A number of experimental tests of time orientability are described as well as clear experimental signatures from non time orientability (time reversal). Some tests are well known, while others are based on more recent theoretical work. Surprisingly, the results all suggest that time is not orientable at a microscopic level; even definitive tests are positive. At a microscopic level the direction of time can reverse and a consistent forward time direction cannot be defined. That is the conclusion supported by a range of well-known experiments. The conflict between quantum theory and local realism; electrodynamics with electric charges; and spin half transformation properties of fermions; can all be interpreted as evidence of time reversal. While particle-antiparticle annihilation provides a definitive test. It offers both a new view of space-time and an novel interpretation of quantum theory with the potential to unify classical and quantum theories.
The need to implement time reversal via complex conjugation in quantum theory has always been a bit of a puzzle. Why should i go to – i under temporal reflection when it has no spatiotemporal dimensions? I’ll provide a new insight into this question by showing how the little-appreciated “quantum-looking” classical Schrödinger equation of Schiller and Rosen faces the exact same problem. Since we know how to escape this problem classically, this observation teaches us one way to solve the problem quantum mechanically too. Big picture: if I’m right, the puzzle over quantum time reversal is connected to the interpretation of quantum theory.