Scientists have found two interstellar clouds of original gas, which -- unlike everything else in the universe -- has never mingled with elements forged later in stars. The existence of pristine gas that formed minutes after the Big Bang explosion some 13.7 billion years ago, had been predicted, but never before observed.
The clouds, which are located about 12 billion light-years from Earth within the constellations Ursa Major and Leo, were found serendipitously during an ongoing study to characterize gas in distant galaxies.
In analyzing the light coming from quasars (active nuclei of distant galaxies), astronomers realized the rays had passed through gas that contained only hydrogen and deuterium, elements that formed minutes after the Big Bang.
The surprise was that the clouds contained nothing else -- no carbon, no nitrogen, no silicon, no iron -- none of the heavier elements forged in stars and spread throughout the universe.