Hi! I have been pondering a scenario involving a paradox with length contraction. I brought it up with my physics professor, and I somewhat understand what is supposed to happen, but I'm still somewhat confused, so I was wondering if you could help me figure out what is going on. In this scenario, a meter stick is travelling at relativistic speeds above the flat ground. On the ground, there is a setup where two laser tripwires (consisting of a laser emitter and receiver), each located one meter apart, are lying in the path of the meter stick. When both lasers are tripped simultaneously (as in the receivers simultaneously detect that there is no light entering it), an electrical signal is transmitted that turns on a light. So, from what I understand, when the meter stick is travelling extremely fast, it experiences length contraction (say, it is travelling fast enough to contract to 0.9 meters), and so it will never obstruct the path of both lasers simultaneously; therefore, in the frame of reference where the lasers are still and the meter stick is moving, no electronic pulse will be created, and so the light will not turn on. However, in the frame of reference that the lasers are moving and the meter stick is still, the distance between the lasers will contract (say, to 0.9 meters), so both lasers will be obstructed simultaneously, and so the light will turn on. When I posed this to the professor, he said that the observation in both frames of reference should be analogous because causality must be preserved; therefore, the light will either turn on in both scenarios, or will not remain in both scenarios. He said that, while the length contraction will occur in both scenarios, the time dilation caused by special relativity should "balance this out" so that the same result occurs regardless of the frame of reference. However, I am still somewhat confused. In this scenario, how does time dilation cause the light to behave similarly in both frames of reference? Can anyone explain what is going on in this scenario that prevents causality from being violated? Thank you!