FOM: Copernicus and Newton
marksa at vms.huji.ac.il
Thu Feb 28 02:04:02 EST 2002
The underlying, yet not entirely explicit, ideas behind Newton's destruction
of the geocentric sentence, is that (a) all forces are exerted by bodies, and
empty absolute space (though it does exist for Newton) cannot exert forces and
(b) no force can increase with the distance from the body that exerts it. Now,
for all heavenly bodies to go around the earth in 24 hours, this means that the
earth itself would have to exert a force which increases with the distance
José Félix Costa wrote:
> 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 math.ist.utl.pt
> www: http://www.cs.math.ist.utl.pt/cs/fgc.html
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