  In May of 1935, Einstein published with two co-authors the famous EPR-paper
about entangled particles, which questioned the completeness of Quantum
Mechanics by means of a gedankenexperiment. Only one month later, he published
a work that seems unconnected to the EPR-paper at first, the so called
Einstein-Rosen-paper, that presented a solution of the field equations for
particles in the framework of general relativity. Both papers ask for the
conception of completeness in a theory and, from a modern perspective, it is
easy to believe that there is a connection between these topics. We question
whether Einstein might have considered that a correlation between nonlocal
features of Quantum Mechanics and the Einstein-Rosen bridge can be used to
explain entanglement. We analyse this question by discussing the used
conceptions of "completeness," "atomistic structure of matter," and "quantum
phenomena." We discuss the historical embedding of the two works and the
context to modern research. Recent approaches are presented that formulate an
EPR=ER principle and claim an equivalence of the basic principles of these two
papers.
