The discussion centers on the nature of photons and their relationship to spacetime, specifically questioning whether photons are vibrations of a spacetime lattice. Participants argue that spacetime is not a lattice but a smooth manifold, and photons are better understood as excited states of the electromagnetic field, distinct from gravitational waves. The conversation highlights that while both light and gravitational waves travel at the speed of light, they are fundamentally different in their properties and effects on spacetime. Gravitational waves are described as distortions of spacetime, whereas electromagnetic waves do not cause such curvature. The consensus emphasizes the need for precision in terminology and the distinction between electromagnetic and gravitational phenomena.