Max Planck (1857-1947), the discoverer of the famous Quantum Theory, is another eminent physicist who advocates Realism. In the beginning of his autobiography, he writes: "The fact, which led me to science and filled me with enthusiasm for it, from my youth onwards, and which is by no means self-evident, is that our laws of thinking coincide with the lawfulness in the course of impression which we receive from the external world, so that man is enabled to obtain enlightenment on the lawfulness by means of pure thinking. In this, it is of essential significance that the external world represents something independent of ourselves, something absolute that we are facing, and the search for the laws that hold for this absolute seems to me the most satisfying task for the life's work of a scientist."[1]
Thus the reality of the external world is presupposed by Planck as absolute and independent of ourselves.