Physicists are one step closer to the measurement of gravity at the quantum level, according to a team whose recent studies move us closer to understanding some of the most mysterious forces at work in our universe.
Gravity is the fundamental interaction that produces attraction between all the objects possessing mass in our universe. Although the weakest of the four fundamental interactions recognized by physicists, it is the one that most of us are familiar with, as we experience the effects of gravity virtually every moment of our lives.
However, due to its weakness, gravity has no significant influence when it comes to subatomic particles, and experts have long questioned how it works in the quantum realm—a conundrum that even baffled Albert Einstein, whose theory of general relativity argued that there are no experiments that could demonstrate a quantum version of gravity.
That is until now, as an international team of physicists says they have succeeded in developing a novel technique that allowed them to detect a weak gravitational pull on a microscopic particle, an achievement which they say may advance our progress toward unraveling a long-sought theory of quantum gravity.
In their experiment, the physicists were able to detect gravity on tiny particles near the boundaries of the quantum realm by employing superconducting devices called traps. During their experiment, they measured a weak pull from a microscopic particle by levitating it under extreme freezing conditions approaching absolute zero.
University of Southampton physicist Tim Fuchs said the achievement could help move us toward understanding our universe by revealing a missing puzzle piece in our current picture of reality.
“For a century, scientists have tried and failed to understand how gravity and quantum mechanics work together,” Fuchs said in a statement.
“Now we have successfully measured gravitational signals at [the] smallest mass ever recorded, it means we are one step closer to finally realizing how it works in tandem,” he added.
Fuchs said that his team’s next objective is to attempt to reduce the scale of the source using the new technique so that it can be applied to the quantum world on both sides. This could help scientists to unravel some of the most pressing mysteries about our universe, including its origins, and whether there is indeed a grand theory that unites all the known forces.
Presently, quantum phenomena are still mysterious to physicists like Fuchs, since the behavior of particles at the microscopic scale is vastly different from how matter behaves at the normal scale we experience in our daily lives.
However, the new findings could enable future experiments involving even smaller objects.
“Our new technique that uses extremely cold temperatures and devices to isolate vibration of the particle will likely prove the way forward for measuring quantum gravity,” said Hendrik Ulbricht, a Professor of Physics at the University of Southampton.
“Unravelling these mysteries will help us unlock more secrets about the universe’s very fabric, from the tiniest particles to the grandest cosmic structures.”
The team’s new study, “Measuring gravity with milligram levitated masses,” appeared in the February 23, 2024 edition of Science Advances.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.