Short answers, pulled from the story.
Gravity is the word used to describe a physical law and a fundamental physical interaction that derives primarily from mass. It is the invisible hand that draws material objects towards each other, operating with an infinite range even though its effects become weaker as objects get farther away.
The Indian mathematician and astronomer Brahmagupta proposed the idea that gravity is an attractive force that draws objects to the Earth in 628 CE. He used the term gurutvākarshana to describe this force.
Isaac Newton published his groundbreaking book called Philosophiæ Naturalis Principia Mathematica a few years after sending a manuscript to Edmond Halley in 1684. The book provided a physical justification for Kepler's laws of planetary motion and established the inverse-square law.
Albert Einstein developed a theory of general relativity in 1915 which was able to accurately model Mercury's orbit. This theory brought the principle of relativity and non-Euclidean geometry into the physical theories of gravity.
The first direct evidence for gravitational radiation was measured on the 14th of September 2015 by the LIGO detectors. The gravitational waves emitted during the collision of two black holes 1.3 billion light years from Earth were measured.
The phenomenon of gravitational lensing was first confirmed by observation in 1979 using the 2.1 meter telescope at Kitt Peak National Observatory in Arizona. The telescope saw two mirror images of the same quasar whose light had been bent around the galaxy YGKOW G1.