Actually, Einstein was not influenced
so much by the Michelson-Morley experiment at the
time when he wrote down The Postulates of Special
Relativity as he was by his so-called "Gedankenexperimenten" (imaginary "experiments" in
his head) and by Ernst Mach and his principle, Mach's
principle1, as well as by Poincaré and
his book La Science et l'Hypothèse.
1Mach's principle: The
inertial forces experienced by a body in nonuniform
motion are determined by the quantity and distribution
of matter in the Universe.