1. Pretend that a person can walk only at a certain paceno faster, no slower. If you time their uninterrupted walk across a room of known length, you can calculate their walking speed. If, however, they stop momentarily along the way to greet others in the room, the extra time spent in their brief interactions gives an average speed across the room that is less than their walking speed. How is this similar to light passing through glass? In what way does it differ?

2. When astronomers observe a supernova explosion in a distant galaxy, they see a sudden, simultaneous rise in visible light and other forms of electromagnetic radiation. Is this evidence to support the idea that the speed of light is independent of frequency?

3. What astronomical event would be seen by observers on the Moon at the time Earth experiences a lunar eclipse? At the time Earth experiences a solar eclipse?