The theory of relativity he described as “a mass of error and deceptive ideas violently opposed to the teachings of great men of science of the past and even to common sense.
New York Times article on Nikola Tesla
Sources
New York Times
Tesla, 79, Promises to Transmit Force
Other
July 11th 1935 - Assails Theory of Relativity. as Work of Metaphysicians and Not Scientific.