Time may not just move forward, experts think it may also rewind

Time usually moves from yesterday to tomorrow in a straight line. Many people accept this without question, but some scientists suspect our sense of forward progression could be missing an entire other direction.

Evidence now suggests that time may operate in both directions at once, though we remain oblivious to the backward flow.

The research was led by Dr. Andrea Rocco, an associate professor of physics and mathematical biology at the University of Surrey.

Does time really only move forward?

“One way to explain this is when you look at a process like spilt 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,” said Dr. Rocco.

He points out that certain physical laws appear neutral about the direction of time, yet our everyday world does not reflect that neutrality. This divide sparks curiosity about whether forward-only time is just a convenient interpretation.

Quantum physics suggests time may reverse

In the quantum domain, tiny particles can show bizarre behavior that seems unnatural on larger scales.

When these particles interact with an environment, they form a type of open quantum system that can leak energy or information in subtle ways.

Scientists suspected that once those details escaped into a huge environment, there was no coming back, reinforcing the idea of a one-way timeline. The new study challenges this belief by suggesting that the fundamental equations allow for a hidden reverse route as well.

The surprise factor

Mathematical models revealed an unexpected consistency in the equations when time was flipped. The researchers noticed that certain adjustments, normally used to simplify the math, did not break the possibility of reverse flow at all.

“The surprising part was that even after simplifying our equations, they behaved the same whether moving forward or backward in time. This had to be the case because the ‘memory kernel’ is symmetrical,” said Dr. Thomas Guff, who led the calculations.

Loophole allows time to move backward

One detail often overlooked is the time-discontinuous factor, which preserves an odd balance in the equations.

While everyday experience pushes us to assume time can only move forward, the time-discontinuous factor keeps the backward path mathematically valid.

In practice, this means a system could, in theory, follow a trajectory that looks normal in reverse. At larger scales, we rarely see this because chaos and complexity hide such reversals from casual observation.

Two directions are possible

According to the experts, the second law of thermodynamics still holds even when two directions are possible.

Entropy, which measures disorder, grows from whichever point we label as the start, so each direction still looks irreversible from its own vantage point.

In other words, you cannot spontaneously return spilled milk to the glass if you view that event as your baseline. The laws do not demand a single universal arrow; they only state that disorder tends to go up from any chosen beginning.

Time moving forward and backward

Some believe that if the universe had a clear initial condition, it might have sprouted two directions of time at once. We follow one arrow, but there could be another evolving away from the same cosmic starting point.

This idea may seem bold, but it raises fundamental questions about why time appears to move in only one direction in our everyday experiences.

In the physical world, we observe events unfolding in a forward sequence – water spills but does not unspill, people age rather than grow younger, and past events remain fixed while the future remains uncertain.

However, some scientific theories suggest that this forward movement may not be an inherent feature of time itself but rather a product of how we perceive and interact with the universe.

By studying hidden symmetries in quantum systems, researchers are investigating whether time has an underlying balance, allowing it to move both forward and backward under certain conditions.

These studies aim to determine whether time’s apparent one-way flow is simply a limitation of our human experience or a more profound law of nature.

The study is published in Scientific Reports.

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