Gamma ray bursts (GRBs) are the brightest events in the known universe. These flashes of high-energy light occur about once a day, randomly, from around the sky.
The universe was created 13.73 billion years ago in a blaze of light: the big bang. Roughly 380,000 years later, after matter (mostly hydrogen) had cooled enough for neutral atoms to form, light was able to traverse space freely.
The first stars in the Universe are believed to have formed only a few hundred million years after the big bang, about 13.7 billion years ago.
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