Professor Justin Khoury: Experiment Attempts to Snare Penn Astrophysicist’s Dark Energy ‘Chameleons’

If dark energy is hiding in the form of hypothetical particles called “chameleons,” a team of researchers at the University of Pennsylvania and the University of California, Berkeley, plans to flush them out.

The results of an experiment published in Science narrows the search for chameleons a thousand times compared to previous tests. The researchers hope that their next experiment will either expose chameleons or similar ultralight particles as the real dark energy, or prove they were nothing more than an illusion.

The study was led by Holger Müller, an assistant professor of physics at Berkeley and a faculty scientist at Lawrence Berkeley National Laboratory; Berkeley post-doctoral fellow Paul Hamilton; and Justin Khoury, an associate professor in the Department of Physics and Astronomy in Penn’s School of Arts & Sciences.

To read the article in full, visit