For those unaware - the most famous experiment to measure this(both high school and university physics classes have drilled this into my brain): https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_exper... a long history of experiments failing to find evidence of an ether https://en.wikipedia.org/wiki/Tests_of_special_relativity

It's different when you invalidate your own research.