Primordial Helium, Left Over From the Big Bang, is Leaking Out of the Earth

Something ancient and primordial lurks in Earth’s core. Helium 3 (3He) was created in the first minutes after the Big Bang, and some of it found its way through time and space to take up residence in Earth’s deepest regions. How do we know this? Scientists can measure it as it slowly escapes. About five …