# Apparent superluminal signals, is it as simple a variation on the following?

I know that astronomers observe jets that apparently move faster than light but really don't. I think I can simulate something that looks superluminal using just a bunch of x-mas lights and i am wondering if it is the same principle:

If I have, say, 1000 light bulbs each rigged to turn off and on at a specific time, then if by using a bunch of synchronized clocks, one for each bulb which send a signal like a billionth of a second after each other, then i could turn the first bulb on at time zero, the next bulb a billionth of a second later. an observe would see something that appeared to be a signal propagate so that the final bulb would turn on 1000 billionths of a second later (a micro second later) and if the thousand bulbs were a meter apart from its predecessor and successor, it would look like the signal crossed the kilometer in a millionth of a second, so a million kilometers per second or several times faster than light.

Now, no information is transmitted but how could the observer even know that a real signal was not transmitted over that kilometer? And is this simple demonstration basically what astronomers see but on a much smaller scale?

Note that one could simulate any speed in this way, the number of bulbs and distance crossed is completely arbitrary -- 1000 times light speed would also work although there is some speed at which the observer can actually see something happening and I think a human can't see anything that occurs in a micro second but around a millisecond humans can start to perceive things.

• This setup is more akin to superluminal group velocities en.wikipedia.org/wiki/… Commented May 4, 2021 at 7:45