Such alternative definitions of arrow of time are needed, for example, in cosmology to explain cosmological models like the oscillating universe. According to this model, the universe, which we know to be expanding, will reach a maximum size and then start contracting once again due to gravity. In such a contracting phase, entropy may actually decrease. If this happens, it will mean the arrow of time defined using entropy will reverse, and that sounds physically impossible
If you want to change selection, open document below and click on "Move attachment"

Unknown title
arge blobs to smaller blobs and then to still smaller blobs. In the same way, energy gets transferred from a large scale to the small scale, there by defining a direction for the arrow of time. <span>Such alternative definitions of arrow of time are needed, for example, in cosmology to explain cosmological models like the oscillating universe. According to this model, the universe, which we know to be expanding, will reach a maximum size and then start contracting once again due to gravity. In such a contracting phase, entropy may actually decrease. If this happens, it will mean the arrow of time defined using entropy will reverse, and that sounds physically impossible. Oscillating universe “The second law of thermodynamics encounters difficulties in explaining cosmological arrow of time for oscillating universe. However, energy transfers can predict