'Background' light of universe measured

The brightness of the background of light photons that has filled the universe since its formation has been measured for the first time, French researchers say. Scientists at the country's National Center for Scientific Research say their findings could provide new insight into the size of the universe, the formation of stars and the evolution of galaxies. The light emitted by all the objects in the universe, such as stars and galaxies, ever since its birth fills intergalactic space with an "ocean" of photons known as the "diffuse extragalactic background light," the researchers said. The shine of our own galaxy makes it impossible to directly measure this fossil record of the light emitted in the universe, so astrophysicists made use of gamma rays, with energy more than 500 billion times greater than that of visible light, as an alternative, indirect method of measuring this light, a release from the center said. These measurements made it possible to estimate for the first time the intensity of the starlight contained within all the universe at wavelengths ranging from the near infrared to the ultraviolet, including visible wavelengths, it said. A better understanding of this diffuse light should yield information about the first stars, shedding light on their formation and on the evolution of galaxies, astronomers said.