MIRACLES OF SCIENCE 



problem as to the origin and destiny of the universe 

 which persistently thrusts itself upon the attention 

 of every speculative mind. 



WHY DO OLD STARS MOVE RAPIDLY? 



In Professor Campbell's own words "that stellar 

 velocities should be functions of spectral types (i.e., 

 should vary with the age of the star) is one of the 

 most surprising results of the recent studies in stellar 

 motions, for we naturally think of all matter as equally 

 old gravitationally. Why should not the materials 

 comprising a nebula [nacent star] or a class B [com- 

 paratively young] star have been acted on as long and 

 as effectively as the materials in the class M [very 

 old] star?" 



The rigidly scientific cast of Professor Campbell's 

 mind prevents him from attempting to give a decisive 

 and final answer to this question. But, on the other 

 hand, it !does not prevent him from suggesting a 

 scientific interpretation; only he is careful to avoid 

 all appearance of dogmatism even going to the 

 length of putting his explanations in the form of 

 question. 



Let me again quote his words : "The established' 

 fact of increasing stellar velocities with increasing 

 ages suggests the questions: Are stellar materials in 

 the ante-stellar state subject to Newton's law of 

 gravitation? Do these materials exist in forms so 

 finely divided that repulsion under radiation pressure 

 more or less closely balances gravitational attraction? 

 Does gravity become effective only after the proces- 

 ses of combination are well under way?" 



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