There are two conceptually different arrow of time problems. 1) observed, macroscopic arrow of time 2) microscopic, fundamental particle physics level arrow o

There are two conceptually different arrow of time problems. 1) observed, macroscopic arrow of time 2) microscopic, fundamental particle physics level arrow of time. Thermodynamic solution is satisfactory solution only for macroscopic arrow of time. Time reversal in general is not symmetric. There are particles that are violate CP and T-symmetry called kaons. That's completely different arrow of time.