Now comes the Einstein–Podolsky–Rosen entangled state. Now I see faces, people saying, "Oh..?" Don't worry! When you go to the concert, you don't nee… - Alain Aspect

The most remarkable feature of Bell's work was undoubtedly the possibility it offered to determine experimentally whether or not Einstein's ideas could be kept. The experimental tests of Bell inequalities gave an unambiguous answer: entanglement cannot be understood as usual correlations, whose interpretation relies on the existence of common properties, originating in a common preparation, and remaining attached to each individual object after separation, as components of their physical reality.

The main difficulty in popularizing quantum physics is that we do not really know how to make images of it in our world. In this sense it is really counterintuitive.

[In] 1964... John Stewart Bell... discovered inequalities that allow an experimental test of the predictions of local realism against those of standard quantum physics.