The paper discusses the conjecture that the duality between color and kinematics observed at tree level in gauge theories persists to all quantum loop orders. This duality allows for the straightforward derivation of multiloop gravity amplitudes from gauge-theory amplitudes. The authors test this conjecture using the three-loop four-point amplitude of $\mathcal{N}=4$ super-Yang-Mills theory, showing that it can be arranged to satisfy the duality and that the corresponding amplitude of $\mathcal{N}=8$ supergravity can be obtained by taking double copies of the gauge-theory diagram numerators. They also provide a non-supersymmetric two-loop test based on pure Yang-Mills theory, resulting in gravity coupled to an anti-symmetric tensor and dilaton. The key tools used are the unitarity method and maximal cuts, which simplify the study of multiloop amplitudes. The authors argue that the duality has important implications for the ultraviolet behavior of quantum gravity theories and suggests a novel structure related to compositeness.The paper discusses the conjecture that the duality between color and kinematics observed at tree level in gauge theories persists to all quantum loop orders. This duality allows for the straightforward derivation of multiloop gravity amplitudes from gauge-theory amplitudes. The authors test this conjecture using the three-loop four-point amplitude of $\mathcal{N}=4$ super-Yang-Mills theory, showing that it can be arranged to satisfy the duality and that the corresponding amplitude of $\mathcal{N}=8$ supergravity can be obtained by taking double copies of the gauge-theory diagram numerators. They also provide a non-supersymmetric two-loop test based on pure Yang-Mills theory, resulting in gravity coupled to an anti-symmetric tensor and dilaton. The key tools used are the unitarity method and maximal cuts, which simplify the study of multiloop amplitudes. The authors argue that the duality has important implications for the ultraviolet behavior of quantum gravity theories and suggests a novel structure related to compositeness.