@BillRM,
The starting assumption for relativity is that the Michelson/Morley experiment did indeed fail. Nonetheless, when people have run the experiment with more advanced instruments, it has not failed.....
Michelson/Morley reruns:
http://www.orgonelab.org/miller.htm
https://www.youtube.com/watch?v=g_loyzL9Wi4
http://www.anti-relativity.com/forum/viewtopic.php?t=2545
In a 1986 letter to Nature[42] Ernest W. Silvertooth reported that he constructed an interferometer capable of detecting the absolute motion of the Earth with respect to the ether. In Experimental detection of the ether[43] and Motion through the Ether[44], Silvertooth reported that on the particular day of his measurements, the Earth moved at 378 km/s towards the constellation Leo. If relativity is correct, than this result should be complete garbage.
Silvertooth published his findings before NASA launched COBE, the first satellite to accurately measure the cosmic microwave background (CMB). Due to Doppler shift, there is a slight anisotropy in the spectrum of the CMB. Based on precise measurements of this anisotropy,
it was determined that, relative to the CMB, the heliocentric frame moves at 390 km/s towards Leo. Given the earth's orbital speed of 30 km/s, this is a very good agreement with Silvertooth's measurement. In a refined experiment[45], Silvertooth and Whitney confirmed the earlier result and found a speed of v = 378 km/s.
A citation search through ISI Web of Science[47] reveals no references to any of Silvertooth's papers in the mainstream scientific literature. An online document[46] briefly mentions and dismisses it on the grounds that both the experiment and the theoretical analysis are flawed,
but given how well Silvertooth's result agrees with the independently determined motion of the Earth through the CMB, error seems to be an insufficient explanation. Unless Silvertooth committed outright fraud by simply making a lucky guess as to the Earth's velocity relative to the CMB and then ascribing this guess to an imaginary experiment, the inescapable conclusion would be that translation can be measured by purely electromagnetic means and that Einstein's theory of special relativity is falsified.