I am not sure whether GR corresponds to Mach Principle? -I heard that Mach Principle stimulated Einstein to inch closer to GR, but GR fundamentally does not correspond to Mach Principle. But many modern Quantum Gravity theories made an attempt to fix this gap between Mach Principle and the theories of gravitational field. Some modern Quantum Gravity Theories brand that they better manifest the spirit of Mach Principle. I wish I could know more about modern QG theories and Mach Principle. How did Albert Einstein like Mach Principle? -I heard that when Einstein was young, he really appreciated Mach Principle quite a lot, but in his later days, he changed his mind. I wish someone could ensure me whether or not that is true. Thanks. Happy New Year.