While it is widely accepted that there is no existence of the aether, what does this say about Dirac's argument which contradicts mainstream belief? This comes about 50 years after it was suggested that there was no aether. Is this a special case? I was told that aether theory is not excluded by experiments or theoretical reasons, it is just relatively ugly. So to say that the Michelson-Morley experiment disproves the luminous aether too strong of a statement?