Scientific Revolutions

Now, what is the relationship among these three pictures? It is clear that the Copernican-Galilean-Keplerian-Newtonian revolution overthrew the Ptolemaic system, in the sense that Ptolemy is only taught as history and never as science. But I predict that Newton will always be taught, because Newton’s picture is basically right - on the scale of the solar system. The scientific revolution that led to the modern cosmos, including the early 20^th century contributions of Relativity and Quantum Mechanics, have encompassed Newtonian physics with physics that works at astronomical scales and velocities. But Modern cosmology reduces to the Newtonian treatment for the solar system, for normal sized things on Earth, and generally for conditions where speeds are not too high and gravitational forces are not too great. So, we can really only say we know that a theory is right when we know where it is wrong. Inside the boundary where the theory begins to fail, the theory is correct (to some prearranged accuracy). Modern cosmology is undergoing an encompassing revolution as opposed to an overthrowing revolution.

Table 1. Three Cosmologies: Medieval, Newtonian, and Modern.

Contributed by: Joel Primack and Nancy Abrams