First formulated in the early years of the 20th century, Einstein's theories of relativity overturned long-held concepts of space and time. They provided a radically new way of looking at the physical world and explanations for many questions unanswered by classical physics. Unfortunately, many laypeople consider relativity so abstruse and complicated that they despair of ever understanding it. In reality, the ideas, although profound, are quite simple.That simplicity is strikingly...