A team of researchers from the University of Surrey has made a groundbreaking discovery that could change how we think about time. A new study shows that time might not be as fixed as we’ve always believed. Instead of always flowing from the past to the future, time could theoretically flow in both directions, depending on processes happening at the quantum level. This study, published in Scientific Reports, could have significant implications for understanding how time works in the universe.

The idea that time flows in one direction—referred to as the “arrow of time”—has puzzled scientists for centuries. We experience time moving forward, but the laws of physics don’t favor this direction. Whether time moves forward or backward, the equations that describe it remain the same. In everyday life, it’s easy to recognize that time moves forward, like when spilled milk spreads across a table. But scientists have long wondered if time could also move backward, even though we don’t see this happening in our daily experiences.

In their study, the researchers focused on “open quantum systems,” which study how very small, sub-atomic particles interact with their environment. They wanted to understand why we perceive time as always moving forward, even though, at the microscopic level, it could move in both directions. The team used mathematical models and made two key assumptions to do this. First, they focused on the quantum system, ignoring the larger environment. Second, they assumed that energy and information from the system would dissipate into the environment, never returning.

The surprising result from the team’s calculations was that time could theoretically move forward and backward in specific quantum systems. This discovery challenges the traditional view that time always moves in one direction. The study suggests that time’s arrow, or how we experience time, might not be as fixed as we think. This could change how scientists approach time in fields like quantum mechanics, cosmology, and thermodynamics, offering new insights into one of the biggest mysteries in physics.

References

• University of Surrey. (2025, February 13). Physicists uncover evidence of two arrows of time emerging from the quantum realm. Phys.Org; University of Surrey. https://phys.org/news/2025-02-physicists-uncover-evidence-arrows-emerging.html
• Guff, T., Shastry, C. U., & Rocco, A. (2025). Emergence of opposing arrows of time in open quantum systems. Scientific Reports, 15(1), 3658. https://doi.org/10.1038/s41598-025-87323-x