Understanding the cosmic origin of all the elements heavier than hydrogen can give us a powerful window into the Universe’s past, as well as insight into our own origins. Image credit: Wikimedia Commons user Cepheus.

The rarest light elements in the Universe

There’s a big gap between Helium and Carbon. Come find out why!

“And argon, krypton, neon, radon, xenon, zinc and rhodium,
And chlorine, cobalt, carbon, copper, tungsten, tin and sodium.
These are the only ones of which the news has come to Harvard,
And there may be many others, but they haven’t been discarvard.”
-Tom Lehrer

Immediately after the Big Bang, before the first stars in the Universe ever formed, the Universe consisted of hydrogen (element #1), helium (element #2) and pretty much nothing else. Despite originating from an incredibly hot, dense state, arbitrarily heavy elements weren’t created early on the same way they’re made today in stars. Despite being hot enough to make pretty much anything, the early Universe makes almost nothing for one simple reason: if it was hot-and-dense enough to fuse elements together in the very early stages, it was also hot enough to blast those composite elements apart again.

It’s only when the Universe has cooled enough that elements aren’t immediately split apart — a little more than three minutes in — that we can build our way up the periodic table.