At a glance we think that quantum mechanics is a poor replacement of classical mechanics. However, a more rigorous examination reveals a startling reality: classical mechanics is nothing other than an approximation of quantum mechanics.
The certainty expressed by classical mechanics is merely a shadow, and conformity with experiment arises as a consequence of the fact that a macroscopic object consists of many individual atoms deviating from the unobserved average behavior.
Instead of a collection of physical principles, one for the macroscopic and the other for the microscopic nature; there is only one set, and quantum mechanics reveals our best effort to date to formulate it
