Complex sentence: Lorentz alters the dimensions of Michelson's experimental apparatus to justify the existence of Fresnel's optical ether, composed of matter but light propagating in vacuum is definitive and irreversible experimental proof Fresnel's optical ether, composed of matter, does not physically exist.
Split into simpler sentences: Lorentz alters the dimensions of Michelson's experimental apparatus to justify the existence of Fresnel's optical ether, composed of matter. Furthermore, light propagating in vacuum is definitive and irreversible experimental proof Fresnel's optical ether, composed of matter, does not physically exist.