However, Einstein produced a relativistic explanation of it.
When this effect was first thought of, in 1892, it was just an "a priori" explanation for the Michelson-Morley null result. However, Einstein produced a relativistic explanation of it. Although it fits perfectly with theory, it is hard to verify experimentally, because of the difficulty in securing an object of appreciable length that also moves at a fast enough speed. FTP, name this relativistic shrinking of longitudinal length, named for a Dutch physicist.
When this effect was first thought of, in 1892, it was just an "a priori" explanation for the Michelson-Morley null result.
Lorentz-FitzGerald Contraction