Michelson-Morley experiment

Aim of the Michelson-Morley experiment: The Michelson-Morley experiment was done to confirm the presence of hypothetical medium called ether.

Therefore, one question should be there what was ether? Yes, I have used “was ether” not “is ether”. Let us discuss why?

As we have already discussed in earlier articles that there is nothing like absolute rest. Thus the scientists in the 19th century assumed that our universe is filled with hypothetical medium called ether. Ether was supposed to be transparent and highly elastic.

The main objective of this Michelson-Morley experiment was to check the presence of this medium called ether. The aim was supposed to be fulfilled by measuring the velocity of the earth with respect to the ether. If earth is supposed to be propagating through the stationary ether with a uniform velocity and if a beam of light is sent from source to observer towards the direction of the motion of the earth, then it should take more time if sent through the opposite direction. If this time difference can be measured then velocity of earth with respect to ether can be measured.

Experimental arrangement of Michelson-Morley experiment: Continue reading “Michelson-Morley experiment”

Einstein postulates of theory of relativity

Explanation of the negative results of the Michelson-Morley experiment:

As the theoretical results of the M-M experiment did not match with the experimental results (Theoretically fringe shift result was not zero, it was about 0.4 but the experimentally it was 0). Even then the scientists of that time had conviction that ether exist and earth moves with respect to it. Thus there was lot of debate and discussion regarding this as why there were negative results (that is why the theory and experiment result did not match?).

Following are the reasons given by the scientists:

1.  Ether Drag Hypothesis: The then scientists assumed that ether exits and it is attached with the earth. Thus it will be dragged with the earth so the relative velocity of ether and earth will be zero. If this is taken then theory and experimental will get matched. But this hypothesis is discarded as there was no proof for this.

2. Lorentz-Fitzgerald Hypothesis: Lorentz told that the length of the arm (distance between the pale and the mirror M2) towards the transmitted side should be L(√1 – v2/c2) but not L. If this is taken then theory and experimental will get matched. But this hypothesis is discarded as there was no proof for this.

Einstein explanation of negative results of M-M experiment: Continue reading “Einstein postulates of theory of relativity”