Lee Smolin: "Where are the Einsteinians? Special relativity was the result of 10 years of intellectual struggle, yet Einstein had convinced himself it was wrong within two years of publishing it." http://www.logosjournal.com/issue_4.3/smolin.htm
Within two years? What happened in 1907? Voilà:
John Norton: "Already in 1907, a mere two years after the completion of the special theory, he [Einstein] had concluded that the speed of light is variable in the presence of a gravitational field." http://www.pitt.edu/~jdnorton/papers/OntologyOUP_TimesNR.pdf
Does "variable in the presence of a gravitational field" entail "variable in gravitation-free space"? Of course. The equivalence principle implies just that.
Einsteinians are in panic nowadays, silently leave Einstein's sinking ship and promptly become experts in quantum mechanics, AI, climate science, COVID-19, anything. The ship is almost empty. Only Kip Thorne is still there - his money is too heavy:
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