Lab-based dark energy experiment narrows search options for elusive force

An experiment to test a popular theory of dark energy has found no evidence of new forces, placing strong constraints on related theories.


Scientists at Imperial College London and the University of Nottingham have tested the possibility that the dark energy is acting on single atoms, and found no evidence for it in their most recent experiment.

This could rule out well-known speculations of dark energy that alter the hypothesis of gravity and leaves fewer places to scan for the elusive fifth force.

Professor Ed Copeland, from the Centre for Astronomy & Particle Physics at the University of Nottingham, said: “This experiment, connecting atomic physics and cosmology, has allowed us to rule out a wide class of models that have been proposed to explain the nature of dark energy, and will enable us to constrain many more dark energy models.”

During experiments, scientists tried hypotheses of dark energy that propose the fifth power is relatively more fragile when there is more matter around – something contrary to how gravity acts.

This would mean it is solid in a vacuum-like space, however, is powerless when there is lots of matter around. Subsequently, tests utilizing two huge loads would mean the power turns out to be too weak to even think about measuring.

Scientists instead tested a larger weight with an incredibly small weight – a single atom – where the force ought to have been watched on the off chance that it exists. They used an atom interferometer to test whether there were any extra forces that could be the fifth force acting on an atom. A marble-sized sphere of metal was placed in a vacuum chamber and atoms were allowed to free-fall inside the chamber.

The hypothesis is, if there is a fifth force acting between the sphere and atom, the atom’s way will go astray somewhat as it goes by the sphere, causing an adjustment in the way of the falling atom. Be that as it may, no such power was found.

Professor Ed Hinds, from the Department of Physics at Imperial, said: “It is very exciting to be able to discover something about the evolution of the universe using a table-top experiment in a London basement.”

The study is published in the journal Physical Review Letters.

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