Michelson and Morley mounted their apparatus on a stone block
floating in a pool of mercury, and rotated it to seek changes in relation
to the motion of the earth in its orbit around the sun. They arranged
one set of light beams to travel parallel to the direction of the
earth's motion through space, another set to travel crosswise to the
motion.
No difference could be found. Other experiments on the speed
of light also produced results contrary to what physicists expected.
These experiments, like most important new science, were done
at the very limit of available techniques. The results were long
in dispute. It was only after the invention of lasers that it became
easy to show beyond reasonable doubt that the speed of light is
invariable.
You can EXIT
to a full explanation from Georgia State University, or
EXIT
to read the Michelson-Morley paper
|