| Albert Einstein theorized that the speed of gravity was around the speed of light, but no one proved it until now. |
| What would happen if the escape velocity of a planet were greater than the speed of light? |
| That is, an infinite amount of energy would have to be expended, via the accelerating force, to reach the speed of light. |
| The intense X rays from a solar flare travel to Earth at the speed of light, giving space weather watchers little time to react. |
| What little we know about this new subject consists of a few broad limitations such as the finiteness of the speed of light. |
| The emitted beta particle travels through air at close to the speed of light. |
