Science in Christian Perspective




Religion and the Search for Extraterrestrial Intelligence

Joseph L. Spradley*

Department of Physics
Wheaton College
Wheaton, IL 60187-5593

From: PSCF 50 (September 1998): 194-203. 

Some scientific visionaries have suggested that the best hope for achieving peace and prosperity on Earth, and perhaps immortality itself, is through help obtained by communicating with extraterrestrial civilizations. The idea of a plurality of worlds has a long history, but the scientific search for extraterrestrial intelligence (SETI) began only about forty years ago. Although large amounts of money and scientific effort have been expended in pursuit of these ideas, analysis shows how extremely improbable they are. Recent SETI literature reveals that this effort is sustained by quasi-religious motivations, but both the possibility and improbability of alien contact have theological implications relating to Christology and human significance.

The August 1996 announcement by NASA of meteoritic evidence that life might have existed on Mars some 3.6 billion years ago has given new hope to those who believe that extraterrestrial intelligence exists elsewhere in the universe.1 This announcement was hailed as "the biggest thing that has ever happened," even though it was qualified by several disclaimers.2 If evidence for microbial life on Mars is confirmed, it raises new questions about the ubiquity of life. It also does not begin to resolve many other problems that the idea of extraterrestrial intelligence and the quasi-religious faith which sustains it present.

For many centuries, extraterrestrial spiritual beings have been a part of the faith of Western religions. They appear in the form of immortal angels, servants of God who visit Earth with special messages of guidance and salvation. With the rise of modern science and the development of radio astronomy, a new faith has emerged for some scientific visionaries, who believe in the possibility of extraterrestrial material life. It is their hope that such life might have evolved on other planets among the billions of stars in our galaxy, producing higher forms of intelligence which could communicate to us the knowledge and wisdom of their experience, perhaps even imparting the secrets of peace and immortality. Yet a careful analysis of this idea reveals the futility of a search for extraterrestrial intelligence (SETI) and the religious motivations behind it. Such an analysis, however, can lead to a new appreciation for the miracle of human life as we know it.

The idea of extraterrestrial life and intelligence is not necessarily inconsistent with a Christian perspective. The Roman Catholic theologian and former president of the University of Notre Dame, Father Theodore M. Hesburgh, is enthusiastic about this idea:

It is precisely because I believe theologically that there is a being called God, and that He is infinite in intelligence, freedom and power, that I cannot take it upon myself to limit what He might have done. Once He created the Big Bang...He could have envisioned it going in billions of directions as it evolved, including billions of life-forms and billions of kinds of intelligent beings...As a theologian, I would say that this proposed search for extraterrestrial intelligence (SETI) is also a search of knowing and understanding God through His worksˇespecially those works that most reflect Him. Finding others than ourselves would mean knowing Him better.3

Evangelical astronomer Owen Gingerich of the Harvard-Smithsonian Center for Astrophysics agrees: "In Genesis there's a sacred story being told that focuses on us. But there is nothing that precludes intelligent life elsewhere in the universe. It would be extremely arrogant to limit God's creativity to human beings as the only contemplative creatures in the universe."4 Yet moving from the possibility of extraterrestrial intelligence to an expensive search for radio signals from advanced extraterrestrial civilizations should be based on a rational assessment of the probability that such beings exist. The fact that this probability turns out to be extremely low has significant religious implications.

Historical Background

The medieval synthesis of Christian doctrine and Aristotelian cosmology by Thomas Aquinas established the centrality of the Earth and the special place of humans within a finite universe, discouraging the idea of other worlds. Although Thomistic theology came to dominate medieval Christianity, a tradition soon emerged to challenge Aristotelian ideas that might limit the omnipotence of God. In 1277 the Bishop of Paris, Etienne Tempier, issued a condemnation of some 219 propositions that he considered too restrictive of divine omnipotence, including that God could not make several worlds.

Several theologians who questioned Aristotelian ideas raised the possibility of a plurality of worlds. Basing his opinion on Augustine's idea that God could have made a perfect man, William of Ockham, the fourteenth-century Oxford Franciscan, declared it probable that God could create a better world than ours, and certain that he could create an infinite number of worlds identical to ours. Fifteenth-century Cardinal Nicholas of Cusa not only recognized that the universe can have no center, but also suggested the possibility of other earth-like planets, including more illustrious extraterrestrials close to the sun and lunatics on the moon. Although it became heretical to deny that God could create other worlds, it was dangerous to claim that he had.5

The Sun-centered system of Nicholas Copernicus not only displaced human life from the center of the universe, but it also implied that the stars are suns like our own. This belief led the Dominican monk, Giordano Bruno, to suggest that there might be an infinite number of suns with inhabited planets and that even stars might be inhabited.6 He was attracted by the Greek atomic theories of Democritus and Epicurus, who had suggested the idea of an infinity of worlds, as atoms form different combinations in infinite space. Bruno believed that God's omnipotence and infinitude could only be expressed by creating an infinite number of worlds in reality, not just as a hypothetical possibility. Unfortunately, he was arrested in 1592 and his works were condemned by the Inquisition, leading to his death in 1600 when he was burned at the stake.

Protestants also reacted to the plurality of worlds, especially with the increasing Reformation emphasis on the authority of Scripture. In 1578 L. Danaeus stated that the idea of life on other planets should not be accepted since it was not taught in Scripture.7 This argument is complicated, however, by the fact that planets also are not mentioned in Scripture. Philip Melanchthon argued against the plurality of worlds because their inhabitants might be left without a knowledge of Christ or that his death and resurrection might have been required more than once. Furthermore, Genesis states that God rested on the seventh day and thus did not start work on other worlds.8

In the seventeenth century, the scientific revolution brought more speculation about other worlds. Kepler suggested that the moon might be inhabited by beings with large bodies to withstand the long, hot lunar days. He also believed that the four moons of Jupiter, discovered by Galileo, were made by God for the benefit of Jovian inhabitants, proving that other planets are inhabited. This led Kepler to wonder if such beings would infringe on God-given human dominion over his creation.9 Galileo was more cautious in his Dialogues Concerning the Two Chief World Systems (1632) when discussing the possiblity of habitation on the moon and planets. His friend Ciampoli warned him against such speculations, since it would invite awkward questions about how the descendants of Adam and Eve reached the moon.10

By the end of the seventeenth century, the idea of other worlds became more widely accepted, but with decreasing emphasis on the doctrine of redemption.

English clergyman (later Bishop) John Wilkins took the silence of Scripture not as a ban, but as an invitation to consider the possibility of other worlds. In his book, Discovery of a World in the Moone (1638), Wilkins strongly argued for lunar inhabitants, insisting that this idea did not conflict with Scripture. He suggested that intelligent beings on other worlds need not be like humansˇfallen from grace; but even if they had, Christ could have died for them also.11 By the end of the seventeenth century, the idea of other worlds became more widely accepted, but with decreasing emphasis on the doctrine of redemption. Fontenelle's influential book, The Plurality of Worlds (French, 1686; English, 1688), shifted attention from the Earth and its puny drama to the vastness of the universe and science as a new kind of theology that believed in many worlds.12

Newton's law of universal gravitation implied the universality of natural laws. Other stars, therefore, might have their own planetary systems. His friend, Richard Bentley, used Newtonianism to argue that God would not have made so many stars just for human purposes, and thus they must be for the benefit of their own planetary inhabitants. English theologian Robert Jenkin tried to relate other worlds to a Christian view:

I observe, that though it should be granted, that some Planets be habitable, it doth not therefore follow, that they must be actually inhabited, or that they ever have been...And since the fall and mortality of mankind, they may be either for mansions of the righteous, or places of punishment for the wicked, after the resurrection...And in the meantime, being placed at their respective distances, they do by their several motions contribute to keep the world at a poise, and the several parts of it at an equilibrium in their gravitation upon each other, by Mr. Newton's principles.13

For eighteenth-century thinkers, creation prevailed over redemption and the plurality of worlds became commonplace. Alexander Pope's Essay on Man (1734) expressed the spirit of the day with its faith in other inhabited worlds:

He who thro' vast immensity can pierce,
 See worlds on worlds compose one universe,
Observe how system into system runs,
What other planets circle other suns,
What vary'd being peoples ev'ry star,
May tell why Heav'n has made us as we are.14

English naturalist John Ray believed that life on other planets could be used to contemplate God's creative work just as the multitude of species reveal the wisdom and power of God.15 By the end of the century, Immanuel Kant wrote extensively on extraterrestrial beings without fear of ridicule.

By the middle of the nineteenth century, a new attitude of caution began to discourage extraterrestrial speculation.

By the middle of the nineteenth century, a new attitude of caution began to discourage extraterrestrial speculation. In 1853 philosopher and historian of science William Whewell, Master of Trinity College, Cambridge, and formerly a supporter of other inhabited worlds, published a tract entitled Of the Plurality of Worlds: An Essay which attacked the idea of alien beings. This tract produced intense debate on the issue of extraterrestrial life on philosophical, theological, and scientific grounds. Alfred Russell Wallace, the co-founder of the theory of evolution, was especially impressed with the contingent nature of evolution and the sheer improbability of the emergence of human intelligence. Late in life he used this argument against astronomers searching for signs of intelligent life on other planets in a book called Man's Place in the Universe (1903). Despite this growing skepticism, a few astronomers persevered in their search for alien intelligence.

The Origins of SETI

By the beginning of the twentieth century, U.S. astronomer Percival Lowell claimed to have observed 437 canals crisscrossing the surface of Mars, leading to speculation that they formed an enormous irrigation network to channel water from melting polar caps to vegetation near the equator.16 Some feared that such efforts on a dying planet might lead to an invasion of the Earth for its resources. This fear was exploited in 1938 by Orson Welles' Halloween radio broadcast which dramatized H.G. Wells' novel, War of the Worlds (1898), and convinced many that Martians had invaded. The development of new technologies during and after World War II, including radar, rockets, satellites, and space probes, led to a postwar rise in fascination with aliens by nonprofessionals and scientists alike.

The development of new technologies during and after World War II, including radar, rockets, satellites, and space probes, led to a postwar risein fascination with aliens by nonprofessionals and scientists alike.

During the 1960s, three American Mariner spacecraft passed near Mars and sent back pictures revealing that the canals were an optical illusion. In 1976 two Viking spacecraft which landed on Mars found no evidence of life of any kind. Most scientists agree that life must be based on the chemistry of carbon and water since only carbon has the kind of bonding that can produce the complex molecules necessary for life, and water is its best solvent. The recent discovery that a Martian meteorite contains evidence for life, including carbonate globules that crystallize in the presence of water, minerals in the globules similar to bacterial residue, hydrocarbon compounds, and tubular microfossils similar to but much smaller than the oldest bacteria fossils found on Earth, suggests that microbial life might once have existed on Mars 3.6 billion years ago, continuing the Martian mystique.17

Of the nine planets in the solar system, only Earth is known to harbor intelligent life. Recent theories and observations of planet formation suggest that planets might be fairly common for sun-like stars. Among a few hundred billion stars in our galaxy, many could have planets and thus the possibility of life elsewhere seems worthy of consideration. About 100 billion galaxies in the universe vastly increases this possibility, but light from the nearest spiral galaxy (with sun-like stars) takes two million years to reach us. Thus, any realistic possibility of communicating with extraterrestrial civilizations would appear to be limited to our own Milky Way galaxy.

In 1961, at the National Radio Astronomy Observatory in Green Bank, West Virginia, Frank Drake developed a simple equation to estimate the number N of intelligent civilizations in our galaxy.18 The Drake equation, which came from the agenda for the first SETI meeting (ten participants at Green Bank), is a product of seven factors:

N = R*  x  fp x ne x  fl x fi x fc x L

where R* is the rate of star formation per year, fp is the fraction of stars that have planets, ne is the average number of planets per star with environments suitable for life to develop, fl is the fraction of planets with life, fi is the fraction of planets where intelligent life develops, fc is the fraction of planets with advanced civilizations, and L is the lifetime of advanced civilizations. At the Green Bank meeting, the product of the first six factors was optimistically assumed to be one, reducing the equation to N=L.19 Thus the lifetime of an advanced civilization became the critical factor, but also the most uncertain.

In 1966, Russian astronomer Iosef Shklovskii and American astronomer Carl Sagan assumed that the factors in the Drake equation are R* =10 stars/year (100 billion stars formed over the last 10 billion years), fp=ne=fl=1, fi=fc=0.1 and L=10 million years to estimate that the maximum possible number N is about a million advanced civilizations in our galaxy (0.001% of all stars).20 More recent discoveries have shown that the factors in this equation are much smaller than these values. Yet even with this optimistic estimate, which is often quoted in the SETI literature, the average distance between stars with such civilizations would be about five hundred light years.

Two-way communication with extraterrestrial civilizations appears to be all but impossible, since anyone sending a message at the speed of light would have to wait at least a thousand years for a response. However, with the development of radio astronomy since World War II, some astronomers have had high hopes that a properly tuned radio telescope might be able to intercept intelligent radio signals from extraterrestrial civilizations that would have reached a high level of technology several thousands of years ago. A search for extraterrestrial intelligence using radio telescopes has been compared with looking for a needle in a cosmic haystack, since radio signals from even a million advanced civilizations among the hundreds of billions of stars in our galaxy would require observations of several hundred thousand stars to have a chance of finding just one star emitting such signals toward us. Furthermore, for each observed star, a radio telescope would have to be tuned sequentially to billions of radio-frequency channels.

The modern radio-frequency search for intelligent signals was initiated by SETI pioneers, Giuseppe Cocconi and Philip Morrison in 1959.21 They called attention to the microwave window from about one GHz (a billion vibrations per second) to ten GHz, where natural radiation noise reaches a minimum value between noise from the galaxy and absorption in the Earth's atmosphere. They also suggested that a natural channel for communicating across space might be the 1.420 GHz frequency (21-cm. wavelength) at which hydrogen atoms vibrate in interstellar space, since an advanced civilization would presumably realize that astronomers would often tune their radio telescopes to this frequency to study the distribution of hydrogen in the galaxy. The hydroxyl (OH) molecule, which combines with hydrogen to form water, also vibrates near this frequency, so this region of the microwave spectrum is called the "cosmic waterhole" by SETI enthusiasts.22 Extraterrestrial transmitters would have to be beamed toward Earth with higher power than the most powerful radio transmitters on Earth, since these can send signals discernible from cosmic noise only about 500 light years into space.

In 1960 Frank Drake attempted the first modern SETI with an 85-foot dish radio telescope at Green Bank...

In 1960 Frank Drake attempted the first modern SETI with an 85-foot dish radio telescope at Green Bank in a project he called Ozma, named after the queen of the imaginary land of Oz.23 He focused on two nearby sun-like stars for about 400 hours and soon picked up radio signals from the direction of the second one, only to find later that they were interference from a terrestrial source. In recent years, multi-channel receivers have been developed that can match Drake's effort in less than a second.

In 1967 a graduate student at Cambridge University named Jocelyn Bell picked up rapid radio pulses from several sources in the galaxy with a new radio telescope consisting of hundreds of wire antennas spread over five acres. Eventually these "pulsars" were shown to be natural sources that could be explained as radio emissions from rapidly rotating neutron stars. After eight years of "listening" with a large radio telescope at Ohio State University, an unusual signal was detected in 1977, but this so-called "Wow!" signal never appeared again. Since 1960, astronomers from half a dozen countries have conducted about 60 SETI searches of several hundred stars with no confirmed results.24

The Futility of SETI

The inability to detect artificial radio signals from space led some scientists, including Shklovskii, to question the existence of extraterrestrial intelligence. In 1975 at Cambridge University, Michael Hart argued that advanced civilizations lasting a few million years would explore and colonize the galaxy much like we have explored and colonized the Earth in the last five hundred years.25 With space travel at about 10% of the speed of light, less than a million years would be required to colonize the entire galaxy. Thus many extraterrestrials, perhaps with advanced medicine giving them life spans of several millennia or longer, should have reached us by now. The fact that no such beings have arrived led him to conclude that there are no such advanced civilizations in our galaxy.

In 1981 U.S. physicist Frank Tipler finally succeeded in publishing an article entitled "Extraterrestrial Intelligent Beings Do Not Exist," after Sagan had refused its publication in two journals.26 Tipler reasoned that if the galaxy has contained advanced civilizations for millions of years, at least one of them would have sent unmanned probes into our solar system by now. These views echoed a statement by Nobel physicist Enrico Fermi in 1950 known as the Fermi Paradox: "Where are they?" This argument was convincing enough to lead Senator William Proxmire to propose an amendment in 1981 that killed NASA's proposed SETI Cyclops Project. This ten-billion-dollar project would have constructed 1,500 closely spaced radio telescopes, each with a 300-foot dish. Frank Drake claimed it would have been "probably the most rewarding use of tax dollars in history."27 Despite this setback, more than 100 million dollars of taxpayer money was spent on SETI programs in the 1980s. A similar sum was approved for the NASA-SETI Microwave Observing Project (MOP), which features a megachannel analyzer that can scan 28 million frequencies and automatically identify intelligent signals.28 MOP was canceled in 1995, but continues as the privately funded Project Phoenix.

Since Shklovskii and Sagan's original optimistic estimate of one million possible extraterrestrial civilizations, many other factors have been identified for inclusion in the Drake equation that lead to a very low probability for any life-supporting planet. For example, Michael Hart has used computer simulations to show that only G (spectral class) stars have the right mass and luminosity to support a continuously habitable zone for planets.29 This reduces the rate of suitable star formation (R*) from 10 stars per year to about 0.001 star per year.

Since Shklovskii and Sagan's original optimistic estimate of one million possible extraterrestrial civilizations, many other factors have been identified...that lead to a very low probability for any life-supporting planet.

The fraction of stars with suitable planets (fp) is also much less than early estimates. Only about 10% of G stars are single (not part of a multiple-star system) and therefore could have stable planetary orbits. In addition only 10% of these rotate slowly enough to have planets. Recent evidence suggests that the formation of sun-like stars with solar systems is strongly affected by the relatively rare phenomenon of a nearby supernova explosion, which occurs only about once every century in our galaxy. In spite of these improbable factors, Rood and Trefil offer a generous probability of 0.1 for planet formation about a suitable star.30

Another study by Hart shows that the number of habitable planets per star (ne) is greatly limited by the fact that only planets differing about 5% from the equivalent earth-sun distance can avoid either a runaway greenhouse effect or runaway glaciation.31 A similar narrow range for the size, tilt, and rotation rate of a habitable planet is required to retain the right atmosphere and climate. Recent studies show that the unusually large moon of the Earth is critical in maintaining a stable tilt of the Earth's axis and the associated climatic stability required for life.32 The best theories of the moon's origin suggest that it was captured in a grazing collision by a Mars-size asteroid, an event that may be extremely rare for an earth-size planet.

 A habitable planet may also require a Jupiter-size planet beyond its orbit to sweep up asteroids and comets that would otherwise hit it. The Earth is struck by asteroids large enough to cause mass extinctions about every 100 million years. Without Jupiter this rate would be one every 100,000 yearsˇ too often to permit the development of higher forms of life.33 Recent observations of 120 stars have revealed seven with tiny wobbling motions that could be caused by Jupiter-size planets, but all have been much closer than Jupiter to their host star, suggesting that our solar system is not a typical planetary arrangement.34 Such giant planets moving so closely would have completely disrupted any earth-like planets, perhaps even capturing them by their huge gravitational effects.

 The fraction of habitable planets on which life might develop (fl) is even more problematic, but certainly less than early suggestions of a probability of 1. If the discovery of evidence for microbial life billions of years ago on Mars is confirmed, this fraction might be enhanced, but it also would show that such life does not develop inevitably into higher forms. The development of life depends on many chemical and biological factors, including the formation of simple organic molecules and amino acids, the joining of these molecules into long chains (polymerization), the separation of these polymers into isolated systems, the development of reproductive capacity by these systems, and the formation of these simple reproducing systems into cells and complex organisms. These factors in turn depend on such physical conditions as the formation of ozone to protect from ultraviolet radiation, the right magnetic field strength to prevent excessive cosmic radiation and ozone depletion, and sufficient lightning to fix nitrogen in the atmosphere. Even without considering the special molecular ordering required for viable life, the probability of these events is very low. Rood and Trefil offer a generous probability of 0.01 for these events.

Hart believes that the probability for the formation of a self-replicating gene dominates any of the other probabilities. Using very generous assumptions about the formation of amino acids, nucleotides, polymerization, uniform molecular helicities (right or left handed), and chemical effects that favor the formation of DNA strands, Hart calculates the probability of spontaneous formation of a relatively short strand of DNA (600 nucleotide residues with 100 in the proper order) to be less than 10-30 in a period of ten billion years. The simplest known organism, containing about 100 different genes, has a chance of less than (10-30)100=10-3000 of spontaneous formation!35 These vanishing probabilities are contested by writers such as Richard Dawkins and Stuart Kauffman, who propose multiple-step selection processes and self-organizing systems to suggest that the origin of life is not very unusual.36 If such ideas are confirmed, it is hard to understand why life did not begin several times on Earth, producing diverse genetic ancestries. Even the simplest form of life on Mars might support the idea that life is not so unusual, unless it originated only once on either Mars or Earth and was then transplanted between them. Hugh Ross gives several reasons to expect microbial life on Mars ejected from Earth.37

Most biologists insist that the course followed by evolution is unrepeatable, and that no species can ever evolve twice.

For development of intelligence (fi) and of advanced technological civilizations (fc), Rood and Trefil offer very optimistic estimates of 0.5 each, higher even than the Sagan and Shklovskii values of 0.1 for each of these fractions. Most biologists insist that the course followed by evolution is unrepeatable, and that no species can ever evolve twice. Billions of species on Earth over billions of years have resulted in only one with enough intelligence to develop technology, compared to about 40 species that have developed various kinds of eyes. Thus, most evolutionary biologists such as George Gaylord Simpson tend to be much more pessimistic than SETI enthusiasts about the development on other planets of any kind of intelligence with which we could communicate, concluding that its probability is vanishingly small.38 This neo-Darwinian consensus would be challenged if an independent origin for life on Mars is confirmed, and would be completely shattered if signals were received from alien civilizations.

Depending on how many parameters are considered in each of the first six factors of the Drake equation, combined probability estimates range from a "conservative" value of about 10-7 by Rood and Trefil to a very "pessimistic" value of only 10-42 by Hugh Ross.39 Ross considers only astronomical factors that are much less likely to benefit from correlating factors such as the multiple-step processes or self-organizing systems in biology. Thus, even if the Mars data show that life is not improbable in the right environment, and if the lifetime of an advanced civilization (L) is as long as a million years, the probable number (N) of planets in a galaxy with an advanced civilization is still less than one. Taking into account all the factors considered by Ross leads to a vanishing probability that life could exist anywhere in the observable universe of some 1022 stars, suggesting that the existence of life as we know it is nothing short of amazing.

Religious Implications of SETI

Both the possibility and the improbability of extraterrestrial intelligence have interesting religious implications. In view of the many new parameters entering into the Drake equation that reduce the probability of finding extraterrestrial intelligence to a very small value, it is surprising that SETI efforts continue to attract so much interest and funding. Frank Drake's recent autobiographical history of the SETI movement reveals some interesting religious motivations. In fact, his desire to communicate with extraterrestrials from early childhood appears to be a substitute for his traditional religious (Baptist) background:

 I have been waiting for this moment nearly all my life. Indeed, if there is anything unusual about my otherwise normal childhood, it is that I started tracing my ties to alien civilizations of intelligent life in the universe at age eight. I did this in spite of my family's fundamentalist religious beliefs and despite their scorn for fantastic ideas.40

SETI enthusiasts have a strong faith in a higher intelligence which is seeking to communicate with us and which can change our lives and solve our problems. Drake begins his book with these confident affirmations:

Now, after all our efforts over the past three decades, I am standing with my colleagues at last on the brink of discovery...the imminent detection of signals from an extraterrestrial civilization. This discovery, which I fully expect to witness before the year 2000, will profoundly change the world. The point of this book, as of my life's work, is that interstellar contact will enrich our lives immeasurably.41

The SETI hope is that contact with alien civilizations, even if limited to one-way radio reception, will provide a higher level of knowledge that might lead to world peace and human salvation. Drake expresses this hope with the eloquence of a true believer:

I fully expect an alien civilization to bequeath to us vast libraries of useful information, to do with as we wish. This "Encyclopedia Galactica" will create the potential for improvements in our lives that we cannot predict. During the Renaissance, rediscovered ancient texts and new knowledge flooded medieval Europe with the light of thought, wonder, creativity, experimentation, and exploration of the natural world. Another, even more stirring Renaissance will be fueled by the wealth of alien scientific, technical and sociological information that awaits us.42

The SETI hope extends to the possibility of immortality itself; but it falls short of eternal life since it can't survive the end of the universe, whether by a bang or a whimper:

I suspect that immortality may be quite common among extraterrestrials. By immortality I mean the indefinite preservation, in a living being, of a growing and continuous set of memories of individual experience...Sometimes, when I look at the stars║ I wonder if, among the most common interstellar missives coming from them, is the grand instruction book that tells creatures how to live forever.43

Although these religious motivations in the SETI movement may appear naive, other more meaningful religious implications follow from the possibility of extraterrestrial life. Nancey Murphy, theologian and philosopher of science at Fuller Theological Seminary, argues that our significance lies not in being the only intelligent creatures, but in our capacity for relationship with God. Thus she believes "that God's design of the universe should allow for as many relationships as possible," so it is "theologically conceivable that God's creative intentions should include the evolution of other life forms, wherever possible, with comparable intellectual and emotional capacities." She concedes that this possibility raises questions about the special place of humans in the biblical account and the uniqueness of Jesus in the Incarnation.44

The SETI hope is that contact with alien civilizations, even if limited to one-way radio reception, will provide a higher level of knowledge that might lead to world peace and human salvation.

One answer to the problem of the uniqueness of Jesus and the Incarnation was suggested in 1952 by Oxford cosmologist E.A. Milne:

God's most notable intervention in the actual historical process, according to the Christian outlook, was the Incarnation. Was this a unique event, or has it been re-enacted on each of a countless number of planets? The Christian would recoil in horror from such a conclusion. We cannot imagine the Son of God suffering vicariously on each of a myriad of planets.45

Appealing to the new science of radio astronomy, Milne suggested a possible solution through interstellar radio evangelism by beaming the Christian message into space:

In that case there would be no difficulty in the uniqueness of the historical event of the Incarnation. For knowledge of it would be capable of being transmitted by signals to other planets and the re-enactment of the tragedy of the crucifixion in other planets would be unnecessary.45

This resolution was rejected by Oxford philosopher and Anglican priest E.L. Mascall in his 1956 Bampton Lectures. He argued that Milne's theology is deficient concerning the Passion of Christ in supposing that "the necessary and sufficient condition for it to be effective for the salvation of God's creatures is that they should know about it." Mascall felt that this was in sharp contrast with the classical tradition of Christian thought:

For the latter, the essence of redemption lies in the fact that the Son of God has hypostatically united to himself the nature of the species that he has come to redeem...It would be difficult to hold that the assumption by the Son of the nature of one rational corporeal species involved the restoration of other rational corporeal species (if any such exist)...Christ, the Son of God made man, is indeed, by the fact that he has been made man, the Saviour of the world, if "world" is taken to mean the world of man and man's relationships; but does the fact that he has been made man make him the Saviour of the world of non-human corporeal rational beings as well? This seems to me to be doubtful... 46

Mascall also rejected Milne's view of "the tragedy of the crucifixion" as incomplete in not recognizing that the "horror of the crucifixion of God incarnate has been transformed by his resurrection into the supreme glory of the redemption of the human race...If the horror is not unrelieved but is changed into victory and glory, why cannot the change happen again and elsewhere?" This led Mascall to his preferred alternative that the Incarnation is repeated on other planets:

The suggestion which I wish to make, with all the tentativeness that is proper to a matter about which we are in almost complete ignorance, is that there are no conclusive theological reasons for rejecting the notion that, if there are, in some other part or parts of the universe than our own, rational corporeal beings who have sinned and are in need of redemption, for those beings and for their salvation the Son of God has united (or one day will unite) to his divine Person their nature, as he has united to it ours...[If] the Incarnation takes place not by the conversion of the Godhead into flesh but by the taking up of manhood into God, there seems to be no fundamental reason why, in addition to human nature being hypostatically united to the Person of the divine Word, other finite rational natures should not be united to that Person too.47

This solution seems preferable to Milne's on both Christological and scientific grounds, since it recognizes the true nature of the Incarnation and would apply to alien civilizations too far removed in time and space from Earth to ever hear about the crucifixion of Jesus. Paul Tillich seems to agree with this view, but from a cosmic perspective:

Man cannot claim to occupy the only possible place for Incarnation...The interdependence of everything with everything else in the totality of being includes a participation of nature in history and demands a participation of the universe in salvation. Therefore, if there are non-human "worlds" in which existential estrangement is not only real...but in which there is also a type of awareness of this estrangement, such worlds cannot be without the operation of saving power within them.48

Another theological problem arising from the possibility of a message from an alien civilization is that it would very likely be far in advance of ours, challenging Christian ideas about human dominion over creation. Since our solar system is only about five billion years old compared to other stars known to be as much as ten billion years old, any other alien community that communicates with us is likely to be at least a few million years more advanced than our rather recent technological society. Since even a modest advantage in technology can easily appear as magic, such super-advanced aliens who have survived this long would be a challenge to our traditional religious values. Thus they might appear to be gods and raise further questions about human significance in the universe. In Sagan's 1985 novel Contact, advanced alien signals lead to secrets about the universe that reveal an intelligent design. Fred Hoyle's 1983 nonfiction book, Intelligent Universe, offers a similar view of godlike aliens who design the conditions needed for carbon-based life and spread it through the universe.49

Religious implications follow not only from the possibility of extraterrestrial life, but also from the failure of SETI efforts to detect alien signals and from the increasing evidence that intelligent life may be unique to the Earth. For five hundred years, Western culture has been dominated by the Copernican idea that humans are not a central aspect of the universe, but only an accidental result of impersonal forces acting on an average planet circling a typical star among billions in the universe. If evidence that confirms increasingly smaller probabilities for the conditions for life to occur elsewhere continues to accumulate, then the existence of human life on Earth might again be seen as unique and special, reinforcing the biblical revelation of human significance.

The apparent uniqueness of human life has begun to lead some scientists to recognize that our existence must influence the way we understand the universe...

The apparent uniqueness of human life has begun to lead some scientists to recognize that our existence must influence the way we understand the universe, rather than the usual argument that the existence of humanity is accidental and insignificant. In 1974 British physicist Brandon Carter coined the term "anthropic principle" to describe this kind of reasoning. In its strong form, the anthropic principle asserts "that the Universe...must be such as to admit the creation of observers within it at some stage." The weak form states "that our location in the universe is necessarily privileged to the extent of being compatible with our existence as observers."50

The evidence that life requires such fine tuning to beat impossible odds has been compelling enough to lead some to suggest the existence of numerous universes, and that ours just happened by chance to have the right conditions for life. Others have suggested that an oscillating sequence of universes has finally produced one that supports life, in the same way that enough throws of the dice will eventually give the desired result. Although a multiple-universe hypothesis might be one way to resolve the vanishing probability problem, it is a solution with no observable basis and seems to violate the principle that the simplest among equivalent explanations is the best.

If our existence determines the design of our universe, it would seem far simpler and more rational to accept the traditional theistic principle that a Creator has designed our finely tuned universe specifically to contain intelligent life that could understand and appreciate his creation. George Greenstein expresses it this way:

As we survey all the evidence, the thought insistently arises that some supernatural agencyˇor rather, Agencyˇmust be involved. Is it possible that suddenly, without intending to, we have stumbled upon scientific proof of the existence of a Supreme Being? Was it God who stepped in and so providentially crafted the cosmos for our benefit?51

The infinitesimally small probabilities in the microcosm of the gene and the macrocosm of the universe suggest that biology and cosmology are mutually intelligible only if the conditions for human existence were specified in advance by a Creator, who continues to pervade and guide the universe with his presence.



1John Wilford, "Signs of Primitive Life on Mars are Found in Ancient Meteorite," New York Times (August 7, 1996): A1, 11.

2John Pike, Federation of American Scientists, quoted in Newsweek (August 19, 1996): 56.

3Quoted by Frank Drake and Dava Sobel in Is Anyone Out There? The Scientific Search for Extraterrestrial Intelligence (New York: Delacorte Press, 1992), 191.

4Quoted by Kenneth L. Woodward in "A Vindication of God," Newsweek (August 19, 1996): 58.

5John Hedley Brooke, Science and Religion: Some Historical Perspectives (Cambridge: Cambridge University Press, 1991), 62˝3.

6Giordano Bruno, On the Infinite Universe and Worlds (1584), translated by Dorothea Waley Singer, in Giordano Bruno: His Life and Thought (New York: Henry Schuman Publishers, 1950).

7L. Danaeus, The Wonderful Workmanship of the World (London: 1578), 22.

8Brooke, Science and Religion, 97.

9Paul Davies, Are We Alone? Philosophical Implications of the Discovery of Extraterrestrial Life (New York: Basic Books, 1995), 5˝6.

10Brooke, Science and Religion, 105.

11Brooke, Science and Religion, 88˝9.

12Arthur Lovejoy, The Great Chain of Being (Cambridge: Harvard University Press, 1953), 131.

13Robert Jenkin, The Reasonableness and Certainty of the Christian Religion (London, 1700), II, 222.

14Alexander Pope, Essay on Man, Maynard Mack, ed. (New Haven: Yale University Press, 1951), I, lines 23˝28.

15John Ray, The Wisdom of God Manifested in the Work of Creation (11th ed., 1743), 368˝9.

16Percival Lowell, Mars as the Abode of Life (New York: The Macmillan Company, 1908), excerpted by Donald Goldsmith in The Quest for Extraterrestrial Life: A Book of Readings (Mill Valley, CA: University Science Books, 1980), 76˝9.

17David S. McKay, et al., "Search for Past Life on Mars: Possible Relic Biogenic Activity in Martian Meteorite ALH84001," Science 273 (August 16, 1996): 924˝30.

18Drake and Sobel, Is Anyone Out There? 52.

19Ibid., 55˝62.

20Iosef Shklovskii and Carl Sagan, Intelligent Life in the Universe (San Francisco: Holden-Day, 1966), 410˝3.

21Giuseppe Cocconi and Philip Morrison, "Searching for Interstellar Communications," Nature 184 (1959): 844.

22See, for example, Emmanuel Davoust, The Cosmic Waterhole (Cambridge, MA: MIT Press, 1991).

23Frank Drake, "Project Ozma," Physics Today 14 (1961): 40.

24A list of SETI searches is given by Drake and Sobel in Is Anyone Out There? 253˝7.

25Michael H. Hart, "An Explanation for the Absence of Extraterrestrials on Earth," The Quarterly Journal of the Royal Astronomical Society 16 (1975): 128.

26Frank J. Tipler, "Extraterrestrial Intelligent Beings Do Not Exist," Physics Today 34 (April 1981): 9.

27Drake and Sobel, Is Anyone Out There? 140.

28Ibid., 222.

29Michael H. Hart, "Habitable Zones about Main Sequence Stars," Icarus 37 (1979): 351˝7.

30Robert T. Rood and James S. Trefil, Are We Alone? The Possibility of Extraterrestrial Civilizations (New York: Charles Scribner & Sons, 1981), 31˝9, 48˝59.

31Michael H. Hart, "The Evolution of the Atmosphere of the Earth," Icarus 33 (1978): 23˝39.

32William R. Ward, "Comments on the Long-Term Stability of the Earth's Obliquity," Icarus 50 (1982): 444˝8; Jacques Laskar and P. Robutel, "The Chaotic Obliquity of the Planets" and "Stabilization of the Earth's Obliquity by the Moon," Nature 361 (1993): 608˝12, 615˝7.

33Robert Naeye, "OK, Where are They?" Astronomy 24 (July 1996): 37˝43.

34David C. Black, "Other Suns, Other Planets?" Sky and Telescope 92 (August 1996): 20˝7; Robert Naeye, "New Solar Systems," Astronomy 24 (April 1996): 50˝5.

35Michael H. Hart, "Atmospheric Evolution, the Drake Equation, and DNA: Sparse Life in an Infinite Universe," Physical Cosmology and Philosophy, ed. John Leslie (New York: Macmillan, 1990): 256˝66.

36Richard Dawkins, The Blind Watchmaker (New York: W.W. Norton, 1986), Ch. 3; Stuart Kauffman, The Origins of Order (Oxford: Oxford University Press, 1993).

37Hugh Ross, The Creator and the Cosmos (Colorado Springs: NavPress, 1993), 144˝5.

38George Gaylord Simpson, "The Nonprevalence of Humanoids," Science 143 (1964): 769.

39Rood and Trefil, Are We Alone? 80˝96, 122; Hugh Ross, The Creator and the Cosmos, 134.

40Drake and Sobel, Is Anyone Out There? 2.

41Ibid., xii˝xiii.

42Ibid., 160

43Ibid., 160˝2.

44Nancey Murphy, "Jesus and Life on Mars," Christian Century 113 (October 30, 1996): 1028˝9.

45E. A. Milne, Modern Cosmology and the Chrisian Idea of God (Oxford University Press, 1952), 153.

46E. L. Mascall, Christian Theology and Natural Science (New York: Ronald Press, 1956), 37˝9.

47Ibid., 39˝41.

48Paul Tillich, Systematic Theology, Vol. II (Chicago: University of Chicago Press, 1957), 96.

49Carl Sagan, Contact (New York: Simon and Schuster, 1985); Fred Hoyle, The Intelligent Universe (New York: Holt, Rinehart and Winston, 1984).

50Brandon Carter, "Large Number Coincidences and the Anthropic Principle in Cosmology," in M.S. Longair, ed., Confrontation of Cosmological Theories with Observational Data (International Astronomical Union, 1974): 291˝8.

51George Greenstein, The Symbiotic Universe: Life and Mind in the Cosmos (New York: William Morrow and Company, 1988), 27.