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Is it conceivable that we world citizens of the twentieth century are not the only living beings of our kind in the cosmos? Because there is no homunculus from another star on display in a museum for us to visit, the answer ‘Our earth is the only star with human beings' still seems to be legitimate and convincing. But the forest of question marks grows and grows as soon as we make a careful study of the fact resulting from the latest discoveries and research work. On a clear night the naked eye can see about 4,500 stars, so the astronomers say. The telescope of even a small observatory makes nearly two million stars visible and a modern reflecting telescope brings the light from thousands of millions more to the viewer-specks of light in the Milky Way. But in the colossal dimensions of the cosmos our stellar system is only a tiny part of an incomparably larger stellar system-of a cluster of Milky Ways, one might say, containing some twenty galaxies within a radius of 1 1/2 million light years (1 light year = the distance travelled by light in a year, i.e. 186,000 x 60 x 24 x 365 miles). And even this vast number of stars is small in comparison with the many thousands of spiral Nebulae disclosed by the electronic telescope. Disclosed up to the present day, I should emphasise, for research of this kind is only just beginning. The astronomer Harlow Shapley estimates that there are some 10 <20> stars within the range of our telescopes. When Shapley associates a planetary system with only one in a thousand stars, we may assume that it is a very cautious estimate. If we continue to speculate on the basis of this estimate and suspect the necessary conditions for life on only one star in a thousand, this calculation still gives a figure of 10 <14>. Shapley asks: how many stars in this truly ‘astronomical’ figure have an atmosphere suitable for life? One in a thousand? That would still leave the incredible figure of 10 <11> stars with the prerequisites for life. Even if we assume that only every thousandth planet out of this figure has produced life, there are still 100 million planets on which we can speculate that life exists. This calculation is based on telescopes using the techniques available today, but we must not forget that 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. Chapter One - Are There Intelligent Beings In The Cosmos? these are constantly being improved.