~1820 “Rail travel at high speeds is not possible because passengers, unable to breathe, would die of asphyxia.” - Dionysius Lardner
~1950 "Continental drift is impossible ... young scientists shouldn't work on such a stupid idea" - MIT geology courses for undergrads
~1960 "A Proton/Neutron is indivisible" - Physics consensus
~1990 "You cannot have structures smaller than half of the light wavelength." - Physics consensus photolithography