Could time really move both forward and backward? Discover how quantum physics is challenging what’s known about time now!
A compelling possibility has been revealed through recent scientific investigation: time, at the quantum scale, may not follow a strictly forward direction. Although everyday perception reinforces the notion of time as irreversible, deeper insights from fundamental physics challenge this assumption.
Research conducted on open quantum systems, even when accounting for energy dissipation into the surrounding environment, indicates that the symmetry of time remains unbroken. A notable mathematical element known as the “memory kernel” emerged in the findings, offering support to the idea that time might, in theory, progress both forward and backward. Such revelations have the potential to transform the prevailing understanding of time, the nature of physics, and the structure of the universe.
A reconsideration of time has been proposed: could it be that time flows not only forward but also in reverse under certain quantum conditions? This possibility has been explored by researchers at the University of Surrey, where it was revealed that opposing directions of time may theoretically arise within specific quantum systems.
For generations, the concept known as the arrow of time — the belief in an irreversible forward flow — has shaped scientific thought. While this notion aligns with daily experience, the foundational principles of physics remain neutral. The governing equations of motion exhibit no preference, functioning identically whether time progresses or rewinds.
The Milk & The Pendulum
As explained by Dr. Andrea Rocco, Associate Professor in Physics and Mathematical Biology at the University of Surrey and lead author of the study:
“One way to explain this is when you look at a process like spilled milk spreading across a table, it’s clear that time is moving forward. But if you were to play that in reverse, like a movie, you’d immediately know something was wrong – it would be hard to believe milk could just gather back into a glass.
“However, there are processes, such as the motion of a pendulum, that look just as believable in reverse. The puzzle is that, at the most fundamental level, the laws of physics resemble the pendulum; they do not account for irreversible processes. Our findings suggest that while our common experience tells us that time only moves one way, we are just unaware that the opposite direction would have been equally possible.”
Such insights invite a broader reflection on the nature of time and perception, especially within systems where balance and rhythm — familiar in health and wellness practices — play a central role.
A recent study featured in Scientific Reports delved into the reversibility of time within quantum systems — the realm of sub-atomic particles. Focus was placed on the behavior of an “open quantum system,” where interaction with a surrounding environment plays a central role. The investigation aimed to uncover whether the perception of time’s forward flow arises from such interactions.
To streamline the exploration, two foundational assumptions were applied. First, the vast surrounding environment was modeled in a way that allowed exclusive attention on the quantum system itself. Second, the environment — comparable in scale to the entire universe — was considered so immense that any dissipated energy or information would not return. These conditions created an ideal framework to analyze how a directional flow of time may emerge, despite the underlying physics allowing for symmetry in both directions.
Such concepts resonate with those who value the subtle connections between science and natural order, where unseen forces and balance shape both the body and the universe.
The direction of time, long assumed to be fixed, may not hold such certainty at the quantum level.
Even after standard assumptions were applied, the behavior of the system remained unchanged regardless of whether time moved forward or in reverse. This result offers a strong mathematical basis for the presence of time-reversal symmetry in open quantum systems, challenging the familiar sense of a one-way temporal flow.
As described by Thomas Guff, postdoctoral researcher and lead on the calculations:
“The surprising part of this project was that even after making the standard simplifying assumption to our equations describing open quantum systems, the equations still behaved the same way whether the system was moving forwards or backward in time. When we carefully worked through the maths, we found that this behavior had to be the case because a key part of the equation, the ‘memory kernel,’ is symmetrical in time.
“We also found a small but important detail which is usually overlooked – a time discontinuous factor emerged that keeps the time-symmetry property intact. It’s unusual to see such a mathematical mechanism in a physics equation because it’s not continuous, and it was very surprising to see it pop up so naturally.”
These findings open the door to rethinking rhythms and cycles beyond the visible — a perspective often embraced in holistic health, where balance and flow are viewed as essential to both well-being and the nature of existence itself.
https://www.nature.com/articles/s41598-025-87323-x
Summary
Deriving an arrow of time from time-reversal symmetric microscopic dynamics is a fundamental open problem in many areas of physics, ranging from cosmology, to particle physics, to thermodynamics and statistical mechanics. Here we focus on the derivation of the arrow of time in open quantum systems and study precisely how time-reversal symmetry is broken. This derivation involves the Markov approximation applied to a system interacting with an infinite heat bath. We find that the Markov approximation does not imply a violation of time-reversal symmetry. Our results show instead that the time-reversal symmetry is maintained in the derived equations of motion. This imposes a time-symmetric formulation of quantum Brownian motion, Lindblad and Pauli master equations, which hence describe thermalisation that may occur into two opposing time directions. As a consequence, we argue that these dynamics are better described by a time-symmetric definition of Markovianity. Our results may reflect on the formulations of the arrow of time in thermodynamics, cosmology, and quantum mechanics.