Cracks in the universe: the search for cosmic strings Galaxy-sized filaments of raw energy may be threaded through spacetime, according to some theories. Will we ever find traces of them? Cathal O’Connell takes up the hunt. Share Tweet Tatyun / Getty Images Our universe exploded into being, expanded at a fantastic speed and cooled. Perhaps too quickly. Some physicists believe the rapid cooling might have cracked the fabric of the universe.These hairline fractures may still be threaded through space-time. Dubbed cosmic strings, mathematical models see them as invisible threads of pure energy, thinner than an atom but light-years long. The...