User: Can you explain the theory of relativity in laymen's terms?
Assistant: The theory of relativity is an idea proposed by Albert Einstein which states that all motion is relative to the observer. This means that the way we measure things, like time and distance, depends on how fast we are moving. At the most basic level, the theory states that things appear differently depending on the speed of the observer. For example, if you are standing still, a car moving by you would appear to be moving faster than a car that is also standing still. This theory is also used to explain why gravity works the way it does and to help explain the behavior of very large objects such as black holes.