Hendrik Lorentz was a 19th-century Dutch physicist who invented local time and whose transformations Einstein used.
Quotes by Hendrik Lorentz in Time One
Indeed, one of the most important of our fundamental assumptions must be that the ether not only occupies all space between molecules, atoms or electrons, but that it pervades all these particles. We shall add the hypothesis that, though the particles may move, the ether always remains at rest. We can reconcile ourselves with this, at first sight, somewhat startling idea, by thinking of the particles of matter as of some local modifications in the state of the ether. These modifications may of course very well travel onward while the volume-elements of the medium in which they exist remain at rest.
[T]he daring assertion that one can never observe velocities larger than the velocity of light contains a hypothetical restriction of what is accessible to us, one which cannot be accepted without some reservation.
According to Einstein it has no meaning to speak of motion relative to the aether. He likewise denies the existence of absolute simultaneity. It is certainly remarkable that these relativity concepts … have found such a rapid acceptance.
[I find] a certain satisfaction in the older interpretations, according to which the ether possesses at least some substantiality, space and time can be sharply separated, and simultaneity is not relative.