If we follow the hypothesis of the biochemist Dr S Miller, life and the conditions essential for life may have developed more quickly on some of these planets than on Earth. If we accept this daring assumption, civilisations more advanced than our own could have developed on 100,000 planets.
Professor Dr Willy Ley, the well-known scientific writer and friend of Wernher von Braun, told me in New York: 'The estimated number of stars in our Milky Way alone amounts to 30 milliards. The assumption that our Milky Way contains at least 18 milliard planetary systems is considered admissible by present-day astronomers. If we now try to reduce the figures in question as much as possible and assume that the distances between planetary systems are so regulated that only in one case in a hundred does a planet orbit in the ecosphere of its own sun, that still leaves 180 million planets capable of supporting life. If we further assume that only one planet in a hundred that might support life actually does so, we should still have the figure of 1-8 million planets with life. Let us further suppose that out of every hundred planets with life there is one on which creatures with the same level of intelligence as homo sapiens live. Then even this last supposition gives our 'Milky Way the vast number of 18,000 inhabited planets.'
Since the latest counts give 100 milliard fixed stars in our Milky Way, probability indicates an incomparably higher figure than Professor Ley puts forward in his cautious calculation.
Without quoting Utopian figures or taking unknown galaxies into account, we may surmise that there are 18,000 planets comparatively close to the earth with conditions essential to life similar to those of our own planet. Yet we can go even further and speculate that if only 1 per cent of these 18,000 planets were actually inhabited, there would still be 180 left!
There is no doubt about the existence of planets similar to the earth-with a similar mixture of atmospheric gases, similar gravity, similar flora and possibly even similar fauna. But is it even essential for the planets that support life to have conditions similar to the earth's?
The idea that life can only flourish under terrestrial conditions has been made obsolete by research. It is a mistake to believe that life cannot exist without water and oxygen. Even on our own earth there are forms of life that need no oxygen. They are called anaerobic bacteria. A given amount of oxygen acts like poison on them. Why should there not be higher forms of life that do not need oxygen?
Under the pressure of the new knowledge that is being acquired every day we shall have to bring our mental world picture up to date. Scientific investigation, concentrated on our earth until very recently; has praised this world of ours as the ideal planet. It is not too hot and not too cold; it has plenty of water; there are unlimited quantities of oxygen; organic processes constantly rejuvenate nature.
In fact, the assumption that life can only exist and develop on a planet like the earth is untenable. It is estimated that two million different species of living creatures live on the earth. Of these—this again is an estimate—1-2 millions are 'known' scientifically. And among these forms of life known to science there are still a few thousand that ought not to be able to live at all according to current ideas! The premises for life must be thought out and tested anew.
For example, one would think that highly radioactive water would be free from germs. But there are actually some kinds of bacteria which can adapt themselves to the lethal water that surrounds nuclear reactors. An experiment carried out by the scientist Dr Siegel sounds eery. He recreated the atmospheric conditions of Jupiter in his laboratory and bred bacteria and mites in this atmosphere, which shares none of the prerequisites we have hitherto laid down for 'life'. Ammonia, methane and hydrogen did not kill them. The experiments by Hinton and Blum, the Bristol University entomologists, had equally startling results. The two scientists dried a species of midge for several hours at a temperature of 100° C. Immediately afterwards they immersed their 'guinea pigs' in liquid helium, which, as is well known, is as cold as space. After heavy irradiation they returned the midges to their normal living conditions. The insects continued their biological vital functions and produced perfectly 'healthy' midges. We also know of bacteria that live in volcanoes, of others that eat stone and some that produce iron. The forest of question marks grows.
Experiments are going on at many research centres. New proofs that life is by no means bound to the prerequisites for life on our planet are constantly accumulating. For centuries the world appeared to revolve around the laws and conditions that govern life on earth. This conviction distorted and blurred our way of looking at things; it put blinkers on scientific investigators, who unhesitatingly accepted our standards and systems of thought when viewing the universe. Teilhard de Chardin, the epoch-making thinker, suggested that only the fantastic has a chance of being real in the cosmos!
If our way of thinking worked the other way round, it would mean that intelligences on another planet took their living conditions as a criterion. If they lived at temperatures of minus 150-200° C, they would mink that those temperatures, which are destructive to life as we know it, were essential for life on other planets. That would match up to the logic with which we are trying to illuminate the darkness of our past.
We owe it to our self-respect to be rational and objective. At some time or other every daring theory seemed to be a Utopia. How many Utopias have long since become everyday realities! Of course the examples given here are meant to point out the most far-fetched possibilities. Yet once the improbable things that we cannot even conceive of today are shown to be true, as they will be, barriers will fall allowing free access to the impossibilities the cosmos still conceals. Future generations will find all kinds of life that have never been dreamt of in the universe. Even if we are not there to see it, they will have to accept the fact that they are not the only, and certainly not the oldest, intelligences in the cosmos.
The universe is estimated to be between eight and twelve milliard years old. Meteorites bring traces of organic matter under our microscopes. Bacteria millions of years old awake to new life. Floating spores impelled by the light of a sun traverse the universe and at some time or other are captured by the gravitational field of a planet. New life has gone on developing in the perpetual cycle of creation for millions of years. Innumerable careful examinations of all kinds of stones in all parts of the world prove that the earth's crust was formed about 4,000 million years ago. Yes, and all that science knows is that something like man existed a million years ago! And out of that gigantic river of time it has only managed to dam up a tiny rivulet of 7,000 years of human history, at the cost of a lot of hard work, many adventures and a great deal of curiosity. But what are 7,000 years of human history compared with thousands of millions of years of the history of the universe?
We—the paragons of creation?—took 400,000 years to reach our present state and our present stature. Who can produce concrete proof to show why another planet should not have provided more favourable conditions for the development of other or similar intelligences? Is there any reason why we may not have 'competitors' on another planet who are equal or superior to us? Are we entitled to discard this possibility? We have done so up to the present.
How often the pillars of our wisdom have crumbled into dust! Hundreds and hundreds of generations thought that the earth was flat. The iron law that the sun went round the earth held good for thousands of years. We are still convinced that our earth is the centre of everything, although it has been proved that the earth is an ordinary star of insignificant size, 30,000 light years from the centre of the Milky Way.
The time has come for us to admit our insignificance by making discoveries in the infinite unexplored cosmos. Only then shall we realise that we are nothing but ants in the vast State of the universe. And yet our future and our opportunities lie in the universe, where the gods promised they would.
