The Gravitational Arrow of Time

Tim A. Koslowski (Brunswick) gives a talk at the Workshop on the Problem of Time in Perspective (3-4 July, 2015) titled "The Gravitational Arrow of Time". Abstract: The arrow of time appears to always to point in one direction (i.e. we can clearly tell whether a movie is played forward or backward) although the underlying physics is time-reversal symmetric. The most widely accepted explanation for this is that the experienced arrow is the thermodynamic arrow of time (i.e. the direction of entropy growth). This scenario requires the past hypothesis, i.e. an atypical initial condition. We propose an alternative mechanism: The arrow of time is the direction in which the complexity of the universe grows. Gravity generates this arrow of time and creates subsystems with low entropy initial conditions spontaneously. I show this in detail in the Newtonian limit and discuss the extension to cosmological models in GR.