Steven Carlip Image source: Regents of the University of California Steven Carlip is an American physicist who wrote Quantum Gravity in 2+1 Dimensions Quotes by Steven Carlip in Time OneSimply put, we do not know what a quantum spacetime means. More about Steven Carlip University of California Quantum Gravity in 2+1 Dimensions, Cambridge University Press Mariah Carey Mary-Chapin Carpenter