NINETEENTH CENTURY DEVELOPMENTS 5I 



supporters of the theory under discussion as being the only 

 possible explanation of the appearance of life on our planet. 

 But before this hypothesis is scientifically admissible it must 

 be shown that life is widely distributed throughout the uni- 

 verse, that it is to be found, not only on the Earth or within 

 the solar system, but also in other parts of the universe. 

 Furthermore, it is necessary to explain how the germs of life 

 could be transferred to the Earth through interplanetary and 

 interstellar space while remaining alive and able, under 

 favourable circumstances, to grow and give rise to a new 

 race of living things. 



The bold suggestion that there might be a multiplicity of 

 worlds inhabited by living creatures was very clearly stated 

 by the great sixteenth century scientist Giordano Bruno. In 

 his treatise Del' infinito universo e mondi^^ he wrote, " There 

 exist innumerable suns and innumerable earths circling 

 round their suns just as our seven planets circle round our 

 Sun. Living things dwell on these worlds." 



For a long time this idea did not spread far because it 

 came up against the ancient but very active anthropocentric 

 conviction that there is only one earth supporting life in the 

 universe. It was considered daring and fantastic for a scien- 

 tist to think that there might be many inhabited worlds. 

 It is only 15-20 years since the authoritative English astrono- 

 mer Sir James Jeans^" stated that 



We know of no type of astronomical body in which the condi- 

 tions can be favourable to life except planets like our own 

 revolving round a sun. . . . Yet exact mathematical analysis 

 shows that planets cannot be born except when two stars pass 

 within about three diameters of one another. . . . The calculation 

 shows that even after a star has lived its life of millions and 

 millions of years the chance is still about a hundred thousand to 

 one against its being a sun surrounded by planets. . . . All this 

 suggests that only an infinitesimally small corner of the universe 

 can be in the least suited to form an abode of life. 



Now, however, we cannot accept Jeans' point of view. 

 On the contrary, contemporary scientific findings definitely 

 confirm the inspired foresight of Bruno. In 1938 the Swedish 

 astronomer E. Holmberg^^ made careful analyses of a number 



