Re: The Cosmological Principle

Sam Wormley wrote: 
oriel36 wrote:

To Sam

The first people to enjoy the original heliocentric thinking based on
how  apparent retrograde motions were resolved will have no time for
Newton and is muddle headed ideas on planetary motion.


Johannes Kepler -- more than 900 pages of calculation in about four
years attempted to measure the orbit of Mars

  o from a moving platform
  o who's orbit was not centered on the Sun
  o rotating on its axis
  o of a planet varying in its orbital speed around the Sun.

Kepler's calculations were immensely difficult... but he eventually realized
that an ellipse with an eccentricity of about nine percent agreed with
Tycho Brahe's observational data. Kepler found that the orbits of planets
in our solar system follow ellipses, sweeping out equal areas in equal
times (Newton would later show this as the conservation of angular
momentum as you point out).

Newton discovered (and showed mathematically) that objects in free fall
(such as planets influenced by a central force like the Sun's gravity)
follow the paths of conic sections.

Ref: http://learning.physics.iastate.edu/DemoRoom/MU.htm#22 

  Available for viewing online
    http://www.learner.org/resources/series42.html


The combination of Newton's law of gravity and F=ma . The task of
deducing all three of Kepler's laws from Newton's universal law of
gravitation is known as the Kepler problem.  Its solution is one of the
crowning achievements of Western thought.

A model for Gravitation was essential.
  http://scienceworld.wolfram.com/physics/Gravity.html

.

Relevant Pages

  • Re: The Cosmological Principle
    ... Newton and is muddle headed ideas on planetary motion. ... Kepler found that the orbits of planets ... A model for Gravitation was essential. ...
    (sci.astro.amateur)
  • Re: Vaccum in Space
    ... Newton's laws of motion and Newtons law of gravitation. ... Isaac Newton, showed mathematically, that objects in free fall ... Kepler found that the orbits of planets ...
    (sci.astro.amateur)
  • Re: Vaccum in Space
    ... Newton's laws of motion and Newtons law of gravitation. ... Isaac Newton, showed mathematically, that objects in free fall ... Kepler found that the orbits of planets ...
    (sci.astro.amateur)
  • Re: Q question about relativity
    ... is seeing that even light is bent according to gravitation. ... the mass of the photon is zero, so the light beam cannot be ... > bent according to Newton, ...
    (sci.physics)
  • Re: Q question about relativity
    ... is seeing that even light is bent according to gravitation. ... the mass of the photon is zero, so the light beam cannot be ... > bent according to Newton, ...
    (sci.physics.relativity)