Interactive Experiments in Gravity
This directory contains documents and interactive
Java applets 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.
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.
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
applet that lets you explore such orbits and explains the theory
by John Walker