Traces of vast cosmic strings have been found in radiation from the early universe, a controversial new study says. If confirmed to exist, cosmic strings could offer an unprecedented window into the extreme physics of the infant universe.

Snags in the fabric of space may have developed a fraction of a second after the universe's birth – perhaps at the end of a period called inflation when the universe was rapidly expanding.

It is thought that these snags would be shaped like very slender strings, with a thickness far less than the width of an atom but with lengths measured in light years. They would also be very heavy, with a section just a kilometre long potentially having as much mass as the Earth.

Now a team of scientists says that traces of cosmic strings can be detected in the afterglow of the big bang. Led by Neil Bevis of Imperial College London, UK, the team used the Wilkinson Microwave Anisotropy Probe (WMAP) satellite to observe radiation called the cosmic microwave background.