Shufflebrain

Phase, as I have said, is a sizeless entity -- sizeless in the sense that we can't measure it with a yardstick or weigh it on a scale. We speak of phase in terms of angles or their equivalents, or in terms of time. And to create an angle, or to specify it, we need more than a single entity. Phase demands a reference, something to compare it with. Because phase is relative, we cannot treat it, or even conceptualize it, as an absolute.

We can appreciate both the nature of phase and the problems in dealing with it by looking at the face of a clock. The revolutions of the hands around the dial describe the phase of the hour of the AM or PM. The hands move at different rates and exhibit different phases. Yet the phase difference--the relative phase--converts the seemingly abstract, invisible, untouchable, ever-beginning, never-ending dimension, time, into our time--people time! Five-thirty is the phase of the morning when we must crawl out of the sleeping bag and milk the goat. Four-fifteen is the phase of the afternoon when children will be getting off the school bus expecting warm cookies and cold orange juice. Phase on the clock has the same theoretical meaning as it does on a wavy surface. Thus relative wave phase is a part of our everyday lives.

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In an optical hologram, such as the one my students and I experienced, the encoded message exists in a special kind of shadow, the interference pattern--alternating zones of light and dark. The densities of the shadows depend on the intensity of the light, and carry the information about amplitude. How rapidly the shadows change from light to dark depends on relative phase, and thus carries the phase code. As I mentioned earlier, objects warp light; they warp amplitude and phase. The warp, in turn, creates the shadows. In fact, the shadows are transformations of the wave's phase and amplitude warps to a kind of mathematical warp in the photographic plate. When the correct decoding beam passes through those shadows, the shadows warp beam's waves. The shadows force into the decoding beam the very phase and amplitude changes that created them in the first place. And when the decoding beam forms an image, it is, by every physical standard, completely regenerating the scene as an optical phenomenon, even though the objects may be gone.

What about photographs? They, and all conventional pictures, capture intensities of light from a scene. Photographs encode information about amplitude but not phase.

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Optical holograms encode for amplitude as well as for phase variations in the scene. The basic reason for this has to do with the nature of light, with the waves' attainment of maximum speed. But other kinds of waves also make holograms. An acoustical holographer, Alexander Metherell, some years ago had a hunch that phase was really the generic essence of the hologram. Of course we can't have phase all by itself, except in the abstract, which Metherell , of course knew. But he wondered if he might assume just one amplitude--create a constant background din--and then encode the message strictly with phase variations. It worked. And Metherell went on the demonstrate his point with the phase-only holograms I referred to earlier.

I mention phase-only holograms at this juncture to make a point about hologramic mind. The frequencies and energy levels in the nervous system do not remotely approach those of light. For this reason, we can't make a literal comparison between optical and neural holograms, at least not in using hologramic theory. Also, because of phase-only holograms, amplitude variations would not play a necessary and indispensable role in the storage of information in the brain. Phase is the essence of hologramic mind!

Before I supply more background on holograms, per se, let me raise still another important preliminary question. What do we actually mean when we use the word wave ? Let's take an introspective look.

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