Researchers observe predicted quantum gravity phase
Jerusalem (ANTARA) - An international team of researchers has observed long-predicted gravitational effects on falling quantum objects, demonstrating that the key principles behind Einstein’s theory of gravity remain valid even in the quantum world, according to a statement from Ben-Gurion University of the Negev, Israel, on Thursday.
Einstein’s equivalence principle is the idea that gravity affects all objects equally, regardless of their mass. According to this principle, a free-falling observer should experience no local gravitational force.
However, quantum objects can behave as waves and effectively move along more than one path, raising questions as to whether this principle remains valid when an ‘object’ does not follow a single, definite classical path.
In a new study published in the journal Science Advances, researchers tested this principle on microscopic objects governed by quantum mechanics. They found that gravity behaves exactly as Einstein predicted.
The team used atoms cooled to extremely low temperatures and placed in a quantum state that allowed the atoms to follow two paths simultaneously.
They utilised the Quantum Galileo Interferometer, named in honour of Galileo’s work on gravity. The device allowed them to split the quantum wave associated with an atom into two paths—one path in a stationary position (relative to the laboratory and Earth) and another in a state of free fall—and then recombine the two paths to observe how gravity alters the wave on the falling path.
When the two paths were recombined, the researchers observed a small change in the quantum state of the atom, and the results were identical to those predicted when Einstein’s principle was applied to the quantum wave.
The researchers stated that their experiment provides insight into one of the most fundamental questions in physics: how gravity, described by Einstein’s theory of relativity and quantum theory, can be unified into a single understanding of the universe.
The researchers noted that their findings do not prove that gravity itself is quantum, but demonstrate that under these testing conditions, Einstein’s equivalence principle remains valid alongside quantum mechanics.
They added that their technique could enable future experiments with heavier objects, such as nanodiamonds, to test whether quantum mechanics might cease to apply under extreme conditions.