Penn Physicist’s Dark Energy Project Awarded $1 Million From a W.M. Keck Foundation

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A partnership between University of Pennsylvania and University of California, Berkeley, that is exploring a category of dim appetite theories, called chameleon theories, has been awarded $1 million from a W.M. Keck Foundation.

​​​​​​​Justin Khoury, a highbrow in a Department of Physics Astronomy in a School of Arts Sciences during Penn, primarily grown a plan in 2004, while a postdoc during Columbia University.

If chameleons exist, cesium atoms would tumble toward a globe with a somewhat incomparable acceleration than sobriety predicts.

Dark appetite was initial detected in 1998 when scientists celebrated that a star was expanding during an ever-increasing rate, apparently pushed detached by an secret vigour permeating all of space and creation adult about 68 percent of a appetite in a cosmos.

“Dark appetite is one of a many dire puzzles in physics,” Khoury said. “It creates adult many of a universe, so we unequivocally ought to know what’s going on. Most likely, an bargain of dim appetite is going to tell us something surpassing about production and scholarship some-more generally.”

There are many proposals about a inlet of dim energy. The simplest one, Khoury said, is that dim appetite is only a appetite of a opening of space, that would have no laboratory or solar complement implications. This opening appetite would be consistent in space and time, doing zero other than conversion a enlargement of a universe.

“If that’s how dim appetite is, afterwards we have no possibility of detecting it locally,” Khoury said.

What distinguishes theories like a chameleon is that they indeed make predictions for experiments on Earth. In these theories, dim appetite is noticed as dynamic: it evolves in time and varies in space.

The opening cover of a atom interferometer contains a one-inch hole aluminum sphere. Image credit: Holger Muller

“Chameleons are fundamentally a form of dim appetite whereby a representative that gives arise to dim appetite can change a properties depending on a environment,” Khoury said. “In sold it uses a vast firmness of a internal sourroundings to censor itself from experiments. If we have vast objects such as Earth or a sun, a effects of a chameleon will be well hidden. But if we take a tiny particle, such as an atom, it can have a comparatively estimable effect.”

At Berkeley, researchers concerned in a collaboration, led by Holger Müller, an associate highbrow of production and a element questioner of a project, use a technique called atom interferometry to examine these ideas. Atom interferometry harnesses a elemental element of quantum mechanics called superposition, that states that particles can be in dual places during a same time.

The researchers start with a source globe in a opening chamber. They recover a cloud of atoms, that they can control with lasers. They initial separate a atoms’ call functions so that they go by dual opposite paths during once, and afterwards they recombine a atoms, measuring a force between a source mass and a atoms. The whole experiment, Khoury said, fits on a tabletop.

“The suit of these atoms are governed by gravity,” he said. “But if there were a chameleon force, afterwards that would also change their motion. By regulating atom interferometry, they can indeed tell possibly or not there’s a chameleon force on tip of gravity. It’s a unequivocally powerful, intensely accurate experiment. It’s also cutting-edge. This margin of atom interferometry is comparatively new, and it’s a really prohibited field, and so this partnership is bringing Berkeley’s imagination to try to constrain or potentially learn this speculation of dim energy.”

The W. M. Keck Foundation Science and Engineering Grant will support both a initial work during Berkeley and a fanciful work finished during Penn. Atom interferometry frequency interplays with cosmology, Khoury said, though it is a burgeoning area or investigate that he hopes will turn mainstream somewhere down a road. The extend will concede a partnership to pull things brazen in a large way.

“What’s really cold to me,” Khoury said, “is that we’re regulating tabletop experiments, that routinely you’d consider would have no approach import for how we know dim appetite and a enlargement of a star since that’s something that’s function on most incomparable scales. When we initial came adult with chameleons, we never dreamed that somebody one day would be regulating this cutting-edge examination in a laboratory to possibly constrain or maybe order out this kind of idea.”

Source: University of Pennsylvania

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