Basic Considerations on the Interpretation of Quantum Mechanics A. Einstein (3)

This type of description is what is meant when speaking of the physical description of a "real outside world," whatever the selection of elementary building blocks (material items, field, etc.) on which such description is based may be. The legitimacy of this manifesto was not seriously questioned by physicists, as long as it appeared that everything present in such a description could in principle be established empirically in each individual case. The fact that this was an illusion was first proven in the field of quantum phenomena by Heisenberg in a way that was convincing to physicists. The term "physical reality" was now perceived to be problematic, and the question arose as to what it really was, what theoretical physics (through quantum mechanics) sought to describe, and whereto the laws it had established related. This question had quite different answers. To come closer to solving this, let us consider what quantum mechanics says about macrosystems, i.e., objects that we perceive to be "directly perceptible." We namely know that these objects and the laws which govern them can be represented by classical physics with significant, if not unrestricted, accuracy.