The theories of quantum mechanics and gravity have been known to be incompatible, despite the efforts of dozens of physicists in the last fifty years. Recently, however, an international team of researchers led by physicists at the University of Vienna, the Austrian Academy of Sciences, and the University of Queensland (AUS) and the Stevens Institute of Technology (USA) have combined key elements of the two theories to describe the flow of time and discover that the timeline between events may exhibit true quantum characteristics.
According to general relativity, the presence of a massive object slows down the passage of time. This means that a clock placed close to a massive object will run slower than an identical one, which is farther away.
However, the rules of quantum theory allow each object to be prepared in a state of superposition. A two-position superposition state is different from placing an object in one place or another on a random basis – it is another way of having an object permitted by the laws of quantum physics.
One of the open questions in physics is: What happens when an object massive enough to affect the passage of time is placed in a state of quantum superposition?
This is a controversial topic: some physicists argue that such scenarios are fundamentally impossible – some new mechanism must block the initial formation of superposition while others develop whole theories based on the assumption that this is possible.
"We began by solving the question: what would a clock measure if it were influenced by a massive object in a state of quantum superposition?" explains Magdalena Zich of the University of Queensland.
Scientists expected to face the obstacles that make the scenario impossible, but surprisingly, using standard textbook physics, they were able to describe exactly what was happening.
They found that when a massive object is placed in a quantum superposition near a set of clocks, their order can become truly quantum, refuting any classical description.
Kaslav Bruckner, a co-author at the University of Vienna and the Austrian Academy of Sciences, added that the regime under which a quantum time line could occur is far removed from our daily experience, "but the most important understanding of our work is that a quantum timeline is possible at all and that this leads to new physical effects. "
To illustrate what is going on, imagine a pair of star ships training for a mission. They are required to fire at each other at certain times and immediately start their engines to avoid their attack on each other. If one of the ships shoots too early, it will destroy the other and this establishes an unmistakable timeline between fire events.If a powerful agent could place a massive enough object, say a planet closer to one ship, it would slow down As a result, the ship that is
The laws of quantum physics and gravity predict that by manipulating the state of a quantum superposition on the planet, ships can be in superposition of any one Such a state of superposition involving two systems is called entangled.The new work shows that the temporal order of events may exhibit superposition and entanglement – true quantum characteristics of particular importance for testing quantum theory. th against the alternatives. The result can now be used as a theoretical field to test frames of quantum gravity and thus help to advance the formulation of the correct theory of quantum gravity.
The study will also be relevant for future quantum technologies. Quantum computers that use the quantum order of operations can defeat devices that only work in fixed sequences. The practical implementations of the quantum time series do not require extreme conditions – for example planets in superposition – and can be simulated without the use of gravity. Discovering the quantum properties of time can lead to better quantum devices in the coming era of quantum computers.
How Einstein's Equivalence Principle Extends to the Quantum World
Magdalen Zich et al. Bell's Temporal Order Theorem, Nature Communications (2019). DOI: 10.1038 / s41467-019-11579-x
University of Vienna
The Intricate Times of Quantum Gravity (2019, August 22)
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