Michelson-Morley Apparatus

In 1887 Albert Michelson and Edward Morley measured the speed of the earth with respect to the ether, a substance postulated to be necessary for transmitting light. Their method involved splitting a beam of light so that half went straight ahead and half went sideways. If the apparatus (attached to the earth) moved relative to the ether, then light going in one direction should travel at a different speed than light going in the other, just as boats going downstream travel faster than boats going across. No evidence of a difference in speed was found, however, which led not only to the demise of the ether theory, but to the development of the Special Theory of Relativity by Albert Einstein 18 years later.

 

Dragging Space and Time

The results of two studies announced in early November 1997 provide unprecedented support for “frame-dragging,” a concept predicted by physicist Albert Einstein's general theory of relativity. Frame-dragging describes how massive objects actually distort space and time around themselves as they rotate. One of the studies examined frame-dragging around black holes, an example of which is shown here in an artist's conception.