Thought Experiment 1: I shoot a laser into space for one second. Just before I let off the trigger, the face of the beam is ~186,000 miles away. What happens to the beam when I let off? Does it instantly cease to exist? Does the tail compress into the stopped head and go poof :)? Does that 186,000 mile long beam keep going until it hits something? Or, something completely different? Thought Experiment 2: I devise a perfectly mirrored containment vessel such that when I shine a laser into the container, all the bounced beams intersect at the exact same point inside. What happens at that point? In other words, how do the beams interact, or do they at all, or is any interaction maybe related to and dependent on the frequency of the beam? Thanks in advance for teaching me.