Linked from
The 169 pages that link to Quantum mechanics, each with the reason it gives.
Atomic physicsNarrower topic: Atomic structure and electron behavior require its rules.
Particle in a boxNarrower topic: The box is a simple model for its rules of states and measurement.
Wilhelm WienNarrower topic: Wien’s radiation research formed part of the path toward quantum theory.
Michio KakuNarrower topic: Quantum principles underpin the field theories Kaku studied.