BaBar Discovery a Top 10 Breakthrough in Physics in 2012

By Lori Ann White
December 14, 2012

Each year, the editors of Physics World select what they consider the top 10 breakthroughs in the world of physics. After combing through more than 350 possibilities, they’ve come up with their selections for 2012 – and a discovery by the scientists of the BaBar experiment, which ran at SLAC from 1999 to 2008, is No. 3 on the list.

The breakthrough: the first direct observation of time reversal violation. This is a tiny difference between the time a certain type of subatomic particle takes to flip from one state into another, and the time it takes to flip back again.

The list of criteria for making the cut – determined by the Physics World editorial team – includes the fundamental importance of the research, whether the discovery results in a significant advance in knowledge, whether it represents a strong connection between theory and experiment and whether it’s of general interest to all physicists.

“Having the value of this result recognized in this way is a real honor for BaBar,” said BaBar spokesperson Michael Roney of the University of Victoria. “It is an outcome of the close collaborative effort of many people from BaBar, the PEP-II accelerator team, the Department of Energy and SLAC, as well as the funding agencies in each of our countries. This provides an excellent opportunity to express our appreciation to them for their continuing support.”

Read about all top 10 breakthroughs at


Image - Mirror images of "B" with clocks inside.
Two different B mesons changing between states (represented as colors). However, blue-B changes into red-B more quickly than red-B changes into blue-B (a process running in reverse-time, as shown by the backwards clock dial).