The following highly distinguished theoretical physicists have very kindly agreed to serve as PSI Patrons. They will each visit Perimeter Institute at least once per year to interact with and encourage the PSI students, and offer advice to PI on the quality and content of the program. Some of the Patrons will also give short lecture series.

**Yakir Aharonov**, Tel Aviv University and Chapman University, is one of the world's leading quantum theorists. He shared the 1998 Wolf Prize for his co-discovery of the Aharonov-Bohm effect. His research interests include nonlocal and topological effects in quantum mechanics and quantum field theory, and the foundations of quantum theory. He is a Professor at Chapman University and Professor Emeritus at Tel Aviv University.

**Philip Warren Anderson****,** Princeton University, is one of the world's most highly regarded condensed matter physicists. He shared the 1977 Nobel prize for his work on the electronic structure of magnetic and disordered systems, which allowed for the development of electronic switching and memory devices in computers. He has made pioneering contributions to many fields including antiferromagnetism and high-temperature superconductivity. He is Emeritus Joseph Henry Professor at Princeton University.

**James Daniel "Bj" Bjorken**, SLAC, is one of the world's most distinguished high energy particle theorists. His discovery of the scaling properties of high energy scattering amplitudes provided the initial evidence for the existence of quarks. He is Emeritus Professor at the Stanford Linear Accelerator Center.

**Stephen Hawking**, Cambridge University and Perimeter Institute, is one of the world's most famous living scientists. His proof that Einstein's theory of general relativity breaks down at the cosmic singularity, his theorems concerning the properties of black holes, and his demonstration that black holes should evaporate due to quantum effects provided much of the impetus for the field of quantum gravity in the 1970s. He also made seminal contributions to quantum cosmology, including the mechanism whereby primordial seeds for galaxies form in an inflationary universe. He holds the Lucasian Professorship of Mathematics at Cambridge University, as well as a Distinguished Research Chair at the Perimeter Institute. He is well-known for his popular expositions of theoretical physics, including the bestseller A Brief History of Time.

**James Peebles**, Princeton University, is one of the world's foremost cosmologists, and a founder of the modern big bang theory. In particular, with Dicke, Roll and Wilkinson, he provided the key interpretation of the observation of the cosmic microwave background. He performed pioneering calculations of big bang nucleosynthesis, and the pattern of anisotropy expected in the cosmic microwave background, according to various theoretical models. He was a founder of the cold dark matter theory of cosmic structure formation, and one of the first to advocate a cosmological constant (or "dark energy") as the explanation for various conundra regarding the interpretation of cosmological data.

**Sir Roger Penrose**, University of Oxford, is a renowned mathematical physicist, famous for his highly original and creative work in general relativity, including the theory of black holes and cosmology. He invented twistor theory, increasingly recognized as a very powerful tool for understanding the fundamental structure of unified quantum field theories. He holds the Emeritus Rouse Ball Professor of Mathematics at the Mathematical Institute, University of Oxford and is an Emeritus Fellow of Wadham College. He has published a number of bestselling popular science books including The Emperor's New Mind and The Road to Reality. He has an Erdös number of three.