Question

Why do quantum mechanics always prove correct for tiny objects also define quantum spin, quantum engtanglment and quantum cosmology.

Answer 1

• The author should not get hyped by the word quantum mechanics.. it's just like Newtonian mechanics or any other mechanics, just with the ability to carry out the mathematics at very basic and fundamental level which the normal Newtonian mechanics won't be easy to do .. as it will account many infinite terms and calculations.
• to make things easy and to understand the science behind the small fundamental things. We take help from quantum mechanics..
And it's always a great thing to notice that property as whole might be different from the one single thing contributing to that property. Like water .. wet is the property as a whole.. but is molecules are wet no how they could be.. thus at time the quantum mechanics will Answer very precisely but if you account the whole system. I doubt you would need better knowledge.. to hold upon the real property and science
•thus quantum mechanics is very powerful mathematics which is far very successful in describing the small tiny.. systems. Why you ask.. because we have developed it to do so.
Quantum spin is the spin number assigned to every electron, Fermions, and many other sub atomic particle
The quantum entanglement is a phenomenon in which the particle present at one point in space time spontaneously relates with particle present at different space time far apart than 3*10^8 m.. thus spookiness
Quantum cosmology is a science I believe which deals with studying the cosmos using the small and fundamental system.. by the standard physics chart .. :)