system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Can a box in a box, in a box, in a box, break the speed of light from a relative view of being outside the box?

You as an observer are outside these transparent boxes.   Inside the biggest box is a smaller box, that travels the length of the container box at 99.999% the speed of light.  Inside that box is another box, moving at 99.999% the speed of light.  Inside that box is another doing the same thing.

From each box's perspective, it is not breaking the speed of light.  Relative to its own environment, it is obeying the laws of physics, assuming it has the energy to get to that speed, correct?  

Now, as an outside observer of these boxes, the smallest box would be moving far faster than the speed of light, would it not?  Or does the act of observing the boxes limit their speed?  

Is their top speed dependent on whether the boxes are transparent or not?
gpt
No, it can't break the speed of light.

The reason is because of time dilation.

Imagine you're standing outside the outer box. The passage of time which the inner box experiences is much slower than the passage of time that you experience. So although from it's own point of view, it's going 99.999% the speed of light inside its container box, you will see it moving much slower relative to its container box because of time dilation, and that means you will see it not exceeding the speed of light relative to you.