
Some ideas, such as Leonardo da Vinci's helicopter, are ahead of their time in that it would not be possible for da Vinci to construct a functional model. But what ideas are behind their time? This is to ask: which technologies could have arrived earlier because their prerequisites were already present?
Brian Potter, an engineer, asserts that the Wright brothers' flyer could have been constructed the late 1880s instead of 1903. The constituent technologies for the turbojet, which first appeared in 1937, were known in the 1920s.
Much depends on how one defines "plausible" and the risks that inventors are willing to take. Japanese physician Hanaoka Seishū (1760-1935) was the first surgeon in the world to use general anesthesia in 1804, but blinded his wife and crippled his mother while trying to get the dosage right.
-via Marginal Revolution










