Justin Khoury Chases Astrophysicist’s Dark Energy ‘Chameleons’

A team of researchers at the University of Pennsylvania and the University of California, Berkeley, is investigating whether dark energy is in fact hiding in the form of hypothetical particles. The results of an experiment published in Science narrow the search a thousand times compared to previous tests. Representing Penn is Associate Professor of Physics and Astronomy Justin Khoury. The team hopes to expose the particles, dubbed “chameleons” by Khoury, or similar ultralight particles as the real dark energy, or prove they were nothing more than an illusion.

“One possible reason why dark energy particles haven’t been detected is that they’re hiding from us,” says Khoury, who in 2004 proposed that dark energy particles vary in mass depending on the density of surrounding matter.

Their experiments may also help narrow the search for other hypothetical screened dark energy fields, such as symmetrons, which were also proposed by Khoury with Penn postdoctoral researcher Kurt Hinterbichler in 2010, and forms of modified gravity, such as so-called f(R) gravity.

Click here to read the full article.