Big Bang Nucleosynthesis

•It is the leading explanation about how the universe began. At its simplest, it says that the universe started with a small singularity and then inflated over the next 13.8 billion years to the cosmos currently observed.
•The Universe's light-element abundance is another important criterion by which this theory is verified.
•It is now known that the elements observed in the Universe were created in either of two ways.
•Light elements (namely deuterium, helium, and lithium) were produced in the first few minutes of the Big Bang, while elements heavier than helium are thought to have their origins in the interiors of stars which formed much later in the history of the Universe.
•The theory predicts that roughly 25% the mass of the Universe consists of Helium. It also predicts about 0.01% deuterium, and even smaller quantities of lithium.