Cosmic strings - imperfections in space-time - may be to blame for two unusual bursts of gamma rays in the early universe.
Gamma-ray bursts come in two types. Long-lived, high-intensity bursts are thought to originate from collapsing stars, while shorter, dimmer ones are emitted when neutron stars merge with one another or with black holes.
In 2008 and 2009 two unusual bursts were seen, both short-lived but with the brightness of long bursts. Both occurred within a billion years of the big bang.
K. S. Cheng of the University of Hong Kong and colleagues say the culprit could be cosmic strings - defects in space-time, like streaks in clear plastic, that formed as the early universe cooled.
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