Dr. Woon Siong Gan completed his PhD at the age of 24, and is one of the founders of condensed matter physics. He was the first to introduce transport theory into condensed matter physics, and coined the term “transport theory” in 1966, during his PhD studies at the physics department of Imperial College London. Today, transport theory is the key foundation of the theoretical design of new materials and enjoys a status in condensed matter physics similar to that of Yang Mills theory in particle physics.  His PhD thesis (1969) employed a statistical mechanics approach to describe phase transition and ultrasound propagation in semiconductors in the presence of high magnetic fields and low temperatures instead of the usual method of electron-phonon interaction from many body theory. Accordingly, his thesis also played a part in the founding of condensed matter physics.  In 2007 he introduced a gauge invariance approach to acoustics fields, a milestone in the history of gauge invariance in physics.  Recently he has also introduced curvilinear spacetime for the treatment of nonlinear acoustics; a suitable choice due to the curved paths of high-intensity acoustic fields.   Dr. Woon Siong Gan authored the books Acoustical Imaging: Techniques and Applications for Engineers, published by John Wiley & Sons in 2012, and New Acoustics Based on Metamaterials, published by Springer in 2018.  This is his third book, Gauge Invariance Approach to Acoustics Fields, published by Springer. His current research interests are in transport theory approaches to phase transition, quantum acoustic metamaterials, and curvilinear spacetime approaches to nonlinear acoustics.