First principles

[ali_khan]

Why do we call quantum physics an ab initio model? Why do we call classical mechanics an ab initio model? Is classical electromagnetism an an ab initio model (and if it is one, what are its first principles)?

Quantum physics is ab initio because it starts with some basic rules like the state of a system is described by its wave equation, and that equation tells us how that system changes with time. And when we measure something, we get specific values with certain probabilities. Once we accept these basic rules, we can predict the behavior of atoms, molecules, and subatomic particles. Similarly, classical mechanics is based on Newton’s three basic laws of motion. Based on those laws or first principles, we can sufficiently predict the motion of stars, or the acceleration of a car etc.

The answer for the 3rd question is: Yes, classical electromagnetism is also an ab initio model, and its based on the first principles of Maxwell’s and Lorentz’s laws which describe how magnetic and electric fields are created and change, and how these fields push charges.

• This topic was modified 2 weeks, 3 days ago by ali_khan.

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