As the question states, Why thermodynamic arrow of time will not reverse during the big crunch (considering our universe is above the critical mass)? The doubt arised because I thought the cosmological arrow of time is linked to the thermodynamical arrow of time I know that according to CPT symmetry, in any case the laws of physics, in this case 2nd law of thermodynamics shan't be reversed and must abide therefore time (since psychological time is linked to thermodynamical time) shall not be reversed But due to what mechanism this happens? Note: This would be considering our universe has sufficient mass-cosmological constant proportion that big crunch could occur, now maybe this is linked to the anthropotic principle and because of this the mass distribution is so finetuned, but maybe according to superposition this could occur in someone else's universe without changing the CPT symmetry or physical laws