New observations with the James Webb Space Telescope reveal that dwarf galaxies in the early universe released enough collective radiation to change the cosmos forever.
Astronomers have used the James Webb Space Telescope (JWST) and an effect predicted by Albert Einstein over 100 years ago to discover that small galaxies in the early cosmos packed a massive punch, shaping the entire universe when it was less than 1 billion years old. The international team found the galaxies, which resemble dwarf galaxies that exist today, played a vital role during a crucial stage of cosmic evolution that occurred between 500 and 900 million years after the Big Bang. These small galaxies also vastly outnumbered larger galaxies in the infant universe, the scientists say, adding that it's likely the realms supplied most of the energy needed for a process called cosmic reionization. Cosmic reionization was critical to the growth and progression of the universe. "We're really talking about the global transformation of the entire universe," Hakim Atek, research lead author and an astronomer at the Institut d'Astrophysique de Paris, told Live Science's sister site Space.com. "The main surprise is that these small, faint galaxies had so much power, their cumulative radiation could transform the entire universe." Small driving forces behind major changes Prior to around 380 million years after the Big Bang happened, during a period called the epoch of recombination, the now 13.8 billion-year-old universe had been opaque and dark. This was because, in its dense and ultra-hot state, free electrons endlessly bounced around particles of light, called photons. Related: After 2 years in space, the James Webb telescope has broken cosmology. Can it be fixed? Later, during the epoch of recombination, however, the universe had expanded and cooled enough to allow electrons to bond with protons and create the first atoms of hydrogen, the lightest and simplest element in the cosmos. This disappearance of free electrons meant photons were suddenly free to travel, and as a result, the "dark age" of the universe ended. The cosmos suddenly became transparent to…