Guest EditorialI have been a SETI league member for several years, because I find the general philosophy of SETI fascinating. Now that I have retired, I plan on devoting more time and resources to establishing a Project Argus receiving station. While gathering my thoughts on how to approach this project, I began to think about other possibilities of intelligent communication within the electromagnetic spectrum.
The rationale behind the "water hole" region for electromagnetic communication is convincing and has a sound basis that has been developed around our present understanding of physics and the universe. The water hole is defined as a band of frequencies between 1420 MHz and 1670 MHz. 1420 MHz is one of several "magic frequencies" much favored for SETI work. The reason for this is, that it is the natural frequency emitted by neutral hydrogen. Hydrogen line radiation is found throughout the known universe. It is kind of a cosmic beacon. But perhaps not the only one.
In 1967, I was working on a laser project at the Bendix Research Laboratories, a process that would produce coherent, vacuum ultra-violet light. The physics involved is basically the same as that employed in today's modern gas lasers. But this process generated light in the UV spectrum at a wavelength of 90 nanometers, far above the visible spectrum, which peaks in the blue green at 520 nanometers. This was "cutting edge" technology at the time, and required a process know as "single photon counting" to detect the ultra-violet light.
The term vacuum ultra-violet reefers to wavelengths of light that can only exist under ultra high vacuum conditions in the laboratory or in the vacuum of space. The detector itself was, by today's standards, crude. In fact, the detector, known as a "channeltron", was used to detect high-energy particles and UV photons. An experimental package containing an array of these detectors was placed on the lunar surface during the second moon walk. The package was designed to detect particles such as cosmic and gamma rays, as well as high-energy neutrons emitted from the sun's surface and other cosmic sources.
Transmission of information using short bursts of modulated ultra-violet light would be very efficient, assuming very efficient detectors and light sources were available. The data rate and bandwidth would be almost infinite at these wavelengths. As an example, currently data is transferred over the Internet through fiber-optic cable and microwaves. The information is contained in short packets of digital data used to modulated light as well as microwaves. We are fast moving in the direction of optical communications, and SETI should follow the same trend.
You may recall the Space Shuttle mission a few years back devoted to the installation of a fix for the optics aboard the Hubble space telescope. During a live video broadcast from the Shuttle, some unexplained streaks of light appeared in the background. The streaks were moving at extremely high speeds and abruptly changed direction as they went. In addition, intensely bright flashes could be seen in and around the fast moving objects. NASA speculated we were seeing ice crystals streaming back from the orbiter.
Perhaps we were. Perhaps not. Might the fast moving objects have been some sort of space probes, and these intense, short flashes of light have actually been some form of communication between these fast moving objects? Regardless of the evolutionary process involved in producing an extra-terrestrial intelligence, communication between entities would most likely take place somewhere within the electromagnetic spectrum. Otherwise, why are we going to all this trouble to listen?
If (as has been widely suggested) interstellar space probes do exist, then it stands to reason that they must carry some means of communication. There are many ideas on what form this communication may take. As an example, Leon T. Darcy discussed his theory in the Autumn 1999 issue of SearchLites. Two other interesting articles "The Cosmic Light No One Can Explain" and "Watching for a Signal from E.T.", appeared in the August 31, 1999 issue of Time magazine,. This suggests that many others are giving serious thought to SETI. We should now be considering technologies just beyond the cutting edge. They may represent the future of interstellar communications.
New satellites are presently under development. They will be able to view x-ray as well as ultra-violet emission sources beyond the attenuation and absorption effects of Earth's atmosphere. ETI may already be trying to communicate; we just may not be listing at the right spot on the electromagnetic dial.
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