________________
50
TULASI-PRAJNA, June, 1990
possibility of any error. The result was that no change in the velocity of light beams traversing in any direction was recorded. In other words, the apparent velocity of the earth through ether was zero. The experiment was repeated several times, but no motion of the earth relative to the ether was detected.
As a result of this important experiment, two possible conclusions: were suggested :
1. There exists ether but the motion of the earth through it has no effect on it. This would mean that the earth stands still in ether.
2. There exists no such substance as ether.
If the first alternative was accepted, the scientists had to abandon the still more venerable copernican theory that the earth is in motion, which seemed nearly impossible for them. At the same time, if they accepted the second alternative abandoning the ether, they had no
anation for the wave theory of light. To many physicists it seemed almost easier to believe that the earth stood still than that waves light waves, electromagnetic waves-could exist without a medium to sustain them. It was a serious dilemma and one that split scientific thought for a quarter century. Many new hypothesis were advanced and rejected , Fitzgerald and Lorentz
Meanwhile, Fitzgerald (1893) and Lorentz (1895) independently put forward explanation to account for the negative results of the Michelson-Morley experiment. The experimenters had in fact tried to make two rays of light travel simultaneously to and fro over two courses of equal length. Without losing anything of the essence of the experiment, we may imagine that the lengths of the two courses had been measured or compared by ordinary measuring rods-footrules, if we like. How was it known, Fitzgerald and Lorentz asked, that these rods, or the course laid out by them, retained their exact length while they were moving forward through a sea of ether? They argued that if the measuring rod, when it moves, undergoes a contraction in length, it would not be possible for us to comprehend the effect of ether on the velocity of light. Thus, if the apparatus used by Michelson and Morley contracted in the same way, the up-and-down stream course would always be shorter than the cross-stream course. This reduction of length would do something to'compensate for the other disadvantages of the up-and-down stream coursé. A contraction of exactly the right amount would compensate for them completely, so that this and the cross-stream course would require precisely equal times. In this way, Fitzgerald and Lorentz suggested, it might be possible to account
Jain Education International
For Private & Personal Use Only
www.jainelibrary.org
