light cone

• lightcone

light cone (plural light cones)

1. (relativity) In special relativity, the pattern describing the temporal evolution of a flash of light in Minkowski spacetime. This is modeled in 3-space using the two horizontal axes as spatial dimensions, while the vertical axis is time.
   • 1998, Hermann Bondi, Miranda Weston-Smith, editors, The Universe Unfolding, Clarendon Press, page 384:

     This gives the future light cone of the event. Similarly, you can define the past light cone—as the history of a spherical shell of light converging in on the event. All these spatial spheres, past and future, represent cross-sections through the space–time light cone, […]

2. Used other than figuratively or idiomatically: see light,‎ cone.