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IU Media Relations

Edward Stephenson
IU Cyclotron Facility

Last modified: Thursday, December 18, 2003

IU physics discovery one of Discover magazine's top 100 stories of the year

The January 2004 issue of Discover magazine lists the top 100 science stories of 2003 ( Number 49 on the list is Indiana University physicist Edward Stephenson's experimental discovery of a rare fusion process that scientists had been trying to find since the 1950s (

Stephenson's results will help theorists understand the cause of charge symmetry violation, which underlies the differences between neutrons and protons and therefore makes possible the universe as we know it, including ourselves. Theorists have proposed that charge symmetry violation originates with quarks, the small particles that are found inside protons and neutrons.

"If this symmetry violation had happened to be in the other direction," Stephenson said, "hydrogen would not have survived after the Big Bang, and the universe would not have the hydrogen fuel that keeps stars shining, including our sun, making human life possible. Sometimes large consequences hang on delicate balances in nature."

The Discover article quotes Stephenson as follows: "There was a point about one second after the Big Bang when neutrons and protons condensed out of the underlying mixture of particles. The neutrons decayed into protons, but the protons remained stable. After 10 or 20 minutes, there was an enormous amount of the subatomic materials needed to form hydrogen, which is the building block of stars and galaxies. It is all a consequence of charge symmetry breaking down."

He and his colleagues did their experiment at the IU Cyclotron Facility on the Bloomington campus, focusing a high-precision beam of heavy hydrogen onto a target of the same material. The team worked around the clock for two months, seeing at most only five of the rare events per day, Stephenson said. However, the events that they collected will be enough to allow scientists to test their theories about the violation of charge symmetry.

For more information, contact Stephenson at 812-855-5469 or