" One quantum theory of the atom is great, but two are a problem, especially since they both reproduced the right spectrum of hydrogen. The two theories could not have differed more, as reflects the philosophies of their discoverers. Einstein, de Broglie, and Schrödinger were realists. Even if there were mysteries, they believed an electron was real and somehow existed as both wave and particle. Bohr and Heisenberg were enthusiastic anti-realists who believed we have no access to reality, only to tables of numbers which represent the interactions with the atom, but not the atom directly. "

― Lee Smolin , Einstein's Unfinished Revolution: The Search for What Lies Beyond the Quantum