If those aliens sent a light speed signal, they would have to wait 4 years to watch us recieve it in the "past". If the signal were faster than light, let's say instantaneous, they would simply see us recieve the message immediately rather than having to wait the 4 year travel time. So I think the answer is no, the message would not travel back in time
Edit: I forgot about the travel time for light from earth to the telescope. The instant message would be viewed arriving in the aliens 4 year old archived footage but still never traveled back in time. It does break causality though
psilosimian t1_j64j367 wrote
Reply to Sending a signal faster than light is time travel? by KingOfTNT10
If those aliens sent a light speed signal, they would have to wait 4 years to watch us recieve it in the "past". If the signal were faster than light, let's say instantaneous, they would simply see us recieve the message immediately rather than having to wait the 4 year travel time. So I think the answer is no, the message would not travel back in time
Edit: I forgot about the travel time for light from earth to the telescope. The instant message would be viewed arriving in the aliens 4 year old archived footage but still never traveled back in time. It does break causality though