DRAFT OF A CHAPTER

 

ARE WE ALONE IN THE UNIVERSE?

Charles P. Poole, Jr.

November 9, 2005; revised June 7, 2006

 

CONTENTS

 

                   1. Introduction

                   2. Is the Universe Pointless

                   3. Inhabitable Planets

                   4. Exocivilizations

                   5. Anthropic Cosmological Principle

                   6. We Are One Genus and One Species

                   7. The Glory of God

 

1. INTRODUCTION

 

          For several centuries there has been an alleged conflict between science and religion. The situation is now much improved since in recent years science has espoused theories that seem generally in conformity with the Christian religion.  Two of the main conflicts during the past century involved Darwinian evolution, and the steady state theory of cosmology.  Modern biology teaches that all human beings belong to the single species Homo sapiens, meaning that they all had a common origin.  Genesis identifies that origin as Adam and Eve.  Modern physics teaches that the entire universe began with a hot, dense concentration of matter and energy confined to a very small volume identified with a singularity, and over the course of fourteen billion years this initial concentration passed through several epochs of growth as it expanded to its present configuration.  Genesis recounts six epochs or days for the creation of the universe.  Thus the overall viewpoints of scientists and theologians are no longer in irreconcilable conflict.   We will comment below on the extent to which they can be considered compatible, or perhaps in harmony, with each other. 

 

          The overall Christian perspective is that the universe was created for human beings because God decided to make man in His image and likeness.   He made planet earth as a home for man, and He made the remainder of the universe as the supporting neighborhood for the earth.  For example, the sun provides the warmth and energy that we need to live.  It seems to me that this is an implied viewpoint of Christianity and other religions.  If we are to attract scientists to accept the Christian faith and worldview we should strive to show that the Christian perspective is in reasonable conformity with the teachings and conclusions of science. 

 

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2. IS THE UNIVERSE POINTLESS?

 

          Nobel Laureate Steven Weinberg reportedly said that “The more the universe is comprehensible, the more it also seems pointless.”  In other words, the universe is so enormous that it does not seem reasonable for an all-knowing or omniscient God to have created it.  We will try to show that the enormity of the universe is not unreasonable. 

 

3. INHABITABLE PLANETS

 

          We live on a relatively minor planet orbiting an average size star located in one of the 100 billion galaxies of the observable universe.  Our galaxy, which is called the Milky Way, contains about 300 billion stars, so the total number of stars in the observable universe is about 30 trillion-trillion (i.e. 30 sextillion or   3x1022),  an unbelievably large number.  The Milky Way galaxy is in the approximate shape of a disc 90,000 light years in diameter and 400 light years in height.  This means that it takes light 90,000 years to travel from one edge of the galaxy to the other side.  The star nearest to Earth, alpha Centauri, is 4.2 light years away, and Andromeda, the nearest spiral galaxy comparable to our own Milky Way, is 2.2 million light years away. 

 

          A light year is a unit of distance corresponding to how far light can travel in a year.   Light moves at the speed of about three 300,000 kilometers a second or 186,000 miles a second, so it can travel a distance of 9.46x1012 kilometers or 5.87x1012 miles in a year. 

 

          For life to be able to develop on a planet, its associated star must satisfy certain criteria.  The star must be large enough to provide sufficient radiation to heat the planet to a reasonably high temperature, and small enough so that it will continue burning for several billion years, to allow time for intelligent life to evolve.  This means that the star should have more than one third of the mass of the sun, and not exceed one and a half times this mass. The planet must move around the star in an almost circular orbit at the proper distance to maintain reasonable climactic conditions without drastic seasonal variations.  The average temperature must sustain abundant water without freezing it or boiling it.  The planet must be large enough so its gravity will hold in place a viable atmosphere.  In 1961 Francis Drake proposed a mathematical equation called the Drake equation which multiplies probabilities for these and other factors to arrive at an estimate of how many stars in the observable universe have planets capable of supporting life. 

 

          Extremely optimistic estimates made using the Drake equation indicate that more than one star in a thousand has such a planet, and very pessimistic estimates suggest that the number is much less than one in many, many billion.  If we make a moderately optimistic assessment that one star in a million has intelligent life then there will be about 300,000 inhabited planets in our galaxy, and the nearest one will most likely be several hundred or several thousand light years away from us.  The total number of inhabited planets in the universe would be three quadrillion or 3x1015, an extremely large number.  If we make the moderately pessimistic estimate that only one star in a trillion has an inhabited planet then life will only be found in 10% of the galaxies, and it is unlikely to exist elsewhere in our own galaxy. There will be ten billion inhabited planets widely distributed throughout the universe.   We would have to travel perhaps ten million light years to reach the nearest civilization.  Finally the most extremely pessimistic estimates that have been made predict that is unlikely for life as we know it to exist elsewhere in the universe. 

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4.  EXOCIVILIZATIONS

 

          If we postulate that God made the universe to populate it with a large number of civilizations, then its vastness does make sense; it no longer needs to be looked upon as pointless.  We will refer to the postulated far away alternate civilizations as exocivilizations.  In fact if this postulate of existing exocivilization is assumed, then the structure of the universe is ideally suited for achieving the end of having many coexisting but noninteracting civilizations.  Perhaps, for example, each galaxy has one planet with intelligent life on it.  In this case there could be no communication since light signals would take several million years to travel from one inhabited planet to its inhabited counterpart in a neighboring galaxy.  Even under the more optimistic assumption mentioned above of 300,000 inhabited planets in our galaxy, it would still take several hundred years for light signals to carry messages back and forth.  Thus even if there are many exocivilizations in our own galaxy, the prospects for meaningful communication with them seem very unlikely.  A signal emitted by one could eventually reach the other, but the reply would take many, many generations to arrive back. 

 

          The possibility of multiple civilizations now in existence raises some theological questions.  How does this possibility fit our traditional beliefs about God and about Jesus, the Son of God. Our concept of a triune God should not be affected by this, but our beliefs concerning the incarnation and the redemption by Christ require careful scrutiny for an exocivilization far away from us.  In such a society God might select a chosen race or tribe to interact with, or adopt some other mechanism for making Himself and His wishes manifest.  There might be a fallen nature and a redeemed nature associated with the civilization.  All of these suggestions are, of course, pure speculation, but entertaining them serves to make the vastness of the universe seem less pointless, and the universality of many Christian values seem more cogent. 

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5.  ANTHROPIC COSMOLOGICAL PRINCIPLE

 

          Until the invention of the telescope there was a belief common to mankind that human beings have a privileged position in the Universe.  When Galileo looked through his telescope and found that the planet Jupiter had moons which also cycled through phases such as new moon, first quarter, full moon, and last quarter, the planet Earth no longer seemed  so privileged.  Astronomers, other scientists, and soon academia adopted the world view or Copernican Principle that Man does not occupy a privileged position in the Universe.  This idea remained dominant until the last few decades of the twentieth century when some cosmologists began to wonder to what extent we as intelligent observers are related somehow to the type of description that we offer, and the conclusions that we arrive at, concerning the nature of the universe.  In 1974 Brandon Carter suggested that the Copernican Principle is not absolute, but should be limited by an Anthropic Principle which states that "our location in the Universe is necessarily privileged to the extent of being compatible with our existence as observers."  In other words, since observers are offering a description of the Universe, it follows that the Universe which they describe must have had the capability of evolving intelligent life so that these observations could be made and reported.  Thus conditions close enough to the region of observation must have been suitable for the development of biological evolution leading to the appearance of man. 

 

          More specifically Barrow and Tipler proposed the anthropic principle that is discussed in Chap. xx.  All physical and cosmological quantities, such as the charge on the electron and strength of gravity, have values restricted by the requirement that there exist sites where carbon-based life can evolve, and by the further requirement that the Universe is old enough for life to have already evolved.  The physical universe was created to be compatible with the eventual presence of life, including human life, for a duration exceeding several centuries.  A more theistic conclusion is that the universe was created for Man to inhabit a small region of it. 

 

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6.  WE ARE ONE GENUS AND ONE SPECIES

 

          It is a standard Christian belief that we are all descended from common ancestors, namely Adam and Eve.   This is in conformity with what is known biologically, namely that all human beings belong to the single species sapiens in the genus Homo.  The family Hominidae has two other genera besides Homo, namely Australopithecus and Ramapithecus, and the genus Homo has two other species, namely Homo erectus and Homo habilis, so biologically man has some close relatives in the fossil record, but none have survived to the present.  The order Primates comprises eleven families and a large number of genera and species, so there are many distant relatives of Homo sapiens such as apes and chimpanzees that are living today, but no biologically close ones.  Man is biologically unique, in conformity with Genesis. 

 

7.  THE GLORY OF GOD

 

          The more traditional view of why the universe is so huge is based on Psalm 119:1 “The heavens declare the glory of God and sky proclaims its builder's craft.” This is quoted in Greek in the preface to the third edition of Classical Mechanics which I coauthored with Herbert Goldstein and John Safko. The larger the Universe, is the greater the glory that is given to God.  From the viewpoint of humans, the universe is so huge that an even larger one would not seem more remarkable.  Human beings cannot really comprehend or appreciate such an enormity.  It seems to me that a huge universe populated by hundreds of thousands of widely separated civilizations of intelligent life gives even more glory to God than a vast uninhabited, seemly pointless, universe. 

 

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