1915
Sigmund Freud's rational mind realises that it is not his complete psyche.

1929
Werner Heisenberg's Uncertainty Principle says you can never know everything about anything.

1945
Atom bombs tested on live cities.

1953
DNA structure revealed; as well as a means of altering it: the H-bomb.

1957
Sputnik leaves planet Earth.

1964
J.S. Bell finds that small events can instantaneously affect things miles away.

1969
First person walks on the moon.