In the United States and the former Soviet Union, scientists competed to perfect optical phase conjugation—a process that can reverse the motion of a beam of light, causing an image scrambled by an irregular medium (such as frosted glass) to return to its original, undistorted form. They hoped to use reversed light beams to focus laser weapons on enemy missiles.
   At Syracuse University an eminent physicist appeared before a large audience. A professor of religion introduced him as the man who may save the world from the fragmentation of modern Western thinking and bring people to a platform of transcendental wholeness. The physicist then began expounding metaphysical ideas based on physics and Eastern philosophy.
   Although it may seem surprising, the military research work and the university lecture share a common foundation in a fundamental feature of the laws of physics. To understand how this is so, let us first consider optical phase conjugation.
   The application of the technology of optical phase conjugation to “star wars” weapons systems is still in the conceptual stage, but the unscrambling of light that has passed through frosted glass has actually been demonstrated.
   In a typical experiment, light is reflected from an object and passes through frosted glass, causing the light beam to distort in a complicated way. The beam then reflects from a device called a phase conjugate mirror, which reverses the distorted beam and passes it back through the frosted glass. When the light enters an observer’s eye, he perceives a clear, undistorted image of the original object instead of a garbled blur, which he would see if the image were reflected back through the glass by an ordinary mirror.
   As the reflected beam leaves the phase conjugate mirror, it has the curious properties that (l) it encodes information for the original image in a distorted, unrecognizable form, and (2) as time passes, the apparently random distortion is reduced, and the information contained by the beam becomes clearly manifest. Normally we would expect to see just the opposite—a pattern containing meaningful information will gradually degrade until the information is irretrievably lost.
   According to classical physical theory, however, the laws of physical dynamics are reversible, and thus it is possible in theory for any physical process to run backward and recreate an earlier state of affairs from its later end product. This implies that information is never actually lost as a result of physical transformations, and in principle it might be possible to again extract the information from the cosmic energy background. The restoration of a garbled image by a phase conjugate mirror seems to provide an example of this. . . .

Copyright © 2004 by Richard L. Thompson