The God Of The Extra-Terrestrials


Vatican Observatory

Life in the Universe

Evolution is an intrinsic and proper characteristic of the universe. Neither the universe as a whole nor any of its ingredients can be understood except in terms of evolution. And evolution is a daily happening. We, for instance, are constantly exchanging atoms with the total reservoir of atoms in the universe. Each year 98% of the atoms in our bodies are renewed. Each time we breath we take in billions and billions of atoms recycled by the rest of breathing organisms during the past few weeks. Nothing in my genes was present a year ago. It is all new, regenerated from the available energy and matter in the universe. My skin is renewed each month and my liver each six weeks. In brief, human beings are among the most recycled beings in the universe.

Life has made a relatively late appearance considering the total age of the universe. Life is thought to have emerged about three billion (3 x 109) years ago in its first microscopic forms. This was about eleven billion years after the Big Bang and about six billion years after the formation of the first stars. Why did it take so long for life to emerge? In order to provide the chemical abundances required for life it is estimated that three generations of stars were required. It is only through nucleosynthesis in stellar interiors that the heavier elements can be created and at the death of a star this material is regurgitated to form the matrix for a new generation of stars. The lifetime of a star depends upon its total mass and can vary from several millions of years for a very massive star to tens of billions of years for lower mass stars. At any rate it took about ten billion years of stellar evolution to produce carbon, nitrogen, oxygen, etc. I repeat that the universe is by its nature evolutionary and it had to evolve to be big and old before it could contain us. I was tempted to say, ‘in order to contain us,’ but that would have introduced a finality which may not be justified scientifically.

The question is further complicated by the following consideration. As the universe evolved the appearance of life required a very fine tuning of the various constants of nature and the laws whereby the universe applies those constants. Let me give a few examples. If the velocity of expansion of the universe at its beginning were one millionth greater or smaller than it was, we would not be here, because the universe would either have expanded so fast that no complex systems could come to be or it would have almost immediately collapsed in upon itself. If the mass of the proton and the electron differed by an extremely small amount, we would not be here, because stars like the sun would not have stable enough energy mechanisms to provide for the long time required to generate the chemical abundances necessary for life. If the energy level of the carbon molecule, which is created by two nuclear reactions beginning with four helium atoms, were only slightly less than it is, the abundance of carbon in the universe would be millions of times less than it is and totally inadequate to provide the chemical processes which led to life. Now all the constants of nature, a few examples of which I have just mentioned, are empirical values, discovered as it were in a laboratory. They could have different values and, if they did, we would not be here. Would you allow me to ask as a scientist: WHY are we here? To the best of my knowledge, no satisfactory scientific explanation has been given for this fine tuning of the universe. Life in the universe is a marvel; its origins are not completely understood scientifically.

Chance or Necessity?

Did the fine tuning of the universe and the consequent emergence of life happen by chance? The calculated probability is extremely small and not acceptable as a scientific answer. Granted that pure chance is not a satisfactory explanation, we might still ask to what extent chance played a role. The religious inclinations of Albert Einstein are not well understood. In his physics, however, he was clearly deterministic. In the debate over the meaning of quantum mechanical indeterminism he claimed that God does not play with dice. Recently an eminent biochemist has replied: Yes he does, because he is certain to win. In attempting to frame his conclusion in the context of Einstein’s statement, what he was actually claiming is that intrinsic to the universe there is an interplay of determinism, chance and opportunity. His response to Einstein was to state that it is in the very nature of the universe that intelligent life inevitably come to be, although a long and complicated process involving laws, chance happenings and propitious opportunities was required. The important new consideration here is the notion of ‘opportunity.’ Neither chance nor necessity will succeed without it.

It appears to me that this state of affairs in our current knowledge of the universe and our place in it is an invitation to proceed beyond strictly scientific considerations to more transcendental considerations. The invitation, I would propose, comes from science. The ultimate answer to the ‘why’ almost certainly will not.

Finally, it appears to me that, if we accept the invitation offered by this new scientific conception of the intrinsic struggles of the universe to realize itself in self-reflecting beings, we have a new way of using the process of analogy to come to a richer understanding of God through his creation. In our own personal freedom we participate in God’s freedom. In an analogous way God has made the universe free. In its struggle to become it reflects God’s loveliness, his tender care to allow us to be what we will be and in a universe which is always becoming what it will become.

The God of Extra-Terrestrials

In his Metaphysics Aristotle states:

It is owing to their wonder that men first began to philosophize; they wondered originally at the obvious, and then they advanced little by little to the greater matters, about the phenomena of the moon and those of the sun and the stars. (Metaphysics II, 2)

Immanuel Kant likewise stated:

Two things fill the mind with ever new and increasing admiration and awe: the starry heavens above and the moral law within. (Critique of Practical Reason)

Enrico Fermi recalls that one night while sitting under the stars he overheard a group of farmers nearby and remembers a robust voice stating:

What a nice sky! How can some people say that God does not exist? (Responsibilità del Sapere 31 [1979] 21-23)

The thoughts or reports of these three eminent personages reveal the almost inevitable link in people’s minds between the exploration of the Universe and thoughts about God. Based upon that link this paper proposes one specific area in which science confronts religious thought in the Christian tradition with a challenge. To that purpose ‘many worlds’ refers herein to ‘intelligent civilizations’; thus ‘world’ is used as it is in such phrases as ‘world history,’ ‘World War II’ etc. There is no intention to speak of ‘many universes’ as cosmologists do, for instance, in their theories of an inflationary universe.

Too often discussions of the relationship between science and religion are carried out in very general terms. Such discourse can be quite unfruitful for two reasons:

1. As compared to the natural sciences religion contains a larger measure of the subjective, of human experiences not totally verifiable by objective reasons. Such subjective experiences are not, of course, limited to religion. They are present in many areas of our lives. Nor need these experiences, religious or otherwise, necessarily conflict with reason. They simply are not limited to rational explanation. They go beyond what can be rationally justified.

2. While for the natural sciences we have a rather acceptable idea of what we mean by science, the very notion of religion is ill-defined. Does it mean worship? Does it mean being a ‘good person’? Does it mean accepting certain moral dictates that go beyond what is commonly accepted as good and bad? Does it mean accepting those dictates out of personal conviction or out of loyalty to a certain tradition? Does it mean believing in certain doctrines? Does it mean accepting a certain authoritative and hierarchical structure, i.e. being affiliated with a certain Church? To most of us religion would imply more of an affirmative than a negative answer to all of the above. And yet the situation is further complicated by the multiplicity of religions which differ among themselves, have even warred among themselves, over the responses given to such questions as the above. Even today, if we look at some of the main religious traditions: Islam, Judaism, Christianity, Buddhism, etc., we see not only vast differences among them, but enormous divisions within any one of the traditions.

The only way, therefore, that dialogue as a rational experience can take place is that, on the part of religion, the dialogue be limited to the rational foundations for religious belief. Even then, the only way that any such dialogue could have universal significance is that we could assume that there existed common rational foundations across all religious traditions and that is simply not the case. It seems, therefore, that any fruitful dialogue requires that the rational basis for certain specific religious beliefs in certain specific religious traditions be confronted with what is known from the natural sciences.

What is known from the natural sciences about ‘many worlds,’ i.e., extra-terrestrial life? We have rather good models for the formation of planets about solar-like stars. A large interstellar cloud, typically containing 103 masses of the sun, fragments due to an interplay of kinetic, gravitational and magnetic energy. Each fragment that is sufficiently compact and stable begins to collapse by self-gravity and, like any normal gas, as it collapses it heats up. If it is sufficiently massive (more than about 0.1 the mass of the sun), it will raise the temperature in its interior sufficiently high, so that thermonuclear burning begins. At this point a star is born. The sun was born in this way and will keeping shining as it does today for about five billion years when it will explode and become a white dwarf. In the course of the cloud collapse there are stages which are important for the formation of a planetary system. As the star collapses, in order to conserve angular momentum, it rotates and this rotation causes a continuous flattening of the cloud until at the end of 107 years a disk has formed. There is also an intermediate stage after about 105 years at which a wind of high energy particles sweeps through the cloud and carries away much of the material left over from the collapse.

So, we have a solar-like star with a rotating disk of hydrogen gas and dust about it. How do planets form within this disk? As the disk continues to rotate the material in it begins to separate out into rings according to the mass distribution. Within each ring conglomerates begin to form due to elastic collisions, gravity and electrostatic binding. Eventually larger conglomerates, called planetesimals, of the order of 100 km in extent are formed and then from these the planets are formed. During these processes the lighter elements are preferentially driven to the outer parts of the disk due to temperature of the parent star and the stellar wind. This explains why the outer planets in the solar system are more gaseous than the inner planets. Thus, for a star like the sun we have after about 109 years a stable star with a planetary system about it.

How plausible is the model described above? Let us compare what we predict with what we observe. When we examine the distribution of stars, according to their temperature and mass in our own Galaxy and in other galaxies, the model proposed for the formation of stars, appears to be reasonable. And when we determine the ages of stars and of galaxies by methods independent of the assumptions made in the above model of star formation, it all appears to be consistent. Even our knowledge of elementary particle physics, a totally independent field of research, supports what we have said about the thermonuclear processes in stars. So, our models for star formation appear to be consistent with what we observe.

Have we observed planets? Only in the past decade have we been able to develop the sophisticated techniques required to discover planets about other stars. We have now discovered more than one hundred of such planets. These planets have been discovered by analyzing the systematic oscillations in the motion of the parent star. Only massive planets near to their parent star can be discovered in this way. Jupiter, for instance, could not be detected in this way from the nearest star to the Sun. So, the method is very limited. In no case, have we detected an Earth-like planet.

Other techniques, such as high-resolution imaging in space and from the Earth, spectroscopic detection of extra-solar planetary atmospheres. etc, are being developed. Within the next decade we will undoubtedly discover hundreds of candidates as extra-solar planets.

We may also, based upon observations and our knowledge of the formation of planets and stars, pose some convincing statistical considerations. Since there are about 1011 stars in the Galaxy and 1011 galaxies in the universe, there are 1022stars in the universe. From our knowledge of the distribution of stars by mass in the Galaxy, we can estimate that about 30% of stars are solar-like. It would be difficult to estimate the percentage of solar-like stars that would have developed a planetary system, but from our knowledge of the formation of the solar system we know that the probability is neither zero nor one hundred percent. Let us say it is 10%. How many of these planets would be like the Earth: its mass, distance from the Sun, an atmosphere, etc. This may be even more uncertain, but, again, from geological knowledge of the formation of the atmosphere, we know that there is a finite probability. Let us say it is 2%. Now, if we put all of these considerations together we have, from these statistical considerations, 1017 Earth-like planets in the universe.

It is important to note the nature of this conclusion. It is based upon scientific facts combined with reasonable estimates which are themselves based upon scientific facts. Unless our scientific thinking is drastically wrong, this conclusion is acceptable and merits our further considerations about what it implies. I take it to mean at a minimum that the macroscopic physical conditions for life (an earth-like planet in a ‘habitable zone’ about a solar-like star) exist elsewhere in the universe. We must also note that we have not spoken of extra-terrestrial life nor even directly of the conditions for extra-terrestrial life. Indirectly, however, we cannot ignore the question: if there is this degree of statistical certainty and at least some modest observational evidence that extra-terrestrial earths exist, is there extra-terrestrial life? While, for various reasons, it is impossible here to address that question directly, the very asking has religious implications which we will soon discuss. One of the principal reasons for the lack of any direct approach to the question of extra-terrestrial life is the great uncertainty that still exists among geologists and biologists as to our scientific knowledge of the origins of life on the Earth. Lacking that knowledge, we can only speak directly of the macroscopic physical conditions for extra-terrestrial life and of what religious considerations are implied.

And now to the specific question about extra-terrestrials. If there is intelligent life elsewhere, did Christ come to save them? This is the least scientific of my ramblings thus far, so please permit a somewhat abrupt change in literary style. Let us return to the thoughts of Aristotle, Kant and Enrico Fermi’s farmer. Please note a progression from Aristotle’s philosophizing to Kant’s moralizing to the God of Fermi’s farmer. While all three intellectual experiences are intimately linked, they are distinct and, with your indulgence, I have made a choice to talk about God only, and, indeed, about the God of Fermi’s farmer. I do this because there is no doubt that the experience of Fermi’s farmer is the most common one and, in my mind, the truest one. So I will not philosophize and I will certainly not enter into the mine field of ethics, of what is right and wrong. I wish simply to say a few things about what farmers think about God in view of what cosmologists think about life in the universe.

Does it make sense to think that there might be other intelligent beings in the observable universe, other than the few we meet on the surface of the Earth? Yes, if we emphasize the word MIGHT, then it makes eminent sense to think of extra-terrestrial intelligent life (ETs). In fact, from the discussion above about the formation of planetary systems, it would be nonsense from a scientific point of view to deny the possibility of ETs. So let us muse about what a religious person thinks about God when she/he knows very well that there could be other persons on other planets about other stars also thinking about God. Again I beg your indulgence if we speak in the context of Christianity, although our musings will be common to all monotheistic religions, with some, at least at this stage of our thinking, insignificant differences.

How can there be human beings elsewhere in the universe? After all God sent his only son, Jesus Christ, true God and true man to this Earth. He was born in Bethlehem, he lived in Nazareth, and he was crucified on Calvary, outside Jerusalem. And God had only one Son. Now how could God send his only Son, who is truly a man, to other planets. Can a man exist on many different planets? But maybe Jesus did not have to arrive on other planets even though there are people with souls there. The farmer knows his religion very well, so his musings are very incisive and, after listening to them for a long time, we are able to piece together the following sequence of hypotheses about the religious consequences of there being intelligent beings elsewhere.

Human beings have bodies which came forth after about 11 billion years in an evolving universe. Those bodies are very complex totalities, but most of all the human brain is the most complex organism we know. As a consequence human beings are intelligent, they can know themselves knowing and so they have a soul, a spiritual reality, and as such they were made by God. Are there other such beings, made by God, on other planets? We come to our first hypothesis. Yes, by assumption, we will call them by their traditional name of ETs.

At the very beginning human beings did something bad. They revolted against the God who had made them. Theologians call this ‘original sin.’ Even if we do not accept the Scripture story of Adam and Eve as historically true, ‘original sin’ is an essential element in the theologians view of the relationship of humans to God. Did our ETs sin in this way? We come to our second hypothesis and, in order to keep the discussion going, we, of course, answer ‘yes, they sinned.’ Note that our second hypothesis is very different from the first. That we sinned is an historical fact and, therefore, quite contingent. It might not have happened. Whereas, ETs existing at all is not quite so contingent. In fact, many scientists maintain that, if life came to be at all, it MUST have come to be prolifically in this universe. There is a kind of necessity, although not absolute, about there being ETs.

God freely chose to redeem human beings from their sin. Did he do this also for ETs? Now we are getting ever more hypothetical, since we are determining what God, who is absolutely free, would freely choose to do. In fact, there are serious theological implications here for our understanding of God. With Fermi’s farmer, who senses that God is good and passionate, the answer is ‘yes, God did save them.’ How could he be God and leave ETs in their sin? After all he was good to us. Why should he not be good to them? With the farmer we are struggling to justify our hypothesis, but we accept it not realizing that matters are going to get more difficult as we proceed.

God chose a very specific way to redeem human beings. He sent his only Son, Jesus, to them and Jesus gave up his life so that human beings would be saved from their sin. Did God do this for ETs? Or did he chose another way to redeem ETs? The theological implications about God are getting ever more serious. Surely God is completely free to chose his methods. He certainly did not have to send his Son to us. But once he chose to do so, did he have to chose to redeem ETs in the same way. There is deeply embedded in Christian theology, throughout the Old and New Testament but especially in St. Paul and in St. John the Evangelist, the notion of the universality of God’s redemption and even the notion that all of creation, even the inanimate, participates in some way in his redemption. In his own way Fermi’s farmer realizes this and so he concludes that, if God is truly the God we know from how he revealed himself to us, then ‘yes, he sent his only Son to redeem ETs.’

After this whole sequence of hypotheses, increasingly more difficult to make, we come to a serious responsibility to rethink some fundamental realities within the context of religious belief. What is the human being? Could Jesus Christ, fully a human being, exist on more than one planet at more than one time? We are obviously very limited today in our ability to answer such questions. We cannot rely, even theologically, solely upon God’s revelation to us in the Scriptures and in the Churches, since that revelation was TO US and was received, therefore, in a very anthropocentric sense. We have come a long way since God revealed himself to us in a special way. And so, even theologians, if they are as wise as Fermi’s farmer, must learn from the best of science, both the life sciences and the physical sciences, because they are an important ingredient in our continuing search to understand ourselves in God’s universe.

In our age, perhaps more than at any other time, the scientific view of the world has been the principal spur to a more unified view of the world. It has opened our minds to the vast richness of the universe which cannot be appropriated by any one discipline alone. Science invites us to that vision. It also cautions us not to absolutize scientific results. The religious person must beware of a serious temptation of the cosmologists. Within their culture God is essentially, if not exclusively, seen as an explanation and not as a person. God is the ideal mathematical structure, the theory of everything. God is Mind. It must remain a firm tenet of the reflecting religious person that God is more than that and that God’s revelation of himself in time is more than a communication of information. Even if we discover the ‘Mind of God,’ the religious person may still claim that we will not have thereby necessarily found God. Dialogue requires that we accept these diverse ways of viewing our experiences.

In his Dialogue Concerning Two Chief World Systems, for which he was condemned, Galileo presents among other conversations an exquisite exchange between Salviati, the champion of Copernicanism, and Simplicius, the doubter and implied simpleton (see Galileo Galilei, Dialogue Concerning Two Chief World Systems, trans. Stillman Drake [Berkeley: University of California Press, 1953] 367-368). Simplicius claims that a serious objection to Copernicanism is that no stellar parallax has been detected. This is a very weighty argument indeed. But Salviati replies that the stars may be so distant from the Earth that it is not possible to detect their parallax. Salviati’s argument would require that even the nearest stars be tens of light years away. Simplicius, having made that rough calculation, philosophizes that such great spaces would be ‘superfluous and vain’ and of no use whatsoever to the human race. Salviati replies that God might indeed have other plans in mind than being exclusively involved in taking care of human beings and that ‘it is brash for our feebleness to attempt to judge the reasons for God’s actions.’ It appears that this is still a good attitude to have. While searching for rational explanations of how to confront the possibility of ETs with certain religious beliefs, we must remain open to the religious experience of God’s mysterious ways.


George Vincent Coyne, SJ (1933-2020) was an American Jesuit priest and astronomer. Fr Coyne became Director of the Vatican Observatory in 1978, and also Associate Director of the UA Steward Observatory. During 1979-80 he served as Acting Director and Head of the UA Steward Observatory and the Astronomy Department. As Director of the Vatican Observatory, he was a driving force in several new educational and research initiatives. He spent five months of the year in Tucson as adjunct professor in the University of Arizona Astronomy Department.

From January 2012 until his death, he taught at Le Moyne College in Syracuse, New York. His career was dedicated to the reconciliation of theology and science, while his stance on scripture was absolute: ‘One thing the Bible is not,’ he said in 1994, ‘is a scientific textbook. Scripture is made up of myth, of poetry, of history. But it is simply not teaching science.’

Fr Coyne was invited to the Pari Center on November 25, 2004 to give a talk as part of the Metanexus Local Initiatives Program: Dialogues on Religion and Science. His talk was entitled ‘Scienza e Fede: I limiti e le speranze’ (Science and Faith: The Limits and Hopes.)