The question of the correct form of the stress tensor and the linear momentum of light in dielectric media has been discussed for over a century, especially with regard to the Abraham and Minkowski formulations. Based on simple models and available experimental results, and consideration of the momentum in the field as well as the medium in which the field propagates, it will be argued that the Abraham and Minkowski momenta are both correct but that they describe different physical quantities.

Dr. Milonni graduated summa cum laude from Niagara University in 1969 with a B.S. in physics. He then commenced graduate studies, where he completed a Ph.D. in theoretical physics in 1974. He was a research physicist at the Air Force Weapons Laboratory (1974-1977), a senior staff engineer at the Perkin-Elmer Corporation (1977-1980), and a professor of physics at the University of Arkansas (1980-1985) before becoming at staff member (1985-2005) and a laboratory fellow (since 1994) in the Theoretical Division of the Los Alamos National Laboratory. He is currently a guest scientist at Los Alamos and a Research Professor of Physics at the University of Rochester. Dr. Milonni’s primary research interests have been in quantum optics and electrodynamics, especially in connection with the quantum and fluctuation properties of electromagnetic radiation. In addition to many research papers, he has authored several books, including Lasers (1988, with J.H. Eberly); The Quantum Vacuum. An Introduction to Quantum Electrodynamics (1994); Fast Light, Slow Light, and Left-Handed Light (2005); and Laser Physics (2010, with J. H. Eberly). Dr. Milonni was awarded the 2008 Max Born Award by the Optical Society of America "for exceptional contributions to the fields of theoretical optics, laser physics and quantum mechanics, and for dissemination of scientific knowledge through authorship of a series of outstanding books".