JDude13 said:
The meaning of the phrase "tachyon's time" is sort of ambiguous since a tachyon can't have its own inertial rest frame...it is true that if you use the same method that's used to calculate proper time along a slower-than-light particle's worldline, for a tachyon you'll get an imaginary value of time (but you can also think of this in terms of a real spatial distance rather than a time--see time-like vs. space-like intervals)JDude13 said:
People do say this but again they're speaking in a sort of ambiguous way...what is true is that if a tachyon is moving faster than light but forward in time in the inertial rest frame of one slower-than-light observer, then you can find another slower-than-light observer who measures the same tachyon moving backwards in time (here 'moving backwards in time' is shorthand for the idea that in this observer's frame, the event of a tachyon signal being received happens at an earlier time than the event of the signal being sent, due to the relativity of simultaneity). One consequence of this is that if it were possible to send FTL signals with tachyons, and if relativity's postulate that the laws of physics work the same in all inertial frames was still correct, then it would be possible to for two inertial observers to bounce a tachyon signal back and forth in such a way that observer #1 sends a tachyon message to observer #2, observer #2 sends a tachyon signal in reply, and observer #1 actually receives the reply before he sent the original message, so if the reply was just a copy of his original message then he can send a message into his own past using this method (see this section of the tachyon wiki article).JDude said:
Tachyons are hypothetical particles that travel faster than the speed of light. They are a concept in theoretical physics and have not been observed in reality.
Tachyons are believed to have imaginary mass and therefore, according to special relativity, they would experience time and length in reverse. This means that from our perspective, tachyons would appear to be moving backwards in time and their length would contract rather than expand.
No, tachyons are not consistent with Einstein's theory of relativity. According to this theory, nothing can travel faster than the speed of light, and tachyons violate this fundamental principle.
There is currently no evidence or theoretical basis to suggest that tachyons can be used for time travel. In fact, the concept of tachyons raises many paradoxes and contradictions in the theory of time travel.
If tachyons were to exist, it would fundamentally change our understanding of physics and the laws of the universe. It could potentially open up new avenues of research and lead to a better understanding of concepts such as time, space, and the speed of light.