*[http://www.relativitycalculator.com/Kepler_1st_Law.shtml Johannes Kepler empiricism and mathematics provided the basis for Newton's laws of motion and gravity]
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*[http://www.relativitycalculator.com/Kepler_1st_Law.shtml Johannes Kepler empiricism and mathematics provided the basis for Newton's laws of motion and gravity]
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*[https://www.relativitycalculator.com/Kepler_2nd_Law.shtml Kepler's 2nd Law ( Equal Areas in Equal Times: Variable - speed model )]