THE EVOLUTION OF SCIENTIFIC THEORIES 285 



■examples the earliest and the two most recent of the scientific devel- 

 opments commonly so denominated. 



Speaking as a cosmologist I cannot fail to recognize a Copernican 

 Revolution: an older world view is completely shattered. But where 

 is the revolution in science? Astronomers are newly reminded not to 

 accept uncritically all that seems obvious to common sense. But for 

 some 2000 years already astronomers had been busy seeking im- 

 mutable regularity in celestial motions quite "obviously" irregular. 

 Astronomers are newly counseled also to deploy fully the powers of 

 mathematics, but that counsel had been audible, long before Eu- 

 doxus, even to the Babylonians. And, as for centuries before, so too 

 after the Copernican "Revolution" astronomers continue to observe 

 "objects" in the sky while continuing also their endeavor to fit "or- 

 bits" to those observations. They now essay some new kinds of 

 orbits, with a new reference center; they look for some new things, 

 and make somewhat novel interpretations of what they see. But in 

 the practice of astronomy, what is the change aptly qualified as 

 ^'revolutionary"? 



An almost uninterrupted series of conspicuous successes had led 

 the typical physicist of the late 19th century to regard classical 

 physics as a completely secure foundation for the ultimate cos- 

 mology. The initial impact of Einstein's special relativity theory then 

 seemed devastating. But, when the smoke cleared, Planck at least 

 could detect no revolution in science: 



The theory of relativity . . . has proved to be the completion and 

 culmination of the structure of classical physics. 



Such "completion" seems peculiarly ill-suited to description as a rev- 

 olution. Did Planck perhaps suffer from astigmatism? With a philo- 

 sophic outlook very nearly the polar antithesis of Planck's, Bohr still 

 saw this development in much the same way: 



. . . the theory of relativity approaches, in a particularly high de- 

 gree, the classical ideal of unity and causality in the description of 

 nature. 



Einstein himself writes : 



With respect to the theory of relativity it is not at all a question of a 

 revolutionary act, but of a natural development of a line which can 

 be pursued [backward] through centuries. 



