Of all the elements of the periodic table, lithium has perhaps the most complicated and mysterious origins, in part because it can be created in so many ways. Its dominant isotope, 7Li, is one of the few species (along with deuterium, helium-3, and helium-4) to have been produced in Big Bang nucleosynthesis. Cosmic-ray spallation—nuclear fission initiated when energetic protons and other particles collide with interstellar carbon, nitrogen, and oxygen—is a significant source of Li, beryllium, and boron. And Li can be both produced and destroyed in stars, although questions remain about the nature of the stellar sources and how much Li they produce. In the effort to derive a clear picture of the chemical evolution of our galaxy by combining observations of elemental abundances with their known mechanisms of creation and destruction, the so-called “lithium problem” has been an especially tough one to crack.

Now Akito Tajitsu, of the...

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