Figuring out the universe for all of us


November 13, 2005

When it comes to pondering fundamental questions about the nature of the universe, three scientists working at the Johns Hopkins University are among the leaders of the pack.

It's a challenging race to be in these days, attempting to answer cosmic questions like the nature of the weak gravitational force that permeates the universe, or the "dark energy" that seems to be pushing the universe apart.


"My research looks back to the dawn of time and the very earliest moments of the universe, where our two models of physics - gravity physics and quantum mechanics - break down and conflict with each other," said astrophysicist Charles Bennett. "It also looks to the end of the universe, to the very far future and its ultimate fate."

This year Bennett was elected to membership in the National Academy of Sciences, one of the highest honors for an American scientist or engineer.

Bennett also was awarded the Henry Draper Medal at the academy's meeting. The medal is awarded every four years to an honoree who has made significant contributions to astronomical physics.

Bennett's insights into the origins and fate of the universe come from precise study of a form of radiation that permeates the universe. Located in the microwave portion of the electromagnetic spectrum, this radiation is an "echo" of the big bang, the explosive moment of the universe's creation.

Bennett has been a leading contributor to two of the most ambitious attempts to map very slight variations in this echo across the vastness of the universe. The maps help Bennett and other astrophysicists learn more about the earliest stages of the universe and the history of its development, revealing, for example, the precise age of the universe: 13.7 billion years.


Hopkins physics professor Raman Sundrum believes questions about the nature of our universe may be solved by understanding its relationships with a series of parallel universes in other dimensions that are influencing what happens here.

Sundrum thinks these extra dimensions are essential to putting together a Grand Unified Theory, a comprehensive scientific picture of the nature of matter, space, time and energy. Ideally, the theory would seamlessly explain space and time, how forces are conveyed across space, how matter is created from tiny particles smaller even than protons and electrons. It would unify all the great physics theories and models.

Testing Sundrum's ideals will require using particle colliders to smash particles together to produce showers of new and extremely short-lived particles. Tracking the motion of these tiny particles should offer clues to the properties of the extra dimensions that may shadow our universe.

"It's going to be a huge challenge," Sundrum said in a recent magazine interview.


Adam Riess, a Space Telescope Science Institute astronomer who recently accepted a professorship at Hopkins, was a leading member of a team of researchers that used spectroscopic observations of distant exploding stars to uncover a completely unexpected aspect of the development of the universe.

In 1998, Riess published the first evidence that the expansion of the universe was accelerating and was filled with dark energy, a result that was called the Breakthrough Discovery of the Year by Science Magazine that year.

"We think dark energy pervades the vacuum of space and pushes the universe apart so strongly that it overcomes the gravitational pull all the parts of the universe exert on each other," he recently explained. "Trying to understand what dark energy might be is one of the biggest mysteries in physics right now."

In 1999, Riess received the Robert J. Trumpler Award from the Astronomical Society of the Pacific for the doctoral thesis with the greatest impact in astrophysics. In 2000, Time Magazine named Riess one of 100 "Innovators of the Future" and one of six in the sciences.

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