Short answers, pulled from the story.
Leucippus proposed that a large group of atoms swirled as a vortex to create the cosmos. Smaller atoms became celestial bodies while larger ones formed Earth at the center.
Galileo hypothesized in a letter dated the 1st of January 1604 that distance is proportional to the square of time elapsed. Grimaldi and Riccioli confirmed this relation between the 1st of January 1640 and the 31st of December 1650 using pendulum oscillations.
Philosophiæ Naturalis Principia Mathematica appeared in the year 1687 with Halley's support. Robert Hooke wrote to Isaac Newton about orbital motion on the 1st of November 1679, and Halley visited Newton in January 1684 asking what trajectory an inverse square force would produce.
Albert Einstein described free fall experiencing no gravitational field as the happiest thought of his life in 1907. He published papers establishing special relativity in 1905 claiming mass and energy are equivalent.
LIGO experiments directly detected gravitational waves from two colliding black holes in the year 2015. Neutron star mergers since detected in 2017 may also create detectable amounts of gravitational radiation.