Question: Do we really need to spend too much time on Bell's theorem/test when there are numerous/easier proofs of quantum entanglement? The numerous/easier proofs are: - Almost all experiments in which two photons are generated via a) SPDC (Delayed Choice Quantum Eraser, Mach–Zehnder interferometer et el.) b) Fiber coupler c) Quantum dots d) Atomic cascades (used in the original Bell's test/theorem) For example in DCQE (http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser): [Broken] one of the twin/entangled photon's path can be manipulated to get (or erase) which-way information and the effect can be instantaneously seen on its remote twin in term of the patterns the twin would make on the screen. Is there a way/logic that LHV (local hidden variable) theory can explain this? Are there any loopholes? Spending time on Bell's theorem might be useful as it serves as additional/secondary proof and it proves/confirms the cosine relationship (from QM theory) however do we need to argue/doubt the existence of Quantum Entanglement?