Chris McMullen is a physics instructor at Northwestern State University of Louisiana. He earned his Ph.D. in phenomenological high-energy physics (particle physics) from Oklahoma State University in 2002. Originally from California, he earned his Master's degree from California State University, Northridge, where his thesis was in the field of electron spin resonance. He has published several papers on the prospects for discovering large superstring-inspired extra dimensions at the Large Hadron Collider, which is his area of specialization. Dr. McMullen published The Visual Guide to Extra Dimensions, Volumes 1 and 2, to share his passion for the geometry and physics of the fourth dimension. He also wrote these books, Full-Color Illustrations of the Fourth Dimension, Volumes 1 and 2, to help illustrate the geometry of a fourth dimension of space. Dr. McMullen was fascinated with a fourth dimension of space when he first read Rudy Rucker's introduction to the subject during high school. He happened to be working on his Ph.D. in particle physics when Arkani-Hamed, Dimopoulos, and Dvali wrote a famous technical paper motivating large superstring-inspired extra dimensions, which transformed the subject of the fourth dimension from philosophy to a plausibly experimental science. Dr. McMullen has published these general-audience books on the fourth dimension to share his passion for the math and physics of extra dimensions. One of his favorite sayings is: May your contemplation of a fourth dimension of space enhance the dimensionality of your thoughts.