James Daniel "Bj" Bjorken (born 1934) is one of the world's foremost theoretical physicists. He was a Putnam Fellow in 1954 and obtained his Ph.D. from Stanford University in 1959. He is Emeritus Professor at the Stanford Linear Accelerator Center, and was a member of the Theory Department of the Fermi National Accelerator Laboratory (1979-1989). Bjorken discovered what is known as Light-Cone Scaling, (or "Bjorken-Scaling") a phenomenon in the deep inelastic scattering of light on strongly interacting particles, like protons and neutrons (known as hadrons). This was critical to the recognition of quarks as actual fundamental particles (rather than just convenient theoretical constructs), and led to the theory of strong interactions known as quantum chromodynamics. In Bjorken's picture, the quarks become point-like, observable objects at very short distances (high energies). Richard P. Feynman subsequently reformulated this concept into the parton model, used by many physicists to understand the quark composition of hadrons when probed at high energies. The predictions of Bjorken Scaling were confirmed in the electroproduction experiments at SLAC in the early 1970's in which quarks were seen for the first time. The general idea, with small logarithmic modifications, is explained in Quantum Chromodynamics by "asymptotic freedom." Many believe Bjorken should have been awarded a Nobel Prize for this discovery, which was central to the revolutions in particle physics in the 1970's. Bjorken co-authored, with Sidney Drell, a classic companion volume textbook on Relativistic Quantum Mechanics and Quantum Fields that is still used by many practicing particle physicists.