Some people think that time is an illusion of consciousness. Phyiscally, there do not appear to be any time dependent equations. It is generally our experience of cause and effect which makes us feel that B, caused by A, must follow A. Although it feels intuitively correct, we should be suspicious because these are our perceptions of events 'caused' by us, or by other creatures. These actions may display cause and effect, but we are a part of the equation. Does the 'natural' occurrence of a rock hitting another rock show cause and effect. Does it depend on it being observed? (Does a tree falling in a forest make a sound?!)