<Li> The broad consensus among the scientific community today is that smooth initial conditions lead to a highly non-smooth final state, and that this is in fact the source of the thermodynamic arrow of time . Highly non-smooth gravitational systems tend to collapse to black holes, so the wavefunction of the whole universe evolves from a superposition of small fluctuations to a superposition of states with many black holes in each . It may even be that it is impossible for the universe to have both a smooth beginning and a smooth ending . Note that in this scenario the energy density of the universe in the final stages of its shrinkage is much larger than in the corresponding initial stages of its expansion (there is no destructive interference, unlike in the first scenario described above), and consists of mostly black holes rather than free particles . </Li> <P> In the first scenario, the cosmological arrow of time is the reason for both the thermodynamic arrow of time and the quantum arrow of time . Both will slowly disappear as the universe will come to a halt, and will later be reversed . </P> <P> In the second and third scenarios, it is the difference between the initial state and the final state of the universe that is responsible for the thermodynamic arrow of time . This is independent of the cosmological arrow of time . In the second scenario, the quantum arrow of time may be seen as the deep reason for this . </P>

How does the rule of closure affect perception