© 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

24.2  Extraterrestrial Signaling

Let us assume that, for whatever reasons, an extraterrestrial civilization decides to signal rather than travel. What is the best way to do this?

The current majority opinion among xenologists is aptly summarized by Dr. Bernard M. Oliver of the Hewlett-Packard Corporation. According to Dr. Oliver, in order to receive information-laden transmissions we must at the very least be able to detect the presence or absence of a signal. To reliably pick up a pulse packet, the average number of particles in each such pulse must be great enough significantly to exceed the natural background noise in the communication channel used. In other words, signal must rise above noise.

Borrowing Drake’s Principle of Economy, Oliver then suggests that ETs will choose that signaling channel which best conserves transmitter power and which costs the least energy per bit to send. There are five criteria which may determine the particles of choice for frugal alien communicants:

1. The energy per particle should be as low as possible.

2. The velocity of transmission should be as high as possible.

3. The particles should be easy to generate, launch, and detect.

4. The particles should not be deflected by fields in space.

5. Absorption by interstellar matter should be as low as possible.

In his analysis for the Project Cyclops team, Oliver continues:

Except for photons, uncharged particles are difficult to accelerate, direct, and detect. Charged particles are deflected by magnetic fields, are absorbed by matter in space, and, except at very high energies, do not penetrate atmospheres. The total energy of a photon at 1420 MHz {radio} is one ten-billionth the kinetic energy of an electron traveling at half the speed. Photons are as fast as any known particle, are affected very little by the interstellar medium at low frequencies, and are the least energetic. Almost certainly electromagnetic waves of some frequency are the best means of interstellar communication.^57,85

While many xenologists probably remain in basic agreement with this position,²² a few permit themselves the luxury of a nagging doubt. One of these persons is Carl Sagan, who, in an oft-quoted passage from his book The Cosmic Connection, suggests that:

We are like the inhabitants of an isolated valley in New Guinea who communicate with societies in neighboring valleys (quite different societies, I might add) by runner and by drum. When asked how a very advanced society will communicate, they might guess by an extremely rapid runner or by an improbably large drum. They might not guess a technology beyond their ken. And yet, all the while, a vast international cable and radio traffic passes over them, around them, and through them.. . .At this very moment the messages from another civilization may be wafting across space, driven by unimaginably advanced devices, there for us to detect them -- if only we knew how.¹⁵

The answer may lie right under our noses. Until this century it was widely believed that no material object could travel faster than the speed of sound. Yet the crack of a whip, involving the supersonic snap of the tip of the lash, had been known (but not understood) for thousands of years. Sagan, asserting that messages from advanced civilizations may lie in quite familiar circumstances, puts forth a fanciful suggestion:

Consider, for example, seashells. Everyone knows the "sound of the sea" to be heard when putting a seashell to one’s ear. It is really the greatly amplified sound of our own blood rushing, we are told. But is this really true? Has this been studied? Has anyone attempted to decode the message being sounded by the sea shell? I do not intend this example as literally true, but rather as an allegory. Somewhere on Earth there may be the equivalent of the seashell communications channel. The message from the stars may be here already. But where?¹⁵

Philip Morrison once noted that the really logical mode of interstellar communication may be by "Q" waves "that we are going to discover ten years from now."⁷⁰² Others have proposed highly speculative modes of virtually instantaneous contact, including wormhole switchboards,²¹⁸¹ L- or T-fields and Universal Mind,²⁵⁹⁷ and psychic phenomena. Dr. Jack Sarfatti has attempted to invest ESP with scientific validity, using his theory of Superluminal Quantum Communication. (See Gardner,³¹⁴⁵ Sarfatti,^3147,3148 and Sarfatti, Wolfe, and Toben.³¹⁴⁶) The essence of this theory is that it may be possible to transmit the "quality" of energy rather than the energy itself -- which Sarfatti describes as the "nondynamical transfer" of information. Robert Forward articulates a similar notion:

Do we need communication media? Communication is the transfer of information by modulation of some form of mass-energy or space/time. But information has the dimensions of negative entropy. It is not energy by itself. It is carried on energy. It might be possible to transfer information without using any form of mass/energy to transmit it. This is of interest because Special Relativity only limits the velocity of mass/energy, not information. (Some theorists will argue with this.) But still, this leads to a speculation that we might someday have faster-than-light information transfer even though mass/energy cannot go faster than c.²⁰¹⁴

These and many other highly conjectural possibilities today remain only at the "idea" stage of technical development on this world.* Interestingly enough, however, there are at least four alternative signaling channels in which significant progress has been achieved in recent decades. The first two -- high energy particle and neutrino communications -- have, perhaps surprisingly, already reached the "practice" stage of engineering and development here on Earth. The other two techniques we shall discuss -- gravity wave and tachyon communications -- presently remain at the "theory" stage of technological development. They await verification and research before serious engineering efforts may begin.

* It will be recalled from Chapter 17 that technical progress and the realization of new technology normally proceeds in four distinct stages: Idea, Theory, Practice, and Profit.

Last updated on 6 December 2008