Cosmological lithium problem

The Cosmological Lithium Problem refers to an observed discrepancy between the predicted abundance of lithium-7 (^7Li) in the universe according to Big Bang nucleosynthesis (BBN) models and the abundances measured in old, low-metallicity stars. Big Bang nucleosynthesis, which describes the formation of light elements in the first few minutes after the Big Bang, predicts specific primordial abundances of hydrogen, helium, deuterium, and lithium.