| NEUTRINO | Subatomic particle said to travel at the speed of light (8) |
| SONIC | Very pleasant briefly to travel at the speed of sound (5) |
| MISSEDTHEBOAT | Failed to grab a chance to travel, at the docks (6,3,4) |
| ECHOES | They travel at the speed of sound |
| MIGRATE | Travel at the speed of a Soviet aircraft? (7) |
| MACHISMO | At the speed of sound, two seconds of manliness (8) |
| PHOTON | Quantum of electromagnetic radiation that travels at the speed of light (6) |
| GOBEHIND | Big hen to do badly, and so travel at the rear (2,6) |
| BEAM | It travels at the speed of light |
| CHASTISE | Beat the speed of light? Speed is boring! (8) |
| TRANSONIC | No trains running at the speed of light or at the speed of sound (9) |
| SUBSPACE | In science fiction, a hypothetical method of communication which is faster than the speed of light (8) |
| RAPIDITY | With the speed of light, dip it, bundled up, into (8) |
| COLANDER | What will strain old spacecraft chasing the speed of light |
| CONCORDE | Name of a former jet airliner that was used for commercial travel at supersonic speeds of around 1,350 mph (8) |
| AVOGADRO | Audio-visual at head office on travel at Rome halfway meeting Italian scientist (8) |
| INTERVAL | Break at home? Travel at sea (8) |
| CULDESAC | Clued as "moving with the speed of light", no two ways about it (3-2-3) |
| TRIATOMIC | Water is converting it to air, absorbing mass at the speed of light (9) |
| OPERATIC | Old film about time travel at inauguration is theatrical (8) |
