Interactive Experiments in Gravity

This directory contains documents and interactive resources which explore aspects of both Newton's theory of universal gravitation and Einstein's general relativity.

The first two installments in the series are now available.

Bending Spacetime in the Basement

Torsion balance moving under the force of gravity

We live our entire lives within the Earth's gravitational field, yet rarely if ever do we experience the universality of gravitation: that every object in the universe attracts and is attracted by every other. This page presents a “basement science” experiment which reveals the gravitational attraction between objects less than a kilogram in mass. Knowledge in antiquity suggesting gravitation was universal is discussed, and the feasibility of an experimental test using only materials and techniques of the era is explored.

Orbits in Strongly Curved Spacetime

Orbits in Strongly Curved Spacetime sample screen

Close-in orbits around compact massive objects such as neutron stars and black holes trace out paths drastically different from the ellipses of Kepler's Laws. Since the velocity of an orbiting object cannot attain or exceed the speed of light, Einstein's general relativity predicts a different energy curve, resulting in precession absent in Newton's theory. This page includes an interactive animation that lets you explore such orbits and explains the theory behind them.

by John Walker