New Physics Magnified in Spinning Black Holes

Q uantum gravity refers to a group of theories—string theory, for example—that aims to reconcile the microscopic world of quantum physics with the macroscopic world of general relativity. Many experimental tests of quantum gravity have been proposed, but the relevant effects might be too tiny to detect. Now theoretical work by Grant Remmen at the University of California, Santa Barbara, and his colleagues shows that celestial objects called extremal Kerr black holes are highly sensitive to quantum gravity [1]. Precise observations of these bodies could therefore reveal evidence of new physics.