Most popular science accounts and even text-books on the Special theory of Relativity start by describing the Michelson-Morley experiment,which leaves the impression that it played a decisive role in the development of relativity by Einstein.Some books like Kleppner/Kolenkow mention that it probably was of no great significance but fail to mention exactly what experiments,if any led Einstein to relativity.

One book does that.

"An Introduction to Special Relativity" by Robert Resnick describes two experiments that Einstein himself says played a part in the development of relativity-- stellar aberration and Fizeau's observation of the dragging of light by moving water(first predicted by Fresnel).

What is striking about these two experiments is that none of them,in a very clear-cut way,lead to the idea that the ether was a figment of the physicists' imagination.At least,they're not as unambiguous in their conclusions as the Michelson-Morley experiment.Einstein said in an interview,in his later life,that he wasn't quite sure if he knew much about Michelson-Morley when he discovered relativity.He says that at most,he might have been aware of the negative result,but not the actual details.This seems to be the correct version,as he admits having read a book by Lorentz,which mentioned it.

The real origin of relativity,then,mostly lies in a thought experiment Einstein had when he was 16--about what he would see if he ran alongside light at its speed.From the fact that Maxwell's equations of electromagnetism do not allow for a stationary electromagnetic wave,he deduced that there was something wrong with Newtonian conceptions and not with Maxwell's theory.None of the other greats of this era,Lorentz or Poincare saw the matter with as much penetrating clarity as this totally unknown worker at the Patent office in Berne.Einstein looked to the experiments for verification of his intuition and not as their origin.

The conclusion is astonishing in its implications.This means that Einstein was guided more by his own thoughts and intuition than by experiment.The crisis physics found itself in,led,not to more complications,but to a simplification of its foundations.This, I've realized gives the true measure of the man's achievement.Surely,this is what Erwin Schrodinger had in mind,when he said," The task is, not so much to see what no one has yet seen; but to think what nobody has yet thought, about that which everybody sees."

To my utter amazement,I found that the phenomenon of dependence of time intervals on relative velocity,could be derived by using nothing more than a theorem which every school kid is familiar with--the Pythagorus' theorem.

I had known this even before,but somehow,it had never quite sunk in.Einstein struggled with these ideas,on and off,for ten long years,before he finally found the answer.Further,he did all of this,on his own,with essentially no contact with any other physicist.

I'm only just beginning to realize what others have known all along.This man was a genius.