Humanity's understanding of the universe radically altered with the advent of quantum mechanics in the early 20th century. The theory of quantum mechanics describes how nature behaves at or below the scale of atoms, and the road to that theory was littered with seemingly insurmountable obstacles. With us to discuss the development of quantum mechanics, and the major schools of thought represented by Neils Bohr and Albert Einstein, is Jim Baggott. Today we discuss many of the key players in the development of quantum mechanics, including Bohr, Einstein, Wolfgang Pauli, Werner Heisenberg, Erwin Schrödinger, Max Planck, and Max Born.