This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In the early moments of the big bang, two elements were forged: hydrogen and helium. Technically, the tiniest traces of light elements such as lithium were produced as well, but nothing of consequence.
The early universe was about three parts hydrogen to one part helium. All the heavier elements, from the oxygen in your lungs to the iron in your blood, were created through astrophysical processes—fused in stars, formed in supernovae or scattered by the collisions of neutron stars. Even in the present cosmos, heavier elements are so cosmically rare that astronomers group them all as metals.
One of the ways astronomers study the big bang is through the relative abundance of different elements, particularly the primordial abundance of hydrogen and helium. That might seem easy, since they were the two elements formed by the big bang, but there is a catch. Although all the hydrogen we observe was formed during the big bang, not all the helium we observe was.
Most of the helium was formed way back in the beginning, but helium is also the most common byproduct of stellar fusion. So while stars are producing all the atoms we need to make data centers and Labubu dolls, they are also producing lots of helium. This means that over billions of years, the relative abundance of helium has been increasing, and this skews the data.
The Large Binocular Telescope Primordial Helium Abundance (LBT YP) Project is trying to overcome this issue and has recently published a series of results. The study focused on measuring hydrogen and helium levels within metal-poor galaxies. These distant galaxies contain mostly early stars, so they don't have much in the way of heavy elements.
The idea is that if they are low in metals, they also aren't contaminated by stellar helium. Based on a sample of interstellar gas regions within 54 galaxies, the team found that primordial helium makes up 24.58% of the initial matter of the cosmos by mass. This agrees well with the estimate from Planck observations of the cosmic microwave background, which gave a result of 24.67%.
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