Medieval alchemists dreamed of transmuting lead into gold. Today, we know that lead and gold are different elements, and no amount of chemistry can turn one into the other.

But our modern knowledge tells us the basic difference between an atom of lead and an atom of gold: the lead atom contains exactly three more protons. So can we create a gold atom by simply pulling three protons out of a lead atom?

As it turns out, we can. But it’s not easy.

While smashing lead atoms into each other at extremely high speeds in an effort to mimic the state of the universe just after the Big Bang, physicists working on the ALICE experiment at the Large Hadron Collider in Switzerland incidentally produced small amounts of gold. Extremely small amounts, in fact: a total of some 29 trillionths of a gram.