• QUESTIONS BEFORE LECTURE 18

now think about these

• What is meant by "all news is old news" and "light takes time to travel?"
• When we receive light signals given off by a moving source, if the speed of light can't change from one observer to the other, what does change?
• How can two signals given off simultaneously in one frame, equal distances from an observer in the same frame, reach an observer in an relatively moving frame who was right with the first observer when the light signals were sent, at two different times?
• Compare the three ways to present the simultaneity Gedanken Experiment (book, lecture, video), which may seem different. Which works best for you?
• Compare the two ways to present the length contraction Gedanken Experiment (book, lecture), which are opposite to each other. Which works better for you?