Classical mechanics is a physical theory describing the motion of
macroscopic objects, from projectiles to parts of machinery and astronomical
objects, such as spacecraft, planets, stars, and galaxies. For objects
governed by classical mechanics, if the present state is known, it is possible
to predict how it will move in the future (determinism), and how it has moved
in the past (reversibility).
The "classical" in "classical mechanics" does not refer to classical
antiquity, as it might in, say, classical architecture. On the contrary, the
development of classical mechanics involved substantial change in the methods
and philosophy of physics.