Hi - I’m new here and I'm probably a bit of an impostor in that I’m not a physicist, scientist or even academic. I’ve been trying to increase my understanding of Relativity and often see a light clock experiment that is used to demonstrate time dilation. Given the extent that this particular experiment is used, I expect it has been thoroughly analysed and validated. Unfortunately, I can see an obvious flaw in the experiment. Am I wrong, or am I right? The experiment: First scenario -There are two identical, synchronised light clocks, A and B. In each clock a blip of light bounces vertically between two horizontal mirrors. The clocks record a second every time their blip hits a mirror. When both clocks are stationary, both blips hit the mirrors at exactly the same time and the clocks show the same time to a stationary observer (I know that stationary means uniform motion). Second scenario - Clock A and the observer remain stationary but clock B moves in a horizontal direction. The light blip in clock B now has to travel both horitzontaly as well as vertically and has to cover a greater distance to hit each mirror. Clock B therefore now runs slower than clock A. The flaw? The blip is light, and light wouldn’t inherit the velocity of the moving mirrors of clock B in the second scenario. It would want to continue bouncing vertically in a stationary position. For example, if the horizontal mirrors were spinning discs in a stationary clock, the blip would still bounce up and down vertically. In the Second scenario the blip would only move in the horizontal direction of the moving mirrors if it was fired from whatever created it at an angle from the vertical. This means the clocks are no longer identical. Effectively, the mirrors are now further apart in clock B than they are in clock A. To look at it in another way, if the blip is fired at an angle from the vertical, the mirrors don’t even need to be moving. A series of stationary mirrors could be positioned to bounce the zig-zagging blip. In fact, two long stationary mirrors could be used for both clocks. All this experiment is proving is that a direct route is shorter, and therefore quicker, than an indirect route. Don’t see where Relativity comes in to it. I hope I have explained things clearly enough that you can understand what I mean.