Einstein follows the development with great interest but at a skeptical distance. He is particularly bothered that the uncertainty of the description should be elevated to a formal principle.

Heisenberg defends himself against Einstein's attacks on the uncertainty principle. Even if one assumes that the good Lord knows the location of particles more precisely than the uncertainty principle allows, this does not alter the fact that the result of experiments in quantum mechanics cannot be deterministically predicted. However, it is not right to use physics to describe more than the context of the experiments.