FOM: Copernicus and Newton

José Félix Costa fgc at
Tue Feb 26 12:34:23 EST 2002

Gordon Fisher wrote:

''I recall, chiefly kinematic rather than dynamic, as far as our solar
system is concerned.''

There is a small essay by Bernard Show on this. I will try to reproduce it
However I think that something else should be told.
Newton's first law is used TO FIND the right system of coordinates... The
stars, the stars far way... we define a tetrahedron from three fixed stars
and the Sun. Any particle as another distant star -- not subject to forces
because is far way from the others -- will move uniformly in straighline.
Now see one particle not moving uniformly in a line. Mesure the departure
from uniformity -- there you have the concept of force. Define it up to a
constant factor to be determined -- mass. Second law.
Now third law can be used to define mass from the ''colision'' experience.
In this sense it is dynamic and it concerns our solar system.

Remark: the concept of relativity in the solar system and the sources of
copernicanism is dealt with in an interesting way (Cusanus, Oresme and
Sacrobosco) in the book of Koestler ''The Sleepwalkers''.
I can report on this later.
However, I repeat myself, the mathematical sources of relativity are handled
in Hoyle's calculation.


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

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