Everybody knows that nobody’s perfect. But it still makes me smile to think that even smart people get it wrong, occasionally. Here are some instances where experts got it wrong in their own fields of expertise.

“I will ignore all ideas for new works on engines of war, the invention of which has reached its limits and for whose improvements I see no further hope.”
-Sextus Julius Frontinus, 40 - 103 AD

“Rail travel at high speeds is not possible because passengers, unable to breathe, would die of asphyxia.”
-Dionysius Lardner, 1793 - 1859

“Fooling around with alternating current is a waste of time. Nobody will use it, ever.”
-Thomas Edison, 1889

“There is not the slightest indication that nuclear energy will ever be obtainable.”
-Albert Einstein, 1932

“Computers in the future may weigh no more than 1.5 tons.”
-Popular Mechanics, forecasting the relentless march of science, 1949

Once in a while we are entitled to our own idiot moments. So don’t feel too bad about that coffee you spilled on your report or that wrong answer you gave in the meeting earlier. Just don’t keep repeating them and a few months from now those mistakes will be long-forgotten. Too bad I can’t say the same for the titans I just quoted above.

Other similar quotes here.

(Collection of quotes taken from this lecture in MIT Open Courseware)