THE WIDER ASPECTS OF COSMOGONY ' 



By J. II. Jeans, Sec. K. S. 



[With three plates] 



Interest in scientific cosmogony is a recent and still a very tender 

 growth. Anthropologists and geologists tell us that man has 

 existed on earth for something like 300,000 years; we must go this 

 far back to meet our apelike ancestry. Between them and us some 

 10,000 generations of men have walked the earth, most of w^hom have 

 probably given some thought, in varying degree, to the significance 

 of their existence and the plan of the universe. 



Of these 10,000 generations of men, the first 9,990 unhesitatingly 

 regarded the earth as the center, and terrestrial life as the central 

 fact, of the universe. As was suited to its majesty and dignity as 

 the abode of man, the earth stood still w^hile the celestial sphere spun 

 around it, covering in the earth much as a telescope dome covers in 

 the telescope ; and this dome was spangled with stars, which had 

 been thoughtfully added so as not to leave the central earth unillu- 

 mined at night. Ten generations at most have been able to view 

 the problem of their existence in anything like its proper astronom- 

 ical perspective. 



THE POSITION OF MAN IN THE UNIVERSE 



The total age of the earth far exceeds the 300,000 years or so of 

 man's existence. The evidence of geology, and of radioactivity in 

 rocks in particular, shows that it must be something like 2,000 million 

 years, wdiich is several thousand times the age of the human race. 

 Old INIother Earth must regard man as a very recent apparition 

 indeed; he has just appeared to burrow into her, burn her forests, 

 put her waterfalls into pipes, and generally mar the beauty of her 

 features. If he has done so much in the first few moments of his 

 existence, she may well wonder what is in store for her in the long 

 future ages in which he is destined to labor on her surface. 



^ The Trueman Wood lecture delivered before the Royal Society of Arts on Wednesday, 

 Mar. 7, 1928. Reprinted by permis.sion from Supplement to Nature, No. 3047, Mar. 



24, 1928. 



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