Newton's theory of gravity posited instantaneous gravitational attraction, successfully predicting planetary orbits. Einstein's special relativity challenged this, necessitating the development of ...

Legend has it that Isaac Newton had the moment of inspiration that would lead to his theory of gravity when, on a warm afternoon, he saw an apple fall from a tree and wondered why it should fall down ...

Barry Lienert, a geophysicist at the University of Hawaii, provides the following explanation. We start by determining the mass of the Earth. Issac Newton's Law of Universal Gravitation tells us that ...

We now have the most precise estimates for the strength of gravity yet. Two experiments measuring the tiny gravitational attraction between objects in a lab have measured Newton’s gravitational ...