You don't truly understand relativity. Many people don't. Many grad students don't. Time Travel due to superluminous Transmission just looks like time travel if you are watching from any reference point in the universe using light, sound, particles or anything else made of Energy(which is pretty much everything we ever encountered.).
Relativity doesn't tell you what really happens, it only predicts what you see. It outright states that nobody can predict what really happens and it's only possible to observe the universe from a particular reference frame and use that to calculate what another another reference frame sees.
What really happens nobody knows(though there are a few intuitive theories), but what it looks like for Jane A is that you send the information into the future, the other guy reacts and then the response travels backwards in time. Then she can use light to see the guy respond to her message.
Jane B sees that someone send her data from the future, she responds and sends it back into the future. She cannot send it back to before the Data was send, because then it would end up at a different place in space.
Because if you look at it through relativity Space and Time is basically the same.
An easy example is this: You have two different guns and are on really far away hills. You fire Gun A vintage model named CauseTM and immediately afterwards the other one sees the muzzle flash and fires his Gun B a modern Effect brand. A blind man stands next to Gun B and says:"Whoa! Fist Effect, then Cause! Awesome, we have invented Time Travel!" Because without Ansibles we are all Blind. If we rely on slow light. Relativity is the Art of maneuvering our Huge Lightless world with only the slow echoes of Sound. Especially if you wanna communicate over large distances using these waves or want to calculate your position from them.
Re: Time Travel?
Relativity doesn't tell you what really happens, it only predicts what you see. It outright states that nobody can predict what really happens and it's only possible to observe the universe from a particular reference frame and use that to calculate what another another reference frame sees.
What really happens nobody knows(though there are a few intuitive theories), but what it looks like for Jane A is that you send the information into the future, the other guy reacts and then the response travels backwards in time. Then she can use light to see the guy respond to her message.
Jane B sees that someone send her data from the future, she responds and sends it back into the future. She cannot send it back to before the Data was send, because then it would end up at a different place in space.
Because if you look at it through relativity Space and Time is basically the same.
An easy example is this: You have two different guns and are on really far away hills. You fire Gun A vintage model named CauseTM and immediately afterwards the other one sees the muzzle flash and fires his Gun B a modern Effect brand. A blind man stands next to Gun B and says:"Whoa! Fist Effect, then Cause! Awesome, we have invented Time Travel!" Because without Ansibles we are all Blind. If we rely on slow light. Relativity is the Art of maneuvering our Huge Lightless world with only the slow echoes of Sound. Especially if you wanna communicate over large distances using these waves or want to calculate your position from them.