[psychphysic]

Physics does not answer why questions it's about modeling and predicting.

QM and esp. Schrödinger equation has way too many shortcomings for someone to claim it's easy to understand.

You're question about maximise, minimise and deritive set to 0 is a bit bizarre. Is it genuine? If so it's that it's about stationary points.

[Koshkin]

> Physics does not answer why questions

Well it does, but often it takes a more fundamental theory than where the question was posed.

On the other hand, an answer may involve logic and/or a mathematical derivation which is not so different from calculation, so where intuition ends and “shut up an calculate” begins is not all that clear and may depend on the level of expertise.

[psychphysic]

Since we don't (yet) have a fundamental theory it stands.

Not only that but the shut up and calculate mentality is still the most dominant one within physics.

Should string theory turn out to be the fundamental theory then it's possible the 'Why' will be that's the geometry of our universe. Which is not more for filing than tweaked constants.

Unfortunately no physics won't tell us Why. That's a question for philosophy.