¥Einstein's theory of relativity changed the
foundations of physics.
¥Many basic concepts, such as the relativity of space
and time, are a direct consequence of the "absoluteness" of the speed
of light.
¥The new theory is logically consistent and
mathematically very elegant.
¥The new theory "contains" Newtonian physics
as an approximation valid for speeds much smaller than the speed of light.
¥However, the new theory would be worthless if it
didn't agree with reality (i.e. experiments) better than classical physics.