In 1927, Heisenberg showed that uncertainty is inherent in quantum mechanics. ...Dirac was right. It is very hard to form a mental picture of the atom without introducing irrelevant hidden variables.
The play repeats their meeting three times, each with different outcomes. As Heisenberg, the character, states: "No one understands my trip to Copenhagen. Time and time again I've explained it. To Bohr himself, and Margrethe. To interrogators and intelligence officers, to journalists and historians. The more I've explained, the deeper the uncertainty has become."
In his 1930 text The Principles of Quantum Mechanic. Paul Dirac, a colleague of Heisenberg, contrasted the Newtonian world and the Quantum one: "It has become increasingly evident… that nature works on a different plan. Her fundamental laws do not govern the world as it appears in our mental picture in any direct way, but instead they control a substratum of which we cannot form a mental picture without introducing irrelevancies."
I think that today's search for hidden variables is a misguided attempt to validate some flawed mental picture. They are usually not explicit about their faulty assumptions.