Laplace (1749 - 1827)
"An
intelligence knowing, at a given instant of time, all forces acting
in nature, as well as the momentary position of all things of which the
universe consists, would be able to comprehend the motion of
largest
bodies of the world and those of the lightest atoms in one single
formula, provided his intellect were sufficiently powerful to subject
all data to analysis; to him nothing would be uncertain, both past and
future would be present in his eyes" -
Quoted in "The Origins and Growth of Physical
Science", Vol 2, Hurd and Kipling (ed), p. 319.
More Laplace
The above statement was made based on the success of classical
mechanics in understanding terrestrial and celestial phenomena at that
time.
We now know that, in practice, the above assertion may fail even in
'classical' systems due to even minute errors that may be present in
the initial data -
chaos theory.