Allow me to elaborate it further. Let's say ship A and ship B are trying to find each other in space. Ship A uses its passive radar to scan the sky to detect ship B's heat signal. But I'm thinking, because the speed of radio wave is only equal to light speed. So in order for ship A to avoid detection, it must be outside the 300,000 KM range, because at that distance ship A could only see ship B's past location (at least 1 second ago). Is that correct? So if a ship wants to maneuver in space to avoid detection from the enemy's radar, it must be far enough so that the light speed lag could conceal its current position?
I'm asking this because I think, in a realistic sense, laser weapons can fire a beam at light speed. So it's rather pointless to try to maneuver within that 300,000 KM range. Outside that range, the light speed lag will provide both side with a change to avoid detection and getting hit by beam weapons?