Big Bang Confirmed Again, This Time By The Universe's First Atoms
“If anything could throw the Big Bang into crisis, it would be if a truly pristine sample of gas disagreed with the predictions of how the elements should turn out. But everything lines up so incredibly well, between the theory of what we should observe just three-to-four minutes after the Big Bang and the observations we make billions of years later, that it can only be considered a remarkable confirmation of the most successful theory of the Universe ever. From the smallest, subatomic particles to the largest cosmic scales and structures, the Big Bang explains an enormous suite of phenomena that no other alternative can touch.”
When it was first conceived, the idea of the Big Bang was spectacular for the fact that it made three incredibly distinct predictions, ranging from the largest scales down to the smallest. As we looked from million to billions of light years away, we should find that the Universe expands at a rate that changes depending on what’s in it; there should be a leftover, uniform glow in all directions; and the first atoms, before stars formed, should exist in a very particular abundance. These ratios were notoriously difficult to observe, because it required a serendipitous alignment of an ultra-distant light source behind a pristine cloud of gas that never formed stars. And yet, here in the 21st century, we’ve actually found multiple systems that have those exact properties! One can calculate the expected abundances from Big Bang nucleosynthesis, and the measurements are finally getting good enough to compare the results with the predictions. The agreement is beyond spectacular!
The Universe’s first atoms, forged just four minutes into the Universe but observed billions of years later, confirm the Big Bang yet again.