I want to know the answer to the following question:
What is the old Quantum  theory?
All the background I'm provided with is that "Outside the realm of quantum physics, the various aether theories in classical physics, which supposed a "fifth element" such as the Luminiferous aether, were nullified by the Michelson-Morley experiment—an attempt to detect the motion of earth through the aether.". Is that enough to answer the question?
Answer: no