Dark Energy 'Chameleon' May be Snared with New Experiment

First Posted: Aug 24, 2015 08:16 AM EDT

Dark energy may be hiding in our midst in the form of hypothetical particles called "chameleons." Now, one researcher has a plan to flush them out.

Dark energy was first discovered in 1998 when scientists saw that the universe was expanding at an ever increasing rate, apparently pushed apart by an unseen pressure permeating all of space and making up about 68 percent of the energy in the cosmos.

Since then, researchers have proposed several theories to explain dark energy. It could be simply woven into the fabric of the universe, or it could be quintessence, represented by any number of hypothetical particles, including offspring of the Higgs boson.

In 2004, researchers proposed one possible reason why dark energy particles haven't been detected. It could be that they're "hiding" from us. Dark energy particles, dubbed chameleons, may vary in mass depending on the density of surrounding matter. In the emptiness of space, chameleons would have a small mass and exert force over long distances. In the lab, though, they would have a large mass and extremely small reach. This would be one reason why the energy that dominates the universe is hard to detect in a lab.

"The chameleon field is light in empty space but as soon as it enters an object it becomes very heavy and so couples only to the outermost layer of a big object, and not to the internal parts," said Holger Muller, one of the researchers, in a news release. "It would pull only on the outermost nanometer."

In this latest study, the researchers measured the attraction caused by the chameleon field between an atom and a larger mass rather than the attraction between two large masses. The researchers ruled out chameleons that interact with normal matter more strongly than gravity. In addition, the researchers are now pushing their experiment into areas where chameleons interact on the same scale as gravity, where they are more likely to exist.

The findings are published in the journal Science.

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TagsDark Matter, Dark Energy, Particle Physics, Particle Accelerator, Particle Detector, Subatomic Particles, Physics, space, Universe