It can't be seen, can't be felt, can't be heard and can't be smelt. It lies behind stars and under hills, and empty holes it fills. It comes first and follows after, ends life and kills laughter. What is it?

Rah is completing a school project on the expansion of fast food restaurants across the united states. she finds a map that shows a clear pattern of restaurants beginning in the east and expanding west. this map was most likely created using the technology of