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Sir Hoyle on Copernicus and Ptolemy



I came across with a Finnish book on philosophy. It cited Sir Fred Hoyle's book "Nicolaus Copernicus". I translate from Finnish to English because I don't have the original text:

"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."

Hoyle considered both Newtonian physics and Einstein's relativity theory before reaching this conclusion. I guess that by Ptolemy's theory he referred to the idea that it is the Sun (and other celestial objects) which revolves around the Earth.

I understand that a reference frame can be attached to the Earth as well as to the Sun. But this does *not* imply, I believe, that there is no way of telling if the Earth revolves around the Sun or vice versa. As far as I know, the Earth (and the Sun) revolves around the center of mass (CM) of the Earth-Sun system. This CM lies near the center of the Sun.

What could then be Hoyle's point? He was after all, an eminent astrophysicist. Has anybody read Hoyle's book on Copernicus?

Regards,

Antti Savinainen
Kuopion Lyseo High School/IB
Finland
Homepage: <kotisivu.mtv3.fi/physics/>