Consciousness, Physics, and the Holographic Paradigm
Essays and Shadowless Poetry by Alan T. Williams
Part II: Conditional Relativity
Chapter 7: Hologram Theory
Section 1: Dennis Gabor Discovers Holography
In 1947 while working in England to improve the electron microscope, Hungarian electrical engineer Dennis Gabor, recipient of the 1971 Nobel Prize in Physics, invented a method of storing on photographic film a three-dimensional (3-D) image of the information pattern encoded in a beam of light, i.e., in a visible beam of nonmaterial, subatomic, electromagnetic radiation. He coined the word hologram to describe his discovery. Combining the Greek words holos (whole, entire) and gramma (anything written or drawn), an electromagnetic energy hologram is defined as the whole (or entire) 3-D message contained in a beam of light, compared with the partial message obtained in an ordinary two-dimensional (2-D) photograph. Gabor then chose the existing word 'holography' to describe the information storage and retrieval processes that store (cache) a hologram or reconstruct (retrieve) the holographic image.
But static 3-D holographic images do not accurately reflect physical reality just-as-it-is. Human beings live in an energetic, multidimensional spacetime continuum within which dynamic material events and energetic nonmaterial events are ordered in space through time. Thus conventional fixed, or static, 3-D holographic images that remain unchanged in space through time are reconstructed from very low order holograms. Higher order holographic image events that involve dynamic movement or energetic activities which produce changes in material or nonmaterial space through time are reconstructed from energetic holograms having at least four dimensions (4-D).
In 1948 Gabor performed the basic experiments in optical holography (then called "wavefront reconstruction") using incandescent light, but the results were less than satisfactory due to the random phase relationships (the "noise") generated by incandescent light.2 Practical use of Gabor's holographic principles would necessarily await the development of a coherent light source. "Coherent" light means that all of the light emitted by the laser has the same wavelength and is in phase, i.e., there is no difference in the phase relationships of the emitted light. Happily, the invention of the laser (light amplification by stimulated emission of radiation) a decade later produced the needed coherent light source.
In 1958 Charles Townes and his co-workers – including Arthur Schawlow – at Columbia University, New York, and a Russian research group led by Nicolay Gennadiyevich Basov and Aleksandr Mikhailovich Prokhorov at the Lebedev Institute for Physics, Moscow, simultaneously and independently analyzed the possibilities of applying the maser principle (microwave amplification by stimulated emission of radiation) to the optical region of the electromagnetic spectrum. The first operating optical maser, now known as the laser, was constructed by Theodore H. Maiman and was demonstrated at the Hughes Research Laboratories in Malibu, California, May, 1960.
The laser is the indispensable coherent light source that makes contemporary optical holography possible. Among other changes in operating conditions, the step from microwaves to visible light permitted a 105 increase in frequency. Townes, Basov and Prokhorov shared the 1964 Nobel Prize in Physics "for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle". Arthur Schawlow was a co-recipient of the 1981 Nobel Prize in Physics for his "contribution to the development of laser spectroscopy."
Compared to the long day of Plato and Aristotle which has illuminated Western tradition for more than two millennia, hologram theory and holographic principles are only a brief flash of lightning in the cosmos of scientific knowledge as humankind enters the 21st century CE. Nevertheless, this bright flash of holographic lightning may usher in a new day that more clearly illuminates the irreducible foundation of physical reality just-as-it-is.
Conventional optical holograms:
Conventional photography and optical holography are light dependent methods of storing informatiom. Both methods record some of the information contained in the optical region – the visible light region – of the electromagnetic radiation spectrum. Conventional photography records only the intensity of the incident light waves. Optical holography records both the intensity and the phase relationships of the incident light waves. The reconstructed results of the two processes, i.e., a photograph or a hologram, are significantly different.
Light travels through a given medium (air, for example) in a wave-like form. To capture the information encoded in the incident light waves, photographic film with an appropriate emulsion speed records the pattern of light obtained from an object or scene of interest. An ordinary conventional photograph records only the amplitude – the intensity – of the incident light waves. When the photograph is developed, a two-dimensional picture (image) of the object consisting of higher (bright) intensities, lower intensities (shadows) or absence of light can be printed on light-sensitive photographic paper or projected onto a screen (slides, movies). But intensity is only a small part of the information contained in the particular light waves of interest.
Using the coherent light of a laser to illuminate the object, a hologram records the intensity plus the phase relationships of the incident light waves – and perhaps much more information of which we are presently unaware. After the film is developed and coherent laser light is directed through the recorded information at the proper geometric angle, a reversed three-dimensional image containing all the details of the original object is reconstructed in open local space. It should be noted, however, that only part of the information contained in the message represented by a hologram is presently capable of being deciphered using the most sophisticated methods of contemporary scientific understanding.
A diffused hologram has the appearance of random noise and is sometimes compared to a distributed memory:
"One can call it 'ideal Shannon coding' because Claude E. Shannon has shown in his communication theory that the most efficient coding is such that all regularities seem to have disappeared in the signal; it must be 'noiselike'. But where is the information in this chaos? ... It is...a complicated figure, the diffraction pattern of the object, which is repeated at random intervals, but always in the same size and orientation."
Conventional off-axis optical holography requires two light beams: A reference beam and a diffraction beam (also called the object beam). A single laser provides the coherent light beam which is used for both purposes. A beam splitter – an optical device that divides the coherent beam into two parts – is placed directly in the laser beam. One part of the divided coherent beam is then focused directly on the film by strategically placed mirrors and focusing lenses. This unmodified coherent light is called the reference beam. The second part of the divided coherent beam (the diffraction or object beam) is directed onto the object of interest. The modified light waves reflected by the object are then focused on the undeveloped film where they interact with the reference beam. The interaction of the coherent information in the reference beam and the modified information in the diffraction beam creates a unique interference pattern (diffraction pattern) that is recorded (encoded) in the film emulsion. When the developed film is again placed in the path of a coherent light beam at the proper geometric angle, the encoded information is reconstructed and a reversed three-dimensional optical image of the original object is projected into open local space.
Some years after he produced an exact analysis of his hologram theory (1948-51), Dennis Gabor thought the effort to improve the electron microscope might have been twenty years premature. Electron holography actually took nearly fifty years to come of age through the use of the Möllenstedt biprism.
Now, more than fifty years after he first articulated his hologram theory, conventional laser holography, acoustical holography and electron holography all utilize Gabor's holographic principles. And computational holography, a computer synthesized realtime 3-D interactive "holovideo" or interactive virtual reality display of holograms, is a growing area of interest.
Continued in Section 2: Young's Double-Slit Experiment
Reference Notes (Click on the Note number to return to the text):
2 Gabor, Dennis. "Holography, 1948-1971". Science, 177, 1972, 299ff.
Back to Chapter 6, Section 1: From Energy To Mass (under construction)
Last Edit: April 30, 2005.
Comments and suggestions welcome.
This paper is a work in progress.
Copyright © 2001-2005 by Alan T. Williams. All rights reserved.