WHAT WE DO WITH OUR BRAINS 3 



we were commenting on some of the stupendous 

 numbers employed by the astronomers in measuring 

 the distances of the stars. The unit of measure here 

 is the light-year, that is, the distance traversed by 

 light in a year — about six million million miles, or 

 6X10". The nearest fixed star whose distance has 

 been measured, alpha Centauri, is about four light- 

 years from the earth, and it has recently been esti- 

 mated that the giant nebula Andromeda is about a 

 million light-years away. Expressed in miles, the 

 distance to the star alpha Centauri is about 24X10" 

 and to Andromeda about 6X10^^. 



Turning now to smaller things, the diameters of 

 the atoms have been computed. My mathematical 

 friend tells me that in a cubic centimeter of water the 

 number of atoms is lo^-^. Extending the computation, 

 the solar system contains lo^^ atoms and the entire 

 visible sidereal universe contains about 10^^. atoms. 



Such numbers stun the imagination of the non- 

 mathematical mind. But a little computation shows 

 that the known complexity of the nervous connections 

 of the human body present possibilities of associa- 

 tional combinations of the nerve cells among them- 

 selves that run into numbers of even greater orders 

 of magnitude. 



The total number of cells in the human body has 

 been estimated by Francke to be about 2.65X10^^, 

 a number which is probably too small. Of this total, 

 the larger proportion (2.25 X 10'^) are blood corpuscles 



