Particles Retain Weight for Billions of Years

Unlike most of us, subatomic particles don't gain weight as they get older. The mass of these tiny bits of matter has remained constant over the last 6 billion years, recent astronomical observations indicate.

Believe it or not, but whether an electron was lighter or heftier in the past is a question of fundamental importance. Variations in particle masses and other so-called constants of nature, such as the speed of light, may help explain the mystery of dark energy and determine if hidden dimensions exist.

"Some theorists claim the physical constants should have varied over time," said Christian Henkel of the Max Planck Institute for Radio Astronomy in Bonn, Germany. "This is something that is part of the modeling of the universe."

Henkel and his colleagues have placed new limits on wavering constants. By observing the absorption of radio waves by molecules in the early universe, the researchers have shown that the mass ratio between two particles — the proton and the electron — has not changed from its present value by more than 2 parts in a million.

The results, reported in a recent issue of the journal Science, call into question previous measurements that claim to have seen variations in this mass ratio. - continued on space.com