Answer Happy

3. Perceptions vs. Observations. A common confusion for students learning special relativity is between what a single observer would see with their eyes and what a system of local observers made with synchronized clocks will record. A single observer can only perceive information that has had time to reach them (they will only see events as they arrive). Consider a rod of proper length Lo, moving at speed v, relative to frame S. a. What is the length of the rod L, as measured by a system of observers with synchronized clocks in S? b. Now imagine there is a single observer, Ollie, in S. She is standing such that the rod is coming toward her head-on: there's a front end closer to her and a back end further away. Consider the light rays from the front end and back end of the rod as they enter her eyes. Explain in words and/or diagrams why the two light rays must have left the rod at different times. c. Explain in words why Ollie "sees" a length that is longer than what you found in (a).