Oppenheimer was less graceful about Einstein in private. He said Einstein had no interest in or did not understand modern physics and wasted his time in trying to unify gravity and electromagnetism. He stated that Einstein's methods in his final years had in "a certain sense failed him". Einstein in his last twenty-five years of life focused solely on working out the unified field theory without considering its reliability nor questioning his own approach. This led him to lose connections with the wider physics community. Einstein's urge to find unity had been constant throughout his life. In 1900, while still a student at ETH, he wrote in a letter to his friend Marcel Grossmann that, "It is a glorious feeling to recognize the unity of a complex of phenomena, which appear to direct sense perceptions as quite distinct things." In 1932, when questioned about his goal of work, Einstein replied, "The real goal of my research has always been the simplification and unification of the system of theoretical physics. I attained this goal satisfactorily for macroscopic phenomena, but not for the phenomena of quanta and atomic structure." And added, "I believe that despite considerable success, the modern quantum theory is still far from a satisfactory solution of the latter group of problems." Einstein was never convinced with quantum field theory, which Oppenheimer advocated. Oppenheimer noted that Einstein tried in vain to prove the existence of inconsistencies in quantum field theory, but there were none. In the 1960s Oppenheimer became skeptical about Einstein's general theory of relativity as the correct theory of gravitation. He thought Brans–Dicke theory to be a better theory. Oppenheimer also complained that Einstein did not left any papers to the institute (IAS) in his will despite the support he received from it for twenty-five years. Instead, all of Einstein's papers went to Israel.