Shedding light on electron's structure - Purdue Univ physicists discover that an electron's electronic strength may increase as it nears a particle's central core - Brief Article

USA Today (Society for the Advancement of Education), June, 1997

An electron may not be exactly what has been thought since its discovery 100 years ago. According to recent measurements by physicists at Purdue University, West Lafayette, Ind., the tiny particle may not be a simple negative point charge, as scientists often describe it.

Science and engineering students have learned for years that the electron has a constant electronic strength. but now we've seen that this may not be the case," explains David Koltick, professor of physics. His research shows that the electromagnetic force from the electron, or its electronic strength, may increase while moving toward the particle's central core.

According to his data, surrounding the electron's core is a fuzzy "cloud" of virtual particles, which wink in and out of existence in pairs. One particle in the pair is positively charged; the other, negatively charged. The cloud is polarized, meaning that the strong negative charge at the core "pushes" the negatively charged particle in a pair slightly farther away from the core than the positively charged particle. The polarization is strongest toward the center of the cloud.

The polarized pairs essentially cancel each other out so that they do not "add" any net electric charge to the electron, Koltick says, but the cloud plays a key role in how the electromagnetic force from the electron is perceived. "The cloud of virtual particles acts like a screen or curtain that shields the true value of the central core. As we probe into the cloud, getting closer and closer to the core charge, we `see' less of the shielding effect and more of the core. This means that the electromagnetic force from the electron as a whole is not constant, but rather gets stronger as we go through the cloud and get closer to the core. Ordinarily when we look at or study an electron, it is from far away and we don't realize the core is being shielded."

Koltick and his colleagues also determined that the strong nuclear force, which is the "glue" that holds together elementary particles such as protons, gets weaker closer to the core charge. "Because the electromagnetic charge is in effect becoming stronger as we get closer and the strong force is getting weaker, there is a possibility that these two forces may at some energy be equal. Many physicists have speculated that when and if this is determined, an entirely new and unique physics may be discovered."