Astronomy
Gamma-ray bursts as probes of the early universe
Quick fact
The most distant known gamma-ray burst, GRB 090423, exploded just 630 million years after the Big Bang, when the universe was only about 4.5% of its current age.
Why this is interesting
Imagine witnessing an explosion so bright that it outshines every star in the universe combined—but only for a few seconds. How can such a fleeting flash from billions of light-years away tell us about the universe's very first stars?