Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization
© 1975-1979, 2008 Robert A. Freitas Jr. All Rights Reserved.
Robert A. Freitas Jr., Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization, First Edition, Xenology Research Institute, Sacramento, CA, 1979; http://www.xenology.info/Xeno.htm
24.1 The Cosmic Miracle
Before any two sentient races may converse across the interstellar void, they first must have each other’s attention. Each civilization must know who or what to look for, where and when to look, and how, technologically, to communicate. This is the problem of "acquisition." Each party must know that the other exists.
A number of interesting acquisition techniques have been discussed in the literature, and will be dealt with in the following sections. But there is another approach -- called the "cosmic miracle" -- which bypasses entirely the need for mutual acquisition. The cosmic miracle method allows one civilization to detect another without that other necessarily being aware it has been discovered. Essentially, the idea is to try to observe a kind of "cosmic advertisement" that says, loud and clear, "Here we are! Look at us!" The advertisement may be purposeful, or merely the natural byproduct of large-scale astroengineering projects. But it should be obvious.
It is surprisingly difficult to imagine a plausible celestial signpost that is clearly artificial. At first, it seems simple enough. For instance, imagine we design a brilliant glowing "billboard" in the sky. It should be rectangular in shape with sharp edges and distinct vertices, and measure some fraction of a light-year on a side (say, 0.3 light-years). We make its color fiery crimson to attract the attention of visible-visioned creatures. At the exact center of this celestial marquee we place our premiere attraction: The star system to which we wish to call attention. The adjacent star field, as viewed from the most probable direction of contact, is nearly empty, so the star of our show has little competition for the spotlight. Surely such a setup would be "clearly artificial," a sufficiently strange cosmic miracle to warrant the conclusion of sentient extraterrestrial intervention?
Sorry not! The above is an excellent description of the so-called "Red Rectangle" (actually it is shaped more like a very fat hourglass), discovered by astronomers back in 1915. The object, located near the southern border of the constellation Monoceros, lies 1100 light-years from Earth. The central star (HD 44179) is a visual binary, and both components are believed to be late spectral class B.3102 Astronomers have attempted to explain the appearance of the rectangle as a complicated reflection of reddish starlight from a surrounding disk of dust.2076
Many unusual possibilities crop up repeatedly in the literature. One proposal is to place in orbit around the target star a cloud of material that absorbs some uncommon band of radiation in the stellar spectrum. Viewed from afar,’ the star would appear to possess an artificial spectral line of unknown origin. The creation of such a stellar marker, as discussed by Drake and several others, would require dumping perhaps 400 tons of matter into circum stellar orbit.312 This marker material ought to be of a type that is difficult to explain by natural causes -- for example technetium, a short-lived element (half-life 2 million years) which does not occur naturally on Earth or, presumably, other worlds generally.’ It is said by the proponents of this scheme that the presence of unusual markers in the spectrum of a stellar atmosphere would be difficult to explain as anything other than fairly recent technological activity by alien beings. Unfortunately, a great many natural "technetium stars,"3103 "platinum stars,"3104 and so forth are already known to astronomers.
Philip Morrison at MIT has suggested that a star could be converted into a giant signaling beacon if an opaque screen of dense particles were placed in orbit around it. The clouds would periodically cut off enough light (in certain preferred directions) so that the sun would appear to be flashing when seen from a distance. According to Morrison:
[The cloud] would have to weigh about 1017 kilograms (the mass of a comet), distributed in micron-size particles over a 50 zone of a sphere surrounding the star, and moving in an orbit like the orbit of a planet. If this could be modulated every six months or so., taken away and put back again, or changed to affect the interstellar intensity, we could make it beam a series of algebraic equations at us. Perhaps in that remote galaxy, some patient signalers have for 50 million years tried to modulate a star.1053
(In 1970 it was reported that the eclipsing binary star CV Serpentis had stopped eclipsing, for reasons unknown.1163)
Still stranger sights have been observed in the sky by astronomers. There are Cepheid stars and RR Lyrae variables, suns which beat like great cosmic hearts, expanding and contracting rhythmically over fixed intervals of time. (The surface area of such objects actually grows and shrinks by as much as 40% during each cycle.1810) Cepheids typically are 3000 times more luminous than Sol, with periods between 1-100 days. RR Lyrae variables are about 100 times brighter than Sol, with cycles from 7-16 hours. Each star in this class of objects has its own unique period of pulsation from which it never varies. For instance Polaris, Earth’s "north star," is a Cepheid variable beating with a period of exactly 3 days, 23 hours, 13 minutes, and 31 seconds.1556 (Brightness oscillates over 0.1 magnitude, too little to notice with the naked eye.) Cepheids have also been known to change color, say, from yellow-green to orange and back again, during a cycle. What a fine display of "unnatural" behavior for xenologists to attribute to the doings of sentient ETs!
There are "flash stars," cool main sequence suns which blaze up several orders of magnitude in brightness in just seconds, at irregular intervals. (They return to their normal state minutes or hours later.) Another possible candidate for "cosmic miracle" is the class of suns known as "spectrum variable stars." These suns display a periodic change in the intensity of certain spectral lines, while all the other lines remain constant. To take an example, a2 Canum Venaticorum has a spectral period of 5.5 days. During this interval the spectroscopic lines of the chemical ions EuII and CrII vary cyclically with opposite phases, while the SiII and MgII spectral lines remain unchanged.1945
Then there are the so-called "interstellar masers," regions in space where natural radio lasers emit perfectly monochromatic radiation.3134 In one case, a water vapor maser (IC 1795) was observed to "turn on" over an 8-day period, and then "turn off" again after 1 month.3106 The recently discovered objects known as Cygnus X-l and HZ Herculis are supposedly natural x-ray lasers,3140 and the Crab Nebula provides an example of a natural gamma-ray laser.3163 Recent satellite surveys of x-ray point sources in the Milky Way have uncovered transient sources which flick on, then off again in the space of a few months. It is estimated that several hundred such objects may turn on and off in our galaxy each year, but astronomers still don’t understand why.3140 And there is at least one report of a gamma-ray burster with a mysterious "gap of silence" timed to occur exactly at the peak of its burst.3162
Perhaps a beacon consisting of a rare lasing material (say, ionized deuterium) might be considered sufficiently strange to be judged artificial, but this is highly problematical. And causing a celestial maser or laser to blink doesn’t help us at all -- pulsars flash in one-second cycles, and x-ray and gamma-ray* bursts of incredible intensity are observed over periods of 10 seconds or less.3141 Other sources pulse semiregularly. Over an interval of a day and a half, source Centaurus X-3 emits x-ray flashes that slowly increase in duration from 4.84 to 4.87 seconds, then suddenly drop in intensity in about an hour, then return to normal 12 hours after that.1478
* According to the "catastrophe interpretation," gamma-ray pulses are the remnants of huge nuclear explosions, the last remaining traces of a vast war fought between distant extraterrestrial civilizations.3153
Last updated on 6 December 2008