In 1676 Roemer, while studying the satellites of Jupiter for an unrelated matter, was the first to find an indication that the speed of light was actually finite. As astonishingly great as that speed turned out to be (about 300,000 km/s), the real surprise came 2 centuries later.
By 1879, Michelson had determined the speed of light to an accuracy of +/- 50 km/s and for the first time the error was smaller than the back and forth speed of the Earth around the Sun (2x30 km/s), the next fastest accessible speed.
In one of physics' most celebrated experiments Michelson and Morley concluded in 1887 that the speed of light appeared unchanged by the movement of its source or that of the observer. This was unlike any speed from any other source and could not be explained by the laws of physics as they were then known.
In 1905 Einstein proposed the theory of Special Relativity to deal with this puzzle, and our understanding of the laws of Nature has become much more sophisticated. There is a special kind of relation between time and space, Einstein told us, and hence a special speed, and it appears that light has that speed. At, or near, that speed, things don't behave quite like what we are used to.
We propose to relive the key experiments of this fascinating history over the course of 2002 by recreating, hands on, some of these experiments. We will measure the speed of light and focus on using today's technology that is easily accessible to amateurs while keeping costs as low as possible.
With the notable exception of Empedocles, most classical thinkers either assumed or reasoned that the speed of light was infinite. The first recorded attempt to measure c was that of Galileo's in 1626 but he could not rule out that the speed was indeed infinite.
source: K. D. Froome and L. Essen, "The Velocity of Light and Radio Waves", Academic Press, 1969
The table shows the merging of 3 different research lines (light, electric and magnetic units, radio waves). Indeed, over this period radio waves first emerged from the laws of electricity and magnetism and then the radio wave nature of light was established.
If you are, or will be, conducting experiments for this project, consider documenting your efforts for inclusion here. Send your pages, enquiries etc..., to email@example.com.
Backyard Roemer:Vincent Goffin is documenting an attempt to redo Roemer with a 3.5" telescope.
Modern Roemer:Geoff Hitchcox, from New Zealand, has modified Roemer's methodology to use modern orbital information.
More Experimentswere carried out by NJSAS members and were presented at the Phila. convention. We hope to have them documented here soon.
Your Experiment:by You! The contest year may be drawing to a close, but there will always be room on this site for more amateur contributions.
Michael Fowler's lectures from virginia.edu