Jacob Bekenstein's Universes: From Black Holes to Modified Theories of Gravity

Abstract: Jacob Bekenstein's pioneering contributions to the foundations of Gravity cover a broad range of scales, from Black Holes to the entire Universe. He is well known as the father of Black Hole Thermodynamics and the inventor of the TeVeS modified gravity theory. I reflect here on my interaction with him, from the time he supervised me for my MSc project at Ben-Gurion University in the early 1980s to his sabbatical visit at UCL in 2014, about a year before he passed away (sadly just a month before the first LIGO discovery of Gravitational Waves from a Binary Black Hole). His quote "I feel more comfortable in the world if I understand why things are happening" reflects the way he viewed the world as a Physicist as well as his personal belief. He also allegedly said "Sometimes theories are smarter than their inventors".