This is a writing exercise for the student, and answers will vary.
Work Step by Step
Dear Grandma, Einstein's theories of relativity tell us about the nature of space and time. Scientists use their experiments to prove his ideas about how time intervals get longer for moving objects and how lengths get shorter. They're verifying Einstein's theories every day out there. It sounds unbelievable, but evidence for time dilation comes from experiments in particle accelerators, labs, and on airplane flights. Ample evidence is also provided by the Global Positioning System (GPS), which depends on synchronizing clocks. This is discussed on pages 666-667 of my textbook. Einstein's ideas about mass and energy are also proven every day in nuclear power plants. I'm excited, and plan to study Einstein's ideas in more detail. It's mind-blowing!