If you made a wish on every star in the universe, you’d need to make about a trillion trillion wishes—that’s a 1 followed by 24 zeros. Well, the universe also has a low-level background of ultraviolet, visible, and infrared light. This is called the extragalactic background light (EBL), and is the result of the light emitted by all of the galaxies over the entire history of the universe. This is more likely to happen when gamma rays travel an especially long distance through the EBL or through a high density of EBL photons. Since the EBL at any given time reflects the total amount of starlight produced, the reconstruction sheds light on the history of star formation.The team's data suggests that, over the entire history of the universe, stars have produced a total of about 4*10photons.