"A theorist publishing in the 21 August Physical Review Letters offers a new explanation for this apparent conflict between the time-symmetry of the physical laws and the forward "arrow of time" we see in everyday events. When viewed in quantum terms, events that increase the entropy of the Universe leave records of themselves in their environment. The researcher proposes that events that go "backward," reducing entropy, cannot leave any trace of having occurred, which is equivalent to not happening." - Imabug from Bookmarklet