Cross-section of the Earth’s interior: crust, upper- and lower-mantle, and outer- and inner-cores. Credit: Mikio Fukuhara, Alexander Yoshino, and Nobuhisa Fujima ========================================================================= Rather than being created solely during supernova explosions, chemical elements could also be produced deep within the Earth’s lower mantle. It has long been theorized that hydrogen, helium, and lithium were the only chemical elements in existence during the Big Bang when the universe formed, and that supernova explosions, stars exploding at the end of their lifetime, are responsible for transmuting these elements into heavier ones and distributing them throughout our universe. Researchers in Japan and Canada are...