Hello, I tried attaching this question in another forum's related thread, but no one has responded. I hope you don't mind me starting a new thread here. I think this forum is more suited to the question anyway. Here's the question: What are the energy and wavelength limitations of light? If you were to project the lowest energy beam possible from a fixed location and then accelerate away from that location travelling along the beam, what would happen? Would the beam always be hypothetically detectable? Is it possible for the energy level to drop so low that spin might be affected? Is it possible for the energy to drop so low as to affect the time dilation between the source and the accelerating vessel (essentially severing the reference frames)? What are the upper limits? If you were to project the highest energy beam possible and then accelerate toward it, what would happen? That is, if you're accelerating toward a high-energy beam at relativistic velocity, what unusual effects (if any) might you see?