Scientists struggled to come up with an answer but to no avail. Enter a young pattent officer in Switzerland named of course, Sergey Nickolay ch. Just kidding, it was Albert Einstein. He proposed a very simple answer to this problem. There is no ether.
Light travels at a constant velocity regardless of the motion of the object that is measuring it.
Einstien simply said that it just is. We live in a universe in which the speed of light is constant. Now this seems very simple but there were consequences of this. Einstein of course, had help. What happed though was the concepts of absolute space and absolute time went out the window.