Time May Emerge As The Result of Quantum Entanglement

Time has always been an essential element of our universe but new research suggests it might just be an illusion caused by quantum entanglement

Hiya!

One of the coolest things about being alive today is the many scientific discoveries occurring thanks to advancing technology. Artificial intelligence and supercomputers empower scientists to test the never-ending flow of new theories and revisit older theories that arose before the technology existed to test them.

Like today’s topic — Time. It almost seems silly to question time, as it’s generally considered a fundamental element of our physical reality and possibly the fourth dimension. Yet, recent studies suggest time isn’t as fundamental as we think. In fact, new research proposes that time is an emergent property of quantum physics.

How to Measure Time

Physics Researcher Alessandro Coppo at the National Research Council of Italy and leader of new research I’ll tell you about soon told Karmela Padavic-Callaghan of New Scientist that,

“For centuries, time has entered physics as an essential ingredient that is not to be questioned. It is so deeply rooted in our conception of reality that people thought that a definition of time was not needed.”

That is until the 1900s when classical and quantum physics introduced conflicting views regarding time.

In classical physics, which describes the physical world we can see, Albert Einstein introduced his theory of special relativity (which the infamous E=mc2 comes from) in 1905. This theory combines space and time into a unified fabric called spacetime, where our physical reality exists. A decade later, in 1915, Einstein expanded special relativity to account for gravity in his theory of general relativity, which says gravity can dilate and warp time.

Meanwhile, time has a different role in quantum physics, which describes the microscopic, or quantum, world. Quantum theory says time is static and doesn’t change like other properties of a quantum object. Any changes in time require an observer to consult an external clock that can measure changes in another object.

The theories’ incompatible views of time are just one of many conflicts between them. Yet, even though general relativity describes large objects and quantum theory describes the microscopic, all objects, regardless of size, exist in the same universe, so many scientists believe time should be consistent across the spectrum.

Coppo, in collaboration with Professor A. Cuccoli from the University of Florence and colleagues, searched for a way to unite the opposing views of time — and they may have found one involving an abstract and little-known theory.

The Page and Wootters Approach

The Page and Wootters approach is a bit tricky to grasp, but I’ll try my best to break it down. At its core is the idea that time is not fundamental but a consequence of entanglement.

The idea was generated by (and named after) theorists Don Page and William Wootters, who suggested in 1983 that the quantum phenomenon of entanglement can be used to measure time. Quantum entanglement describes the relationship between two quantum particles in which they share the same existence — what happens to one happens to the other instantaneously, regardless of distance.

Page and Wootters thought that the evolution of a pair of entangled particles is a type of clock that can be used to measure change. To clarify, “clock” in this sense isn’t like the one on our wrist, phone, or wall. The clock in Page and Wootter’s context can be anything with a predictable and uniform behavior that can be measured. For example, Earth’s rotation around the sun is a clock for our days and nights. But everything depends on the context of the observation.

When comparing the changes in entangled particles with an external clock, one that’s entirely independent of the universe (such as a god-like perspective from above), Page and Wootters found that time wouldn’t exist. Everything would be static and unchanging.

On the other hand, when the observer and the clock they use are inside the universe and can compare a particle’s evolution to the particles in the rest of the universe, the observer sees changes occur — and that is an important measure of time.

In other words, Page and Wootters wondered whether our sense of time results from the world being highly entangled with itself. They even suggested that humans are included in the entanglement just by witnessing the passage of time — because if we were outside the entangled system, we wouldn’t see time pass at all.

New Research

No wonder the Page and Wootters Approach has remained in the shadows for two decades — it’s challenging to comprehend. Yet, remarkably, Coppo and his team found a way to bring this immaterial concept into our material world with measurements based on real-life observation.

Coppo and his colleagues thought the Page and Wootters Approach could be a good place to begin looking for a common thread for time between general relativity and quantum theory. To turn time into something measurable, they restricted well-known physics equations to match Page and Wootters’ approach. They published their research in the American Physical Society’s peer-reviewed journal Physical Review A.

The team created several mathematical tests inspired by Page and Wootters using a system of tiny theoretical magnets to represent the clock. The magnets are entangled using a quantum oscillator, which is kinda like a quantum version of a spring. The researchers chose this route because these models are mathematically well understood, so they’re a good starting point and set the groundwork for future experiments.

Their system is similar to the Schrödinger equation, which predicts the behaviors of quantum particles — except instead of using time as the variable, the researchers used one representing the quantum state of the magnets.

The researchers thought time might be a consequence of entanglement, even when the objects are classical rather than quantum. So, they repeated the calculation but made the magnets and the oscillator large enough that quantum effects didn’t alter their behavior.

(Side note: when enough particles get together, they reach a threshold called “macroscopic,” which can be seen by the eye and were thought not to be affected by quantum effects — though that’s debatable now.)

Anyway, it turns out they were right. Their equations matched the ones physicists have used since the 19th century to predict the behavior of classical objects, like the pass of a ball during a game of catch.

What Does This Mean?

So why does any of this brain-bending gibber-jabber matter? In short, Coppo and his team’s research is a big step on the long road of uniting quantum mechanics and general relativity. Or, in the words of Basil Altaie at the University of Leeds in the UK told to Padavic-Callaghan:

“They are bridging quantum and classical time.”

Coppo and his team used a concrete and specific system to discover a variable that matched conventional time. Altaie said this could mean that the only way we should think about time is as arising from quantumness. Coppo told Padavic-Callaghan that,

“We believe that nature is genuinely quantum.”

The researcher’s solution might work for both classical and quantum mechanics, which is a huge deal. Caroline Delbert of Popular Mechanics summarizes the importance nicely:

“If our entire, very macroscopic world fits into this definition of time based on entanglement, it means everything around us is entangled. Things would need to be entangled almost by definition in order to be part of our observable world. And it would mean that anything we see where time passes (no matter how far away it is) is linked with us in a vital way.”

What’s Next?

As promising as Coppo’s research is, more research is definitely needed — the challenge is to develop more ways to test these ideas. For one thing, Coppo’s research assumes that two entangled systems don’t interact, but that might not always be true or true at all. So scientists need to continue finding ways to investigate time and figure out what it is using experimentation.

Vlatko Vedral, a Professor of Quantum Information Science at the University of Oxford, told Padavic-Callaghan that the clock and any other object might have to interact to become entangled. Understanding what happens to the type of time that emerges from such an interaction might be crucial for forming future testable theories of quantum gravity.

Perspective Shift

I wrote a while back about a new theory proposed by Chris Watson, an oncologist by day and physics enthusiast by night, which suggests gravity emerges due to entropy. I won’t get into the details here, but if he’s right, and these researchers are right that time emerges from quantum entanglement, then perhaps it’s time to review everything we thought we knew.

Physics isn’t the only subject in need of review. Most topics I write about seem to challenge the concept of reality we’ve all grown to accept. We’ve lived for so long thinking we have most everything figured out — or figured out enough — but we’re quickly realizing that we have no idea how much we don’t know. Still, it’s awfully exciting to see what we learn next.

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