Scientists re-weigh the electron, get more precise mass

A trap used to hold ions. Bottle cap presumably for scale.

Michigan State University

Ernest Rutherford, pioneer in studying the world inside atoms, famously remarked that all science is either physics or stamp collecting. But sometimes physics itself involves dutifully collecting the stats on the world, in the same way that a naturalist might capture and examine butterflies.

A precise value for the mass of the electron is one example of the sort of statistic that physicists are eager to collect. Last Wednesday in Nature, a team of German physicists reported a new electron-mass measurement that offers a precision to parts per trillion. It is a “remarkable 13-fold increase in precision,” according to Florida State University physicist Edmund G. Myers, who published an accompanying perspective on the research paper.

Scientists have been on a quest for a better and better value of the tiny particle's size for decades. The goal with each new measurement is to get closer and closer to the true value of m_e, which sharpens our understanding of the way that atoms form molecules and is key to a variety of important calculations.