In 1935 Einstein and his co-authors claimed to show that quantum mechanics led to logical contradictions. The objections exposed the theory’s strangest predictions.
Capsule history of quantum mechanics Starting in the seventeenth century, and continuing to the present day, physicists developed a body of ideas that describe much about the world around us: the motion of a cannonball, the orbit of a planet, the working of an engine, the crack of a baseball bat. This body of ideas is called classical mechanics . In 1905, Albert Einstein realized that these ideas didn't apply to objects moving at high speeds (that is, at speeds near the speed of light) and he developed an alternative body of ideas called relativistic mechanics . Classical mechanics is wrong in principle, but it is a good approximation to relativistic mechanics when applied to objects moving at low speeds. At about the same time, several experiments led physicists to realize that the classical ideas also didn't apply to very small objects, such as atoms. Over the period 1900–1927 a number of physicists (Planck, Bohr, Einstein, Heisenberg, de Broglie, Schrödinger, and others) developed an alternative quantum mechanics . Classical mechanics is wrong in principle, but it is a good approximation to quantum mechanics when applied to large objects. What is the nature of quantum mechanics? I'm not going to spend any time on the history of quantum mechanics, which is convoluted and fascinating. Instead, I will focus on the ideas developed at the end. What sort of ideas required twenty-eight years of development from this stellar group of scientists? Einstein's theory of relativity is often (and correctly) described as strange and counterintuitive.
Local realism must predict empirical Bell violations in a reasonable way to become a compelling causal explanation of reality. According to the paper at the link given below, it can now do that. On the other hand, theory, despite its wonderful statistical predictions, must transcend its infamous paradoxes to become a compelling causal explanation of anything. Unfortunately, paradoxes reduce to contradictions, and thus to nonsense. Take quantum superposition. Is this the simultaneous existence of mutually exclusive states or not? If it is, then we have a contradiction, and all further claims from theory fail to have meaningful interpretations. If superposition is something other than that contradiction, then what -- exactly -- is superposition? And let's take physical while we are at it. Defending theory as a causal explanation of reality requires that reality is not exclusively reality! Whoops. What -- exactly -- is so difficult about simply admitting when we have no sensible causal explanation for certain phenomena like Bell violations in EPR(B) experiments? In psychology, we know the answer to such questions. Our beliefs are evidence resistant. We thus predict that the rational threat from local realism to widespread beliefs -- its implication that reality might be mostly explained without appeal to antilocal mysticism -- will continue to be buried under reams of empirical observations stitched together by nonsense insinuations that that paradoxes are assets rather than contradictions. In any case, the paper below arguably formulates a theory of local realism that constitutes a causally valid description of reality. No nonsense required. Or, it could just be wrong. But it is waiting to be tested. Indeed, even existing data could bear on the empirical question if the theory is sound enough. See ** http://vixra.org/abs/1704.0078 ** Local Realism Explains Bell Violations (author Andrew P. Yake) - for a demonstration that all empirical evidence taken to support theory over local realism plausibly does the reverse. The article comprises 8 pages, 4 figures, 6 equations, 32 references, a graph of testable predictions, and two paragraphs that purport to expose how the Bell inequality misrepresents the local realistic predictions for the EPR experiment. Thoughtful feedback appreciated (apyake@gmail.com).
Wigner's friend scenarios expose a tension in quantum mechanics: an observer inside a laboratory obtains a definite measurement outcome, while an observer outside describes the laboratory as being in a superposition. The Frauchiger-Renner (2018) extension produces logical contradictions when agents use quantum theory to reason about each other. We show that the recursion-consistency functional K resolves these contradictions without modifying quantum mechanics. The resolution rests on a single physical fact: the friend's measurement creates ~10^20 environmental records inside the laboratory, driving K_rec to its minimum in ~10^-30 seconds. Wigner's description of the laboratory as a superposition is not wrong but incomplete: it omits the internal records that have already selected a definite outcome. The superposition description is operationally correct for Wigner (he cannot access the internal records) but ontologically incorrect (the records exist whether he accesses them or not). This distinction dissolves the Frauchiger-Renner contradiction, resolves the quantum eraser and delayed choice experiments as corollaries, and commits the framework to an ontic interpretation of the quantum state consistent with the PBR theorem.