Is gravity a quantity? A new experience to explore the depths of the universe

• Scientists are developing an experiment to test whether gravity is quantum or not
• In quantum mechanics, which describes the behavior of atoms and molecules, things behave differently from everything we know: they can be in a state of quantum superposition such that they are in two places at the same time.
• Now, scientists are looking for a way to determine whether gravity works this way, by levitating tiny diamonds into a vacuum
• If gravity were quantum, diamonds would be “entangled” – an interesting phenomenon that strongly connects two objects in ways that are impossible in everyday life
• This research will help understand black holes the great explosionAnd the universe

Quantum gravity experiment

Scientists are developing an experiment to test whether gravity is quantum, one of the deepest questions about our universe.

General relativity and quantum mechanics are our two basic descriptions of nature. General relativity explains gravity on large scales while quantum mechanics explains the behavior of atoms and molecules.

The challenge of unifying theories

Arguably the most important unsolved problem in fundamental physics is the correct way to combine these two theories – to determine whether gravity operates at the quantum level. While theoretical work has suggested many possibilities, experiments are needed to fully understand the behavior of gravity.

A laser beam in Gavin Morley’s laboratory explores the quantum properties of diamonds. Credit: Gavin Morley

A revolutionary experience by the global consortium

For a hundred years, experiments on the quantum nature of gravity seemed far-fetched, but now scientists based at the Universities of Warwick, University College London, Yale (USA), Northwestern (USA), and Groningen (Netherlands) will work together to investigate this Puzzle. .

Their new idea is to lift two tiny diamonds into a vacuum and place them both in a quantum superposition of being in two places at the same time. This counterintuitive behavior is a fundamental feature of quantum mechanics.

Professor Morley’s vision of the experiment

Each diamond can be thought of as a smaller version of Schrödinger’s cat. Principal Investigator Professor Gavin Morley, Department of Physics, University of WarwickHe explains: “Schrödinger’s cat is a thought experiment that suggests that it would be really strange for everyday objects (and pets!) to be in a state of quantum superposition for being in two places at once. We want to test the limits of this idea.”

“We have successfully placed atoms and molecules in this state of superposition, but we want to do it with much larger objects. Our diamonds are made up of a billion or more atoms. To test the quantum nature of gravity, we must look for interactions between two of these diamonds due to gravity.”

“If gravity were quantum, it would be able to entangle two diamonds. Entanglement is a unique quantum effect where two things are connected more strongly than is possible in our everyday lives. For example, if two coins could be entangled, you might find that when you flip them, they come down In the same way even if it is impossible to know whether they will be both heads or tails.

Challenges and repercussions

There are still many challenges to realizing this idea, which the team will investigate during the project. “For example, we need to eliminate all interactions between nanoparticles other than gravity, which is very difficult because gravity is so weak,” says Dr. David Moore, from Yale University.

Professor Morley, who is the founding director of Warwick Quantum, a new multidisciplinary quantum technology research initiative, added: “For me, the most important problem in physics right now is developing an experiment that can test the quantum nature of gravity. This new project is an acceleration of our exciting journey towards just that.

Perspectives from collaborating scholars

Professor Sugato Bose, from University College London, commented: “It is difficult to overstate how important it is for physicists to conduct experiments that can discover the right way to combine quantum mechanics and general relativity. People working on theories of quantum gravity, such as string theory, usually focus on What happens at high energies, near black holes, and at the big bang.

“By contrast, our work is done in the low-energy regime here on Earth, but it will also provide invaluable information about… whether Gravity is quantum. The experiment can also be considered a verification of the general prediction of any quantum theory of gravity at low energies.

Professor Anupam Mazumdar, from the University of Groningen, adds: “On the way to understanding the quantum nature of gravity, we may be able to test other aspects of fundamental physics such as exotic deviations from Newtonian gravity over short distances.”

“This is a challenging experiment, and this project is groundbreaking in tackling some of the key technical challenges to making these tests of the quantum aspects of gravity a reality,” says Andrew Geraci, associate professor of physics. Northwestern University.

The project is called “MAST-QG: Macroscopic superpositions toward viewing the quantum nature of gravity.”