All Commentary
Monday, June 1, 1992

The Search for Extraterrestrial Intelligence

Mr. Finneran is a writer from Marshfield, Massachusetts.

One could have wished that this excellent instrument had been preserved for a longer period in this place, and had stayed in use, or else, that another instrument had been constructed in its place. Since, however, men as a rule are more interested in worldly matters than in things celestial, they usually regard with indifference such happenings which will perhaps be more harmful to themselves than they themselves realize.

—Tycho Brahe, the great 16th-century Danish astronomer, on the ruining through government neglect of a giant quadrant he had constructed.[1]

Tycho’s lament is common among scientists who rely on government funding. As Tycho discovered, the state can be a wobbly crutch, since government aid can vary greatly from year to year.

One scientific program currently receiving federal support is SETI—the search for extraterrestrial intelligence. SETI consists mostly of listening for alien communication signals, although, in some cases, signals are sent from Earth in the hope of provoking a response. The importance of SETI has been summed up by Lewis White Beck, who pointed out that, if intelligent aliens are discovered, “there is no limit to what in coming centuries we might learn about other creatures and, more portentously, about ourselves. Compared to such advances in knowledge, the Copernican and Darwinian Revolutions . . . would have been but minor preludes.”[2]


Is There Extraterrestrial Intelligence?

Great thinkers have debated the likelihood of extraterrestrial intelligence for many centuries. The probable existence of intelligent aliens has been supported by Aristotle, Plutarch, Lucretius, Nicholas of Cusa, Giordano Bruno, Pierre Gassendi, John Locke, Johann Heinrich Lambert, and Immanuel Kant. It has been opposed by Albertus Magnus, Augustine, and Thomas Aquinas.[3]

The mathematical probability that extraterrestrial life exists and will attempt to communicate with Earth was expressed by Frank Drake: The probability = (the probability that a given star system has planets) x (the number of habitable planets among those planets) x (the probability that life evolved on those planets) x (the probability that intelligence developed among planets with life) x (the probability that an intelligent species will attempt interstellar communication within five billion years after the formation of its planet). The problem with the Drake equation, of course, is that many of the variables are unknown, so that, depending on the numbers you plug in, the results can vary widely.

Those who doubt the existence of extraterrestrial intelligence point to the apparent lack of von Neumann machines on Earth. According to a theory put forward by the mathematician John yon Neumann, a yon Neumann machine could enter a galaxy and, using the raw materials it finds, build replicas of itself. The universe could rapidly be explored by numerous von Neumann machines expanding in all directions. Therefore, goes the argument, since a technologically advanced alien society has not yet sent von Neumann machines to Earth, such an alien society does not exist.[4]

However, proponents have a number of counter-arguments. Carl Sagan and William I. Newman contend that if von Neumann machines had limited reproduction, then their absence on Earth would be understandable. If, on the other hand, von Neumann machines’ replication could not be limited, then it would be dangerous to build them in the first place, lest, like a cancer, their numbers should grow uncontrollably.[5]

The debate about the existence of extraterrestrial intelligence, then, is inconclusive. But, given the doubts that alien intelligence exists, and the rival demands for funds, SETI is low on the list of congressional priorities. There have been a number of SETI searches, but scientists often have had to share telescopes and reuse data collected for other purposes.


Unofficial Searches

However, SETI is not a government monopoly. Faced with limited funding, SETI enthusiasts are becoming more self-reliant. Once more, Tycho Brahe anticipated the problem, and he also anticipated the response:

Since a very limited number of people occupy themselves with these celestial sciences and enterprises, and since it is very seldom that among the statesman who wish to govern a state that there are any so strongly attracted by these sciences that they consider it their duty to favor and support them, but are much more often repulsed by them and consider them futile, owing to their ignorance; so the person who cultivates divine astronomy ought not to let himself be influenced by such ignorant judgments, but rather look down upon them from his elevated position, considering the cultivation of his studies the most precious of all things, and remaining indifferent to the coarseness of others.[6]

A number of “cultivators of divine astronomy” have heeded Tycho’s advice and taken astronomy into their own hands. There have been a number of unofficial searches. A group of enthusiastic amateurs in California have turned their home computers into makeshift SETI signal analyzers. This amateur SETI project is called, appropriately, AMSETI.[7]

Discoveries, however, often occur not because of conscious design, but as the happy fruit of circumstance. Christopher Columbus’s search for a shorter route to India resulted in the discovery of the New World, and several theorists have speculated that a similarly unintended event may alert extraterrestrials to our existence.

In fact, radio, television, and other communications signals broadcast over the years continue their journeys into space, so they may be more likely to be discovered than directed signals.[8] Indeed, we might witness an alien response via television or radio, evident to any viewer sitting in his living room or to any listener in his car—and make a mockery of our scientists’ sophisticated listening apparatuses. Thus could a wayward broadcasting signal act as an inadvertent Columbus, making known to some new world the existence of our old. 

1.   Bernard Lovell, “Tycho Brahe” in History Today, October 1963, p. 680.

2.   Lewis White Beck, “Extraterrestrial Intelligent Life” in Edward Regis Jr., editor, Extraterrestrials: Science and Alien Intelligence (New York: Cambridge University Press, 1987), p. 15.

3.   Ibid, pp. 3-18.

4.   This is the argument in Frank J. Tipler, “Extraterrestrial Intelligent Beings Do Not Exist,” pp. 133-50 in Regis.

5.   Carl Sagan and William I. Newman, “The Solipsist Approach to Extraterrestrial Intelligence,” pp. 151-61 in Regis.

6.   Lovell, p. 684.

7.   Jill Tarter, “Searching for Extraterrestrials” in Regis, p. 181.

8.   Ibid.