An explanation of "Practical Reason" or "Intuition" using LASER holography as an analogy.

First published 1991 - the idea dates from 1974.

What I would like to discuss is the similarity between the property we usually call intuition (what Kant called "pure practical reason") and some of the properties of reflective LASER holograms.

I'll explain lots of assumptions, so be prepared to skip the odd paragraph if it's "old hat".

What is a LASER ? It stands for Light Amplification by Stimulated Emission of Radiation. What it does is produce a beam of coherent light (of some frequency). It is coherence which is the key property.

Coherence means that all of the waves of light are going up and down together - If you put a plane at right angles to the LASER light beam, then the light going through it will all have the same wave form (at one instant all crests, a short time later all troughs). This is the key to holography, because it allows the development of meaningful interference patterns.

[Note from 1997 - all reference to waves in this article ought now to be replaced by reference to the phase of the spin property of photons - see articles by John Murphy - but that is another story].

Next the physical apparatus. You need a LASER light source, a prism with which to split the beam, a mirror, a photographic plate, and (or course) the object to be holographed.

It is arranged something like this :-

                         Prism                         Mirror
LASER] ---------------------|\-----------------------------\
                            |               ^              |
                            |       <- Coherent Light ->   |
                            |                              |
      Photographic Plate -> \---------------------------Object
                                ^Reflected (incoherent light).

Interference is the property of waves which allows them to sum together. Thus two waves in harmony appear like one big wave (twice the size), while two which are half a wavelength out of phase cancel each other out (and there appears to be no light there) - This is the same effect that kills ships in violent cyclones - when waves approach from many angles at once.

The pattern which is formed in the photographic plate is an interference pattern.

At each point (in three dimensions) the intensity of photographic development is proportional to the sum of all possible (at least in theory - a large number in practice) light beams from all possible points on the object, to the beam which arrives directly from the LASER prism.

Two factors affect the sum at a point - the path length of the beam (and hence the phase relationship - how far apart on the wave cycle the two paths are); and the intensity of the reflection.

The interference pattern so formed is meaningless to the unaided human eye - it just looks like a weird pattern of blobs in the plate (in three dimensions - even a thin photographic plate is many molecules thick).

To make sense of it, you have to reverse the process. You need only develop the plate, place another mirror where the photographic plate had been, and move the developed plate a little towards where the object was, and turn it at right angles to the beam. Now remove the object, and the image of the object remains, created by the interference pattern between the two beams.


Now to the interesting stuff.

That plate has two very interesting properties.

What would you think would happen to the image if we cut the plate in half ?

It would drop in resolution. Because all points in the plate are the result of an interaction with all points on the object, the smallest part of the plate contains the image of the whole (any Zen enthusiasts about ?).

If our object had been a cube, then cutting in half would have rounded the edges, and blurred the distinction between cube and sphere; but it could still be interpreted as cube with a little imagination.


Second property.

If we take away all of the mirrors and prism, and have just LASER, plate, and our object - we can demonstrate the really mind bending property.

Now arrange the object with a lot of different objects, and pass the LASER beam through the plate. What happens ?

Interested ? <g> (means Grin)

The objects are illuminated in proportion to their similarity to the original object.

So what ? (you may ask?)

If this technique is developed to store and retrieve interference patterns of abstract models (or concrete objects), then it has the potential to scan all available information almost simultaneous (no more indexing or serial scanning).

To make this work you need a pattern recognition and construction system (neural net) to construct "concept primitives". You also need a means of "extracting and exploring" the "brightspots" in the knowledge base.

I am uncertain of all of the mechanics of these secondary processes; but it does appear to me to be the most rational model to explain how and why we have come into existence.

There's one more property of ye olde holograph that needs specific exploration to tie things together a bit more clearly.

If you take a number of holographic pictures of similar things (let's use the example of balls). If you had no knowledge of what "ball" was. How could you figure it out. Holograhpically, you take a pic every time you hear the word ball. Then you display the results, but instead of doing it one pic' at a time, you "gang" together all of your pic's. The image which forms is the "essence of the concept of ball" as distilled from available information. If you have been shown a good selection of balls this will include primarily the notion of a spheroid. But if all the balls you've seen so far were red, then redness is also likely to be an attribute of ball.

Striking out on a bit of a tangent, this is why communication is difficult between people from widely different backgrounds, particularly if their experience sets are rather narrow. The "sets of attributes" which they associate with particular words may be very different - for the simple mechanical reason of their differing experiences.

The way I envisage the process working - say using the example of speech - is that a sound is heard, that sound (in context) is (as holograph) played across all stored information, all "bright spots" are then retrieved, "ganged" together, and the resulting "image" is the notion which our consciousness receives.

Where I get the idea that "reason is an artifact of holographic storage and retrieval of information" is in the ability of information stored as an interference pattern to be integrated in the manner in which it can. The ability of this simple mechanical process to "distill the essence" out of anything.

Intuition, as I see it, is the power of this holographic process to "distill out" a pattern from a set of observations, where previously no such conscious awareness existed. It is a very powerful tool. Where the knowledge base was limited (ie without any knowledge of a mechanical process which could produce this effect) then such an event could well appear "magical" or "God given".

The extreme amounts of neural activity associated with an event of this kind, which is of large magnitude, would be in the form of a "neural storm". The immediate perceptual effects would be "overload" (blinding light, the sound of rushing wind or water, heat ...) All of the things classically associated with great "intuitions" - as in the cartoon (lightbulb appears above man's head).

Hope this makes as much sense to you as it does to me. But I may have missed something out. I've been thinking this way since '74, since, as a second year biochem student, I attended an international conference on holography which happened to be held on our campus. It all seemed so simple and natural, I found it hard to see why others couldn't see it. I hope I've got better at explaining it over the years.

Here is a series of links to another discussion which in part touches upon the use of holograms, 2nd ref, 3rd ref, 4th ref, and 5th ref.

Please send any comments or criticisms to: Ted