Finding the first atoms in the Universe
"In theory, extraordinarily isolated clumps of matter, whose mass totals something like only 0.0001% of our Milky Way Galaxy, may survive without forming any stars at all, and without being polluted by any nearby post-stellar mass, for well over a billion years. But if we wanted to find one, we’d have to be incredibly lucky. From the time the Big Bang first was proposed as a theory in the 1940s, we didn’t have that luck for years, and then decades, and then for generations.
But then 2011 came along, and we’ve had two strokes of luck that serendipitously have given us the luck we’ve been waiting for!”
The Big Bang has, among its predictions, three cornerstones: the Hubble Expansion of the Universe, the Cosmic Microwave Background, and the abundance of the Light Elements due to Big Bang Nucleosynthesis. The first one has been confirmed to spectacular accuracy, and with the COBE, WMAP and Planck satellites, the spectrum and fluctuations in the CMB rule out almost every other feasible alternative. But detecting the abundance of the light elements directly has always run into a difficulty: the formation of stars in the Universe pollutes the intergalactic medium, ruining our ability to see anything “pristine.” We’d have to get incredibly lucky, to find a region of molecular gas that had never formed stars in-between our line-of-sight to a quasar or bright galaxy. For nearly 70 years, that didn’t happen, and then all of a sudden, we found two. The Big Bang stands tall after all!