An experiment to test a popular theory of dark energy has found no evidence of new forces, severely limiting related theories.
Dark energy is the name of an unknown force that causes an accelerated expansion of the universe.
Some physicists claim the dark energy is a & # 39; fifth & # 39; Force acting on matter beyond the four already known ̵
] However, researchers believe that this fifth force can be "scanned" or "hidden" on large objects such as planets or weights on Earth, making discovery difficult.
Now researchers at Imperial College London and the University of Nottingham have tested the possibility that this fifth force is acting on single atoms and has found no evidence in their most recent experiment.
This could preclude popular dark energy theories that modify the gravitational theory The experiment, conducted at Imperial College London and analyzed by theorists of the University of Nottingham, is reported in Physical Review Letters .
Professor Ed Copeland of the Center for Astronomy and Particle Physics at the University of Nottingham said: "This experiment, which combines atomic physics and cosmology, has enabled us to exclude a large class of models that have been proposed to explore the nature of dark energy to explain and allow us to restrict many more dark energy models. "
The experiment tested theories of dark energy that propose the fifth force is comparatively weaker there is more matter – the opposite of how gravity behaves.
This would mean that it is strong in a vacuum, but weak when there is a lot of matter in the vicinity. Experiments with two large weights would therefore mean that the force becomes too weak to be measured.
Experimenting With a Single Atom
The researchers instead tested a larger weight with an incredibly light weight – a single atom – where the force should have been observed when they did exist.
The team used an atomic interferometer to test for additional forces that could be the fifth force acting on an atom. A marble-sized metal ball was placed in a vacuum chamber and atoms could fall freely into the chamber.
The theory states that the path of the atom deviates when a fifth force between sphere and atom easily acts as it passes the sphere, thereby changing the path of the falling atom. However, no such force was found.
Professor Ed Hinds of the Institute of Physics in Imperial said: "It is very exciting to find out about the evolution of the universe in a table experiment.
Reference: "Experiment for detecting dark energy forces by atomic interferometry" by DO Sabulsky, I. Dutta, EA Hinds, B. Elder, C. Burrage and Edmund J. Copeland, August 6, 2019, Physical Review Letters . DOI: 10.1103 / PhysRevLett.123.061102