The Surprising Origin of All the Elements in the Universe?

The universe, shortly after the Big Bang, only contained light elements like hydrogen, helium, and lithium. Yet, today we find much heavier elements. This segment poses the fundamental question of where these elements, including carbon, nitrogen, and oxygen vital for life, originated.

In the first minutes after the Big Bang, a process called nucleosynthesis created the nuclei of the first atoms: primarily 75% hydrogen and 25% helium, with trace amounts of other isotopes. After 380,000 years, the universe cooled enough for recombination to occur, forming neutral hydrogen and helium atoms. This left only the first two elements of the periodic table.

As hydrogen gas condensed, the first stars formed, initiating fusion. In these stars, hydrogen atoms fused to form helium, releasing energy. This fusion process continues to produce heavier elements. However, stars like our sun, being medium-sized, can only fuse elements up to carbon and nitrogen because fusing heavier elements yields less energy, making them lose the battle against gravity.

Larger stars can continue the fusion process to produce elements up to iron. Iron is the most stable nucleus and its fusion does not release energy, causing the process to stop. When massive stars die, they explode in a supernova, generating extreme temperatures that drive additional nucleosynthesis, forming elements heavier than iron, up to zirconium. Most of the iron on Earth also comes from these supernovae.

Smaller stars, like our sun, don't end in supernovae but can produce heavier elements through neutron capture. Excess neutrons from fusion are absorbed by existing heavy elements, and then some neutrons transmute into protons, forming new, heavier elements. This process can create elements from strontium all the way to lead and bismuth.

The heaviest elements, up to plutonium (element 94), are believed to be formed in the mergers of two neutron stars. These events release a massive abundance of neutrons that are absorbed by heavy atoms, which then undergo transmutation, creating the super-heavy elements.

Naturally occurring super-heavy elements beyond plutonium have very unstable isotopes and are found near radioactive sources, produced in minute amounts from the neutron absorption by elements like uranium. Man-made elements constitute the remaining 20 on the periodic table. Boron, beryllium, and some lithium are uniquely produced by cosmic rays splitting heavier elements. Despite the diversity, 98% of the visible matter in the universe is made of just hydrogen and helium, with all other 96 elements making up only 2%. The elements necessary for life, though a small percentage, are readily found throughout the universe.