Self-tying shoes Self-tying shoes Self-tying shoes (also known as "self-lacing" or "power laces") are designed to automatically tighten once the user puts them on. Such shoes were initially depicted in the 1989 science fiction film "Back to the Future II". In April 2009, Nike filed a patent for self-lacing shoes, with a design that bears a resemblance to those worn by Marty in the film "Back to the Future II", raising speculation among fans about a possible debut of self-lacing shoes. In 2014, Tinker Hatfield, the designer of the original Nike shoes as depicted in "Back to the Future II", indicated that
Quantum mechanics of time travel Quantum mechanics of time travel Until recently, most studies on time travel are based upon classical general relativity. Coming up with a quantum version of time travel requires us to figure out the time evolution equations for density states in the presence of closed timelike curves (CTC). Novikov had conjectured that once quantum mechanics is taken into account, self-consistent solutions always exist for all time machine configurations, and initial conditions. However, it has been noted such solutions are not unique in general, in violation of determinism, unitarity and linearity. The application of self-consistency to quantum mechanical time machines has taken