| Answer | Crossword Clue |
|---|---|
| tachyon | hypothetical particle that travels faster than the speed of light |
| tachyons | hypothetical particle that travels faster than the speed of light |
| TACHYON | Hypothetical particle that travels faster than light |
| tardyon | a subatomic particle that travels slower than the speed of light |
| tardyons | TARDYON, a subatomic particle that travels slower than the speed of light |
| subspaces | (in science fiction) A hypothetical space-time continuum used for communication at a speed faster than that of light |
| subspace | (in science fiction) A hypothetical space-time continuum used for communication at a speed faster than that of light |
