length expansion

Hello    Today, I would like to take a look at the questions posted at https://physics.stackexchange.com/. The contents are as follows. There is an iron bridge. This bridge cannot withstand the weight of the entire train, but if it only has to support part of the train as shown in Figure 1 below, it can do it. Figure 1. Non-relativistic consideration, if only a part of the train is on the iron bridge, the iron bridge will not collapse Therefore, when the train runs slowly, it is placed only on a part of the bridge, so the bridge does not collapse. (Click below to see the original.) However, if the length contraction is correct, it will be as shown in Figure 2 below. The train is contracted, the entire train is placed on the bridge, and the bridge must collapse. Figure 2. When the observer on the ground sees it, the entire train has come up and the iron bridge must collapse (Length contraction) However, from the standpoint of the person on the

   Today, let's look at the continuity in the nature of light. There are several important properties of light. The fact that the velocity in a vacuum must be constant, and that the speed is the same in all directions, can be explained by the term "constancy of the speed of light". But there is one thing more fundamental than this. The path of light should be ' continuous '. Can the photon disappear at some point while it is transmitting in space, and can it reappear at another point? In relativity, this never happens. This is an extraordinary science, beyond modern science. Therefore, these things cannot be accepted or recognized in the theory of relativity. This is a series of posts. It is better to read the following article first. Understanding the principle of invariant light speed 01 When we talk about light in relativity, there are a few things that we should basically assume. This is the constancy of speed of light proposed by Einstein, bu