Negative result of Michelson's experiment (1887) excited theoreticians. Just in 1892 Irish physicist G.F. Fitzgerald noted that this result may be explained assuming that dimensions in the direction of the movement become shorter by a √(1-v2/c2) factor.
This idea in itself is not so atrificial: H.A. Lorentz (and also M. Abraham), working among others on propagation of electromagnetic waves in material media, explained (1895) this phenomenon as interaction electrons of the matter with the ether.
But, that idea was not acceptable at all for French mathematician H. Poincaré, which in 1904 during the conference in Saint Luis said: "Rules of the Physics should be the same both for non moving observer and constantly moving observer; in that way we don't have and will not have any way to say if we are moving in such a way".
In this way the theory of relativity was formulated for the
first time.*
*It is well known, that A. Einsten got
the Nobel Prize not for the theory of relativity,
but for the explanation of the photovoltaic effect.
I was because of the negative opinion on that theory by one of the members
of the Nobel Committee. Re-reading original works one notes that the "photovoltaic"
article was absolutely Einsten's only, and to theory of relativity there
could be many pretenders [GK].