Max Karl Ernst Ludwig Planck was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918. Planck made many contributions to theoretical physics, but his fame as a physicist rests primarily on his role as the originator of quantum theory, which revolutionized human understanding of atomic and subatomic processes. Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research. Dr James Lees (introduction) is a Physicist, Author, and Science Communicator who studied at The University of York and Stanford. He works as a researcher and can be found giving talks and workshops across the UK at various educational festivals on a wide variety of scientific topics. He also has several other books including Physics in 50 Milestone Moments and Who Knew? Physics. Professor Marika Taylor (Series Foreword) is a Professor of Theoretical Physics and Head of School within Mathematical Sciences at the University of Southampton. Her research interests include all aspects of string theory, gravitational physics and quantum field theory. In recent years much of her work has been focused on holographic dualities and their implications. Marika's research has featured in such publications as Physical Review, Journal of High Energy Physics and General Relativity and Gravitation among others.