# Can information travel faster than speed of light in this situation?

I know the answer is no but I have a thought experiment that seem to be violating that. Imagine two persons living on two different planets namely A and C which are 10 light years apart. There is a planet in between, B, which is located exactly at the same distance from A and C. If two persons from A and C get on their hypothetical spaceships at the same time, that can travel around .99C, and move towards B, they can talk to eachother in around 5 years. Didn't information just convey between two persons at the speed of ~2C in this case?

• No, because the info is going between two people who used to be on A and C, but moved to B. No info went from A to C. Jun 5 at 16:10
• Two people being able to communicate with less time lag as they become very near each other does not make FTL communication. Jun 5 at 16:10
• Each party was able to communicate information in ~5 years. It's irrelevant to the physics if they "talk" in the middle. But good question though, got me to think for a minute. Jun 5 at 16:11
• So if I undestood right, a person or an object can actually recieve information faster than speed of light from another location in the universe but no information can travel between two points in space faster than speed of light. Correct? Jun 5 at 17:34
• The information about each person propagated to planet B at subliminal speed. Note also that at the same time in this context is a non-trivial statement, requiring passing information between A and C. Jun 5 at 18:01

So in your case, the travelers from A and from C arrive at B in just over 5 years. No violation there as you specified they were traveling at $$0.99c$$. We're good to this point.
Now if the traveler who started from A wants to relay a message back to his home world, he can do that. But his message will have to travel the 5 light-years between B and A, so that will take time. Exactly 5 years if he sends the message on a carrier that propagates at speed $$c$$. So a message relayed all the way from C to A by this process takes a bit more than 10 years, computed as a the bit more than 5 years it took the travelers to reach B from their respective home worlds and the 5 years it took for the relayed message to travel from B to A. That's consistent with the limit of 10 years that it would have taken if the message had been sent directly from C to A at the speed of light from the start. Still no violation.