"Perhaps surprisingly, we do in fact agree that AR and VR are related and that it is quite valid to consider the two concepts together. The commonly held view of a VR environment is one in which the participantobserver is totally immersed in a completely synthetic world, which may or may not mimic the properties of a real-world environment, either existing or fictional, but which may also exceed the bounds of physical reality by creating a world in which the physical laws governing gravity, time and material properties no longer hold. In contrast, a strictly real-world environment clearly must be constrained by the laws of physics. Rather than regarding the two concepts simply as antitheses, however, it is more convenient to view them as lying at opposite ends of a continuum, which we refer to as the Reality-Virtuality (RV) continuum."