IS THE LIFE ON THE OTHER WORLDS?^ 



By Sib James Jeans, O. M., D. Sc, LL. D., F. R. S., M. R. I. 



Profcsftor of Astronotny 

 Royal Institution of Great Britain 



So long as the earth was believed to be the center of the universe 

 the question of life on other worlds could hardly arise ; there were no 

 other worlds in the astronomical sense, although a heaven above and 

 a hell beneath might form adjuncts to this world. The cosmology of 

 the "Divina Commedia" is typical of its period. In 1440 we find 

 Nicholas of Cusa comparing our earth, as Pythagoras had done before 

 him, to the other stars, although without expressing any opinion as 

 to whether these other stars were inhabited or not. At the end of the 

 next century Giordano Bruno wrote that "there are endless particular 

 M'orlds similar to this of the earth." He plainly supposed these othei- 

 worlds — "the moon, planets and other stars, which are infinite in 

 number" — to be inhabited, since he regarded their creation as evidence 

 of the Divine goodness. He was burned at the stake in 1600; had 

 he lived only 10 years longer, his convictions would have been 

 strengthened by Galileo's discovery of mountains and supposed seas 

 on the moon. 



The arguments of Kepler and Newton led to a general recognition 

 that the stars were not other worlds like our earth but other suns 

 like our sun. When once this was accepted it became natural to 

 imagine that they also were surrounded by planets and to picture each 

 sun as showering life-sustaining light and heat on inhabitants more or 

 less like ourselves. In 1829 a New York newspaper scored a great 

 journalistic hit by giving a vivid, but wholly fictitious, account of 

 the activities of the inhabitants of the moon as seen through the 

 telescope recently erected by His Majesty's Government at the Cape. 



It will be a long time before we could see what the New York paper 

 claimed to see on the moon — batlike men flying through the air and 

 inhabiting houses in trees — even if it were there to see. To see an 

 object of human size on the moon in detail we should need a tele- 

 scope of from 10,000 to a 100,000 inches aperture, and even then we 

 should have to wait years, or more probably centuries, before the air 

 was still and clear enough for us to see details of human size. 



'Afternoon lecture, Thursday, November 20, 1941. Reprinted by permission from the 

 Proceedings of the Royal Institution of Great Britain, 1941. 



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