FOM: Re: Copernicus

[Gordon Fisher]

José Félix Costa wrote:

> Alexander R. Pruss and Palma wrote inter alia,
>
> ''general relativity had also been formulated by or available to Copernicus,
> then he could have realized that saying the sun goes around the earth and
> the earth goes around the sun are equivalent in the sense that one can
> choose coordinates so that each of these is tenable''

Actually, I wrote this (Gordon Fisher), referring to statements
by Einstein and Infeld in their book _The Evolution of Physics_.
Here is the exact quotation, taken from my book _The Marriage
and Divorce of Astrology and Astronomy_ which may be found at
http://www.gfisher.org  (paragraph 2 of Chapter 7)

         2.  Is it false that the sun goes around the earth?  Albert Einstein
and Leopold Infeld say in their The Evolution of Physics 1938, p 212):  "Can we
formulate physical laws so that they are valid for all CS [coordinate systems],
not only those moving uniformly, but also those moving quite arbitrarily,
relative to each other?  If this can be done, our troubles will be over.  We
shall then be able to apply the laws of nature to any CS.  The struggle, so
violent in the early days of science, between the views of Ptolemy and
Copernicus would then be quite meaningless.  Either CS could be used with equal
justification.  The two sentences, "the sun is at rest and the earth moves," or
"the sun moves and the earth is at rest," would simply mean two different
conventions concerning two different CS.  Could we build a real relativistic
physics valid in all CS; a physics in which there would be no place for
absolute, but only for relative motion?  This is indeed possible! [general
relativity]."

>
>
> This argument goes back to Nicolaus Oresmus and Cusanus (Nicolas of Cusa).

> However, the argument is valid only until the discovery of paralax.
>

Not sure about this.  I once studied the work of Nicholas of
Cusa, but this was a long time ago.  My initial reaction is that
what Nicholas and some others were talking about were
uniform motions, i.e. circular motions with constant angular
speed, and moreover what came to be called absolute
motions, considered with respect to some fixed entity, be
it the earth or the sun.  Moreover, the notions up to
the time of Kepler (with his anima motrix) and Newton
(with his force of gravity) were, as I recall, chiefly
kinematic rather than dynamic, as far as our solar system
is concerned.  This is not to say that there weren't
some ideas of "force" before Newton -- for example,
Aristotle had certain ideas along these lines, although
he notoriously got the wrong mathematical idea about
falling bodies near the surface of the earth.

>
> ''It's also interesting to note that the mere claim that the Copernican
> hypothesis is simpler for calculation would have been acceptable to everyone
> involved.''

I did not write this, however -- Gordon Fisher.

>
>
> This is not true! The Copernican hypothesis is not simpler (is worse than
> Ptolomaeus')! The orbits should stay circular (accordingly to Neoplatonic
> and Aristotelic philosophy). Using circles the movement of a heavenly body
> could be expanded in Fourier Series in two dimensions having the Sun at the
> center or the earth. Each circle is an epicicle. Copernicus' theory has more
> epicicles than Ptolomeus'. Fred Hoyle did this calculation several years
> ago. The number of circles in the Revolutionibus is over 50.
>

Yes.  I quote again from my book (paragraph 76 of Chapter 4),
from a work by Neugebauer and Smerdlow ((N. M. Smerdlow and
Otto Neugebauer, Mathematical Astronomy in Copernicus's
De Revolutionibus, 1984).

        76.  It has often been said that the Copernican heliocentric theory was
superior to the Ptolemaic theory because it was simpler.  However, Smerdlow and
Neugebauer observe:  "Anyone who thinks that Copernican theory is "simpler" than
Ptolemaic theory has never looked at Book III of De revolutionibus.  In a
geocentric system the earth is at rest -- as indeed it appears to be -- and any
apparent motions in the heavens that we know to result from its motions are
distributed among a number of objects, i.e. the sun, the individual planets, the
sphere of the fixed stars, everything in its proper place as it actually
appears.  But when Copernicus worked through the consequences of his own theory,
he had to attribute to the earth no less than three fundamental motions and a
number of secondary motions.  That all these compounded motions forced upon a
single and, to all appearances, quiescent body seemed implausible to his
contemporaries is not to be wondered at, especially because the end result was
nothing other than reproducing the same apparent motions in the heavens that had
been accounted for all along (and without making assumptions that contradicted
contemporary natural philosophy, common sense, and the most casual or most
meticulous observations then possible of the behavior of the earth and of
objects on or near its surface)."  (Smerdlow and Neugebauer, ibid., p. 127.)



>
> Essais where all these calculations are made are Westerman, Hoyle and mainly
> the great Naugebaur.
>

The spelling is Neugebauer



>
> Finaly he argument of Copernicus is not simplicity. It is metaphysical.
>
> See in the Revolutionibus, introduction, and in Kuhn.
>

Yes, Copernicus had some metaphysical, or perhaps one
can say mystical, ideas about the role of the sun in our
solar system.  That is, they are metaphysical or mystical
in the context of more recent physical cosmology.

>
> Cheers,
>
> Felix
>
> +++++++++++++++++++++++++++++++++++++++++++++++
> J. Felix Costa
> Departamento de Matematica
> Instituto Superior Tecnico
> Av. Rovisco Pais, 1049-001 Lisboa, PORTUGAL
> tel:      351 - 21 - 841 71 45
> fax:     351 - 21 - 841 75 98
> e-mail:   fgc at math.ist.utl.pt
> www:    http://www.cs.math.ist.utl.pt/cs/fgc.html
> +++++++++++++++++++++++++++++++++++++++++++++++

Gordon Fisher     gfisher at shentel.net