Re: Sir Hoyle on Copernicus and Ptolemy

[John Clement <clement@HAL-PC.ORG>]

There certainly are effects that one can predict from the Copernican theory
that are not present in the Ptolomaic theory.  Both the Foucault pendulum
and the coreolis pseudoforce can be predicted by the Copernican theory.
Notice that part of the Copernican theory must be that the earth rotates.  I
think that Hoyle may have been given to stretching a point a bit.  After all
he was an excellent author of both scientific papers and fiction.  In
classical mechanics the rotating earth is not exactly equivalent to the
fixed earth as the rotating earth is an accelerated reference frame, while
the fixed earth is an inertial frame.  In accelerated frames pseudoforces
are present which will not appear in the inertial frame.

The original Copernican theory unfortunately still had much of the Ptolemaic
machinery intact such as the epicycles, and those had been tuned to get very
good agreement with the existing data.  Kepler's model relied on the more
accurate new data taken by Tycho Brahe.  In a sense each of these theories
owes a debt to the previous one.  In addition each of these theories
requires development of a new paradigm which may not be acceptable to others
at that time.

I think that the statement you are asking about might make more sense if I
knew the broader context in which it was made.  It is obviously part of an
argument, and in context it might make much more sense.  Perhaps he is
thinking about relativistic mechanics???

John M. Clement
Houston, TX

> Hello again,
>
> perhaps I did not ask clearly enough. Sir Hoyle stated that (my
> additions in
> brackets):
>
> "Today [1973] we cannot claim in any physically meaningful sense that
> Copernican theory
> [i.e. the Earth revolves around the Sun; not other way round]
> would be right
> and Ptolemy's theory would be wrong.
> These two theories have no difference whatsoever from the point of view of
> physics."
>
> Copernicus proposed that the Earth is not "fixed", it revolves
> around the Sun.
> Is this correct or not?
> Or is it *just* a matter of reference frame?
>
> - - - - - -
>
> BTW there is a good scientific reason why the original Ptolemy's model was
> replaced by Kepler's model. Kepler's
> theory provided better predictions than Ptolemy's model.
> Interestingly enough,
> Copernicus' model
> was no better than Ptolemy's model in terms of predictions.
>
> Regards,
>
> Antti
>
> Antti Savinainen
> Senior Lecturer in Physics and Mathematics
> Kuopion Lyseo High School
> Puijonkatu 18
> 70110 Kuopio, FINLAND
> E-mail: antti.savinainen@kuopio.fi
> Personal web page: http://kotisivu.mtv3.fi/oma/physics/