If you could send a text message faster than the speed of light, you could theoretically warn yourself not to send it. This is the mind-bending concept of the Tachyonic Antitelephone. In theoretical physics, this is a hypothetical device that uses "tachyons"—particles that travel faster than light—to communicate with the past. According to Einstein's Special Relativity, there is no universal "now." Time is relative to your speed. If a particle moves faster than light (FTL), there will always be

Groundbreaking tachyon discovery brings time travel closer to reality – Lifeboat News: The Blog

Tachyon. A tachyon is a subatomic particle that exists naturally at speeds faster than light, and can often be associated with time travel or occur as a byproduct of time warp. Tachyons exist either naturally, such as in tachyon eddies, such as those found in the Bajoran system, or they can be produced artificially, such as in tachyon detection networks and temporal transponders. They can also exist as byproducts of the use of many technologies, such as cloaking devices and transporters. Sources

Starfleet Academy. Courses. Temporal Mechanics. Time Travels. Tachyons: Tachyons exist naturally, as in the tachyon eddies of the Bajoran system, or can be produced artificially, as in tachyon detection arrays and temporal transponders. They can also exist as byproducts of various technologies, such as cloaking devices and transporters. These allow for time travel and travel to different realities. Star Trek Starfleet Command | Starfleet Academy