C7: Aliens

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Introduction

As we near the end of the twentieth century it is becoming increasingly likely that we are not alone. Some of those stars that fill the night sky probably shine down on planets which are inhabited by other life forms which we have never seen. Looking at both scientific information and human experience, this chapter reviews the evidence and implications of extraterrestrial life and suggests why people are so fascinated by the possibility of its existence.

Scientific background

LIFE: What are the chances that life exists on other planets? In our galaxy, the Milky Way, there are over 100 billion stars of comparable size to our Sun. Ours is just one of billions of galaxies in the known universe containing, all told, more than 10^20 (a one followed by twenty zeros) stars. Like our sun, millions of these stars have planets orbiting them. If only one star in a hundred has orbiting planets, of which one in a hundred are earthlike, of which one in a hundred are of the right temperature, and of which one in a hundred have a chemistry similar to that on Earth, then there are still well over ten billion planets suitable for organic life. You really have to ask the question: what is the probability that life only exists on Earth?

CONTACT: Carl Sagan, the famous Harvard astronomer, believed that there are about one billion planets in our galaxy alone to have developed advanced civilizations. Cambridge University's distinguished cosmologist Sir Fred Hoyle speculates that an interchange of messages between planets of different solar systems is going on, on a vast scale, all the time, and that we are naively unaware of it. He said: "My guess is that there might be a million or more subscribers to the galactic directory. Our problem is to get our name into that directory."

EXOBIOLOGY: The predominant scientific view is that the development of any form of life is quite natural given suitable conditions and is not at all unique to Earth. Thus the probability of rational intelligent beings on a planet other than Earth is no longer fantastic. 'Exobiology,' the study of forms of extraterrestrial life, is a field growing in size and respectability.

Iffy UFOlogy?

To mainstream scientists, UFOlogy remains a pseudo-science. It is plagued by fraudulent reports, forgeries and unreliable witnesses. But you don't have to be a crackpot to belive in UFOs. The DNA code-cracker and Nobel prize winner Francis Crick's last book, 'Life Itself,' argues that DNA was brought down to earth by a rocket from another planet, and there are other respectable scientists have similiar theories. As yet, there is no firm proof to support anyone's theory.

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