Quantum Physics: Time's Arrow Remains a Mystery Despite New Study

A team at the University of Surrey, including Andrea Rocco, has challenged existing theories about time's directionality at the quantum level. Classical physics dictates time moves forward due to the second law of thermodynamics, increasing disorder (entropy). However, fundamental equations in physics, like Newton's and Schrodinger's, are time-reversal invariant, suggesting no preferred time direction. This creates a conflict: how does time gain a direction when the underlying equations are symmetrical? Researchers examined a quantum object in an infinite thermal bath, expecting to see energy dissipation that would indicate a time direction. However, their rigorous analysis revealed the equations remain time-reversal invariant. The system equilibrates whether moving forward or backward in time, dissipating energy in both directions. This suggests the system 'chooses' a timeline, aligning with the second law of thermodynamics, but the reason for this selection remains unknown. The findings suggest the coexistence of opposing time arrows is a general phenomenon, applicable to other systems, deepening the mystery of time's arrow in quantum mechanics.