What is time? Isaac Newton described it as absolute, but Einstein proved that time is relative, and, shockingly, that time and space are intricately interwoven. Now recent work in string theory and quantum gravity suggests that space and time may not be fundamental. If this is true, what new picture of reality will emerge? These questions and more were explored in the 2015 World Science Festival program “Time Is of the Essence … or Is It?” moderated by author Jim Holt and featuring physicist and philosopher David Z. Albert, theoretical physicist Vijay Balasubramanian, theoretical physicist and cofounder of the loop approach to quantum gravity Carlo Rovelli, and theoretical physicist and founding faculty member at the Perimeter Institute for Theoretical Physics Lee Smolin.