Possible Clues:

• Einstein's topic
• Broadcast keeping one in television, it appears - that's the general theory
• Five among literati restored unknown theory
• Variable level holds key when reversing fundamental theory
• Trivial yet extraordinary subject of theory
• Subject of certain theories, complicated yet trivial
• Scientific theory of shared confidential knowledge not beginning to involve backstory
• Subject of a famous theory
• ''General'' topic of a 1916 Einstein book
• I try working with energy absorbing upcoming crucial theory in physics