Faster-than-light

Propagation of information or matter faster than the speed of light

Faster-than-light (superluminal or supercausal) travel and communication are the hypothetical propagation of matter or information faster than the speed of light in vacuum (c). The special theory of relativity implies that only particles with zero rest mass (i.e., photons) may travel at the speed of light, and that nothing may travel faster. Particles whose speed exceeds that of light (tachyons) have been hypothesized, but their existence would violate causality and would imply time travel.

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