Re: [Phys-l] status of Occam's razor

[Richard Grandy <rgrandy@rice.edu>]

> On 08/02/2007 11:09 AM, chuck britton wrote:
> >  An Historical Question concerning Occam's Razor -
> > 	Devil's Advocate Hat On:
> >
> >  When did the Copernican Theory of our Solar system become as precise
> >  as the Ptolmeic Theory?
> >  Did Newton work out the perturbations required - or am I totally
> >  bonkers in believing someone who claimed that all the cycles and epi-
> >  cycles DID give more precise predictions than did Copernicus (and
>  > Kepler)?


You have to distinguish the simplified Copernican system with only 
seven circles, from the full Copernican system with 30.  The former 
is less accurate than the  simplified Ptolemaic.  The full systems 
are equally accurate (Kuhn, The Copernican Revolution, 169)

The Copernican system gives an explanation of the retrograde motion 
of the planets that the Ptolemaic simpllyi describes.  But one major 
turning point was that the Copernican system leads to the prediction 
that Venus will have phases, and those were observed when the 
telescope was invented.

Richard Grandy
Rice University
Houston TX USA

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