Hi everyone, Recently I randomly thought of a thought experiment of something going faster than light, along the lines of a shadow or some other "non-information carrying object". In this case it would be an empty seat. The idea is to take 800 million and one chairs of half a meter breadth and put them in a row. Then take 800 million people and make them sit on the first 800 million chairs. Then the trick is to get them to simultaneously stand up and move to the seat next to them in 1 second. The idea is that the empty seat now traveled 400 million meters in 1 second. Hopefully the general idea is clear. I was discussing the idea with some people and it seemed they had a serious (theoretical) problem with the set up. Basically their question was about how one gets everyone to switch seats at the same time. I proposed giving everyone a clock before going to their seats (synchronized clocks) then everyone moving to their seats and performing a calculation to re-synchronize their clock with the clock of the person on the first chair. Then everyone switches seats at a particular time. This argument was not convincing, but time constraints made it so the people I was discussing with could not explain the exact obstruction to me. So I guess my question is if you could explain what the problem with this thought experiment is. More clearly, I want to know why this experiment is really theoretically flawed? Of course if you think it is possible and can maybe fix the problem (that I do not quite see) then that would also help. I hope the question is at least clear, thanks in advance.