Time may not be a fundamental element of the universe, but an illusion arising from quantum entanglement, a new study suggests.
time it is a thorny problem for physicists; Its inconsistent behavior among our best theories of the universe contributes to a deadlock that prevents researchers from finding a “theory of everything,” or a framework to explain all the physics in the universe.
But in the new study, researchers suggest they may have found a clue to solving this problem: making time a consequence of quantum entanglement, the strange connection between two distant particles. The team published their findings May 10 in the journal Physical review A.
“There is a way to introduce time that is consistent with classical laws and quantum laws, and is a manifestation of entanglement,” first author Alessandro Coppo, a physicist at Italy’s National Research Council, told Live Science. “The connection between the clock and the system creates the appearance of time, a fundamental ingredient in our lives.”
It’s a matter of time
IN Quantum mechanics, our best theory of the microscopic world, time is a fixed phenomenon—an inexorable, one-way flow from past to present. It remains external to the strange and ever-changing quantum systems it measures and can only be seen by observing changes in external entities, such as the hands of a clock.
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However, according to Einstein’s theory of general relativity – describing larger objects, such as our bodies, stars and galaxies – time is intertwined with space and can be warped and expanded at high speeds or in the presence of gravity. This leaves our two best theories of reality at a fundamental impasse. Without its solution, a coherent theory of everything remains unattainable.
“There seems to be a serious inconsistency in quantum theory,” Coppo said. “This is what we call the problem of time.”
To solve this problem, the researchers turned to a theory called the Page and Wootters mechanism. First proposed in 1983, the theory suggests that time passes for an object through it quantum entanglement with another acting as a clock. For an unentangled system, on the other hand, time does not exist and the system perceives the universe as frozen and unchanging.
By applying the Page and Wootters mechanism to two theoretically entangled but non-interacting quantum states—one a vibrating harmonic oscillator and the other an array of small magnets acting like a clock—the physicists found that their system could be perfectly described by the Schrödinger equation, which predicts the behavior of quantum objects. However, instead of time, their version of the famous equation was developed according to the states of small magnets that act as clocks.
This discovery is not new, but the team’s next step was. They repeated their calculations twice, assuming first that the magnetic clock and then the harmonic oscillator were macroscopic (larger) objects. Their equations simplified to those for classical physics, suggesting that the flow of time is a consequence of entanglement even for large-scale objects.
“We strongly believe that the correct and logical direction is to start from quantum physics and figure out how to get to classical physics, not the other way around,” Coppo said.
Other physicists have expressed caution. Although Page and Wootters found the mechanism a fascinating idea for the quantum origins of time, they said it has yet to produce anything testable.
“Yes, it is mathematically consistent to think of universal time as the interplay between quantum fields and quantum states of 3D space.” Vlatko Vedral, a professor of quantum information science at Oxford University who was not involved in the work, told Live Science. “However, no one knows whether anything new or fruitful will come out of this picture—such as modifications to quantum physics and general relativity, and corresponding experimental tests.”
Despite these misgivings, building basic theories of time from quantum mechanics may still be a promising place to start—as long as they can be shaped to fit experiments.
“Maybe there’s something about the mess that plays a part,” Adam Frank, a theoretical physicist at the University of Rochester in New York who was not involved in the study, told Live Science. “Perhaps the only way to understand time is not from a God’s-eye perspective, but from within, from a perspective of asking what life is that exhibits such a view of the world.”