Based on my current knowledge on physics (which is not a lot), a tachyonic antitelephone is a hypothetical device that will allow information to travel back in time, created based on the theory of the tachyon which is a hypothetical faster-than-light particle. But then I was extremely confused by the concept of sending a signal to your own past. To send a signal to the past the speed of the particle must exceed infinity. A particle at infinite speed could send a message to anywhere in the universe which no delay at all, but to make the delay into a negative number, the speed of the particle will need to travel faster than infinite which as we know is impossible. So the part that I'm confused with is that since the speed of light is finite, then if the particle is faster than light but slower than infinite, how is it possible to send a signal to the past?
Sorry for the inconvenience, I'm just a random 4th grade kid trying to learn basic physics, sorry if this doesn't make any sense.