We have long struggled to figure out where heavy elements like gold come from. Now we have seen them being forged in neutron star collisions – and fresh clues suggest a role for the universe’s first stars
21 July 2021
EVERYONE knows that ancient alchemists were obsessed with making gold. They never cracked it. Everyone knows that too. But here’s something not a lot of people know: thousands of years later, we still don’t fully understand where gold comes from. We can find it on Earth, of course. But where in the universe it was first made has long been a cosmic-scale mystery.
For most of the elements we are familiar with – carbon, oxygen, nitrogen – their origins are clear. These atoms were cooked up in the roiling hearts of stars through nuclear fusion. But bog-standard fusion is only powerful enough to produce relatively light elements. To create heavier stuff, a more powerful process is needed. The thing is, we don’t know exactly how or where it happens. This applies not just to gold, but to dozens of the heavier, more exotic elements. You could say that the origins of half the elements on the periodic table are unknown.
There is no shortage of possible explanations, each of which involves the fiery deaths of stars or other celestial implosions. Now, though, we finally have some hard evidence. For the first time, we have spotted heavy elements actually being made. In exploring further, we have learned that their origins are probably far more subtle than we ever suspected.
The chemical elements are the basic building blocks of everything, including you. Along with rather a lot else, an adult body contains somewhere in the region of 16 kilograms of carbon, 780 grams of phosphorus and 0.2 milligrams of gold. Deep down, every element is made of the same three particles. There …