The discovery by UC Santa Cruz astronomers of pristine clouds of gas formed shortly after the Big Bang is among the scientific breakthroughs of the year featured in year-end issues of Science and Physics World magazines.

Astronomy professor J. Xavier Prochaska and graduate student Michele Fumagalli, along with John O'Meara of Saint Michael's College in Vermont, reported in November the first ever detection of clouds of the primordial gas that formed in the first few minutes after the Big Bang. Their discovery made Physics World magazine's list of the "top 10 breakthroughs for 2011" and was featured as one of nine runners-up to the "Breakthrough of the Year" in Science magazine. (Science named the finding that HIV treatment reduces transmission rates as the top breakthrough.)

The top-ten list in Physics World was compiled by an editorial team which reviewed over 350 news articles about breakthroughs in the physical sciences published on their web site in 2011. Science magazine's choices were made "after much deliberation involving our News and Editorial staff, plus our Board of Reviewing Editors."

Prochaska and Fumagalli analyzed light from distant quasars to detect two pristine clouds of hydrogen gas. Their observations matched theoretical predictions for the primordial gas formed after the Big Bang, providing direct evidence in support of the modern cosmological explanation for the origins of elements in the universe.

For more on their discovery, see "Astronomers find clouds of primordial gas from the early universe."