Some of these are probably apocryphal, but making predictions about the limits of technology is really hard:
Space travel is utter
- Popular Mechanics, 1949
X-rays are a hoax.
Kelvin, ca. 1900
I confess that in 1901 I
said to my brother Orville that man would not fly for fifty years. Two years
later we ourselves made flights. This demonstration of my impotence as a
prophet gave me such a shock that ever since I have distrusted myself and
avoided all predictions.
- Lee deForest, inventor of the vacuum tube, 1957
There is not the slightest
indication that [nuclear energy] will ever be obtainable. It would mean that
the atom would have to be shattered at will.
- Albert Einstein, 1932
That is the biggest fool
thing we have ever done. The bomb will never go off, and I speak as an expert
- Dr. Alfred Velpeaum, French surgeon, 1839
Bitcoin is definitely going to be trading at $10,000 or more and in wide use by the end of 2014.
- Many otherwise smart people, November of 2013
Superhuman machine intelligence is prima facie ridiculous.
- Many otherwise smart people, 2015
(Most of these from: https://www.lhup.edu/~dsimanek/neverwrk.htm)