What if time is not as fixed as we thought? Imagine that instead of flowing in one direction—from past to future—time could flow forward or backwards due to processes taking place at the quantum level. This is the thought-provoking discovery made by researchers at the University of Surrey, as a new study reveals that opposing arrows of time can theoretically emerge from certain quantum systems.
For centuries, scientists have puzzled over the arrow of time—the idea that time flows irreversibly from past to future. While this seems obvious in our experienced reality, the underlying laws of physics do not inherently favor a single direction. Whether time moves forward or backwards, the equations remain the same.
Dr. Andrea Rocco, Associate Professor in Physics and Mathematical Biology at the University of Surrey and lead author of the study, said, "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."
The study, published in Scientific Reports, explored how a quantum system—the world of the sub-atomic—interacts with its environment, known as an "open quantum system."
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