as updated thoughts  that occur to me that follow from the insight of my explanation for light interaction with the retina.. I would hope that they  might elicit reasoned discussion and/or argument. GCH)

The eye teaches that it is not photons that are detected but rather the wave nature of light.  Photoelectrons.generated within the absorbing mass are the product of this interaction. The nanostructural array formed by retinal outer segments absorbs light as the electromagnetic wave and transduces the absorbed energy at this point into quantized, i.e., particle, electrons..

I have proposed that the retina of the eye is an array (a nanostructure) of more than 130 million logically spaced light interactive devices that function to translate incident electromagnetic wave radiation into quantized electron particles that encode the visual image information. These devices function in the near field (oi.e., of d spatial imensions smaller than light wavelength) and in at least the femtosecond (10^-15 sec) time domain.

These small space and time dimensionalities define the regime of quantum physics. The initial (”first stage”) interaction of light with the retina involves quantum physics.

The individual light interactive sites (or devices) of the retina are each composed of two separate spaces: 1.) a variably dimensioned space that controls the wavelength of light absorption and, 2.) a space of smaller, fixed, material determined, dimension that “quantum confines” an electron (according roughly to the “electron-in-box” approximation of physics). The electron then constitutes the “absorbing mass”.

The generality of the devices of the retina is that they accept light as a wave and transfer the absorbed energy (laterally via an evanescent wave as I describe) to a “particle” electron that is used in subsequent electronic image formation processes.

Thus, it is a retinal nanostructure that is involved in light absorption.

This surface entails the same light absorption physics as the photoelectric surface studied by Einstein with the difference being that the particle electron is absorbed in the structure for subsequent use rather than being emitted into a vacuum.

Regarding Einstein’s interpretation of the photoelectric effect, a quote from Hunter and Alexandrescu “Photons in the Photo-Electric Effect”, p.2,:

“..of the conclusion of Einsteins’s ‘photo-electric’ paper of 1905 (ref) that the photo-electric effect is only understandable if the energy in a beam of light is concentrated in localized packets each having energy hv (now called photons) whereas it is not understandable in terms of the model of light as a plane wave having uniform intensity over the surface of the photo-emissive surface”.

Is it possible that light in the PE effect was absorbed as a wave and the “quantization” that Einstein correctly discerned occurred in the absorbing mass?

(One must note here that E. could not have had any notion of the specifics of a nanostructure being involved in the PE light interaction process. Even today the precise physics of photosurfaces are not well understood)

Did Einstein and subsequent physics make the mistake of “quantizing both sides” of the interaction (photon and electron) and therefore create the insoluble “wave/particle” dilemma?

Thus, from the teaching of the retina of the eye there are no such entities as light photons. The wave nature of light prevails in the universe with quantization occurring in the “detector” or the absorbing mass.

There is much more to support this claim I will refer to the writings of Richard Feynman:

F. after correctly noting that the “most fundamental interaction in nature was between the photon and the electron”, proceeded to make the same fatal error of “quantizing both sides” of this interaction.

I will begin by discussing of the characteristics of the light detection referenced by F. – the vacuum photomuliplier tube (PMT)  F. used this device and specifically its ability to detect “single photons” as the basis for his entire thought process.

I WILL EMPHASIZE HERE THAT I BELIEVE THE TERM “QUANTIZED INTERACTION” SHOULD BE USED INSTEAD OF “SINGLE PHOTON”. AND FURTHER, THE PMT DOES NOT DETECT EITHER –THE DETECTOR UNDER CERTAIN CIRCUMSTANCES IS ABLE TO DETECT SINGLE PHOTOELECTRONS.

From F’s treatise “QED The Strange Theory of Light and Matter”” (Princeton University Press, 1985):

(I must assume his statements in this book reflect and are not at variance with his deeper thinking).

From p.15:

“….where you were probably told something about light behaving as waves. I’m telling you the way it does behave – like particles” (the emphasis is F’s).

And a further quote from the same page:

“You might say that it’s just the photomultiplier that detects light as particles, but no, every instrument that has been designed to be sensitive enough to detect weak light has always ended up discovering the same thing: that light is made of particles” (this time the emphasis mine).

And yet another quote (pp.36, 37):

“…but the wave theory cannot explain how the detector makes equally loud clicks as the light gets dimmer”.

It is important to note that F. in his QED exposition does not generally differentiate between “weak light detection” and “single photon” detection and often uses these terms interchangeably.

Now….F’s use of the photomultiplier as a fundamental example of a “single photon” detector requires elaboration. A PMT is a vacuum tube device containing a photosurface (PS) applied to the inside light entrance surface of the glass envelope. Incident light releases photoelectrons into the vacuum where they are accelerated by a mechanical dynode or similar structure with the amplified signal reaching an anode output.

What has become to be termed the “single photon response” of the PMT was discovered only some years ago (in the 1960’s?) quite by surprise. What was really discovered, however, was that single electron events could be discerned (“counted”) at the output of the device. How this discovery was made is an interesting story and I believe that I might even have attended an IEEE Nuclear Science symposium in Washington, DC where this was first reported. I remember hearing this paper and sensing that it was truly important – single electrons could be detected at room temperature!

In essence, what was found was that in certain PMT’s an peak unexpectedly appeared on the low energy electronic “noise tail” at the electrical output of the detector. It could readily be deduced from the location of the peak that the events that it comprised: 1.)events that had undergone the highest amplification and, 2.) that this certainly would represent events that were initiated at the entrance photosurface, i.e., from one spatial location in the PMT structure. Importantly, events comprising the peak (broadened by the electronic noise of the PMT) would all have the same amplitude. All single photoelectron events had the same amplitude at the output of the device much as the output of a Geiger counter in nuclear particle detection. This becomes important in what follows.

In terming this output to be caused by single photons F. would have to assume that a 1:1 correspondence existed between the incidence of a single photon and the release of a single electron into the vacuum of the PMT. Einstein made the same assumption. Quoting from Eisberg and Resnick (Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles” (John Wiley, 1974), p.35:

“He (E) also assumed that in the phbtoelectric process one photon is completely absorbed by one electron in the photocathode”

To my knowledge, and following the significant amount of study applied to the study of the physics of photosurfaces, such a 1:1 correspondence has never been demonstrated either theoretically or experimentally. Quite the contrary, there seemed to be an “anomalous” yield of single electrons released to the “number of incident photons”. As I remember (and I stand to be corrected) the best that could be discerned was that a statistical number of photons (30?) was required to release of a single photoelectron.

In the light of this teaching of the nanostructural aspects of light interaction, what is the physical situation here? All that is known is that this interaction occurs in an atomically thick chemical compound layer that had been vacuum deposited on the inside surface of the light entrance glass thickness of the PMT envelope. A primary requirement is that the compound/surface have a low work function, i.e., a propensity for releasing an electron. As I remember, cesium compounds are used but there are others. There was certainly no understanding of a mechanism or mechanisms involved in a 1:1 correspondence between a single incident photon and the release of a single electron!

I would add, and will discuss in more detail shortly, that the constant signal output from a PMT corresponding to single photoelectron events tends to explain one of Einstein’s conclusions about the PE effect.

I would propose that ALL detectors that reach the sensitivity level discerning single quantized events (SUCH AS THE RETINA) produce a “standard pulse height output”.

In the spirit of this communication, this means that this detector senses some minimum amount of light wave energy that is solely determined by the DETECTOR.

Quantization of electromagnetic energy occurs at the absorbing detector!

I will repeat a statement made earlier that we – at least through our organ of vision – proceed through a universal sea of electromagnetic energy using three geometrically-defined nanostructural “antennas” that are spatio-temporally tuned to the three wavelengths that we term “primary” with this absorption being quantized in the light detection process.

Questions…?????

GCH

11.22.08

Ojai,CA.