> In an influential [2008] paper, Noah Linden, Sandu Popescu, Tony Short and Andreas Winter argued that the arrow of time can be explained in terms of quantum mechanical entanglement. As a physical system becomes entangled with its surroundings, it moves closer to equilibrium — and this one-way evolution determines time’s arrow.<p>There is an alternative, much simpler way of looking at it that dates back to an overlooked 1996 paper by Nicolas Cerf and Christof Adami: the arrow of time depends on entanglement because that's the only way to get classical correlations (i.e. memories) out of quantum mechanics.<p><a href="https://blog.rongarret.info/2014/09/are-parallel-universes-real.html" rel="nofollow noreferrer">https://blog.rongarret.info/2014/09/are-parallel-universes-r...</a><p><a href="https://blog.rongarret.info/2014/10/parallel-universes-and-arrow-of-time.html" rel="nofollow noreferrer">https://blog.rongarret.info/2014/10/parallel-universes-and-a...</a><p>You can arrive at the same conclusion relying solely on the theory of decoherence, which can be traced back as early as 1970:<p><a href="https://ui.adsabs.harvard.edu/abs/1970FoPh....1...69Z" rel="nofollow noreferrer">https://ui.adsabs.harvard.edu/abs/1970FoPh....1...69Z</a>