If the existence of cosmic strings is confirmed, it would be huge. They could help uncover the Holy Grail of physics: a theory of everything. And in the far future, they might even enable us to time travel.
The theories that predict their existence suggest that cosmic strings are thinner than an atomic nucleus. Prof Ken Olum, of Tufts University, describes them as astronomically long tubes. “They would most likely exist in the form of either loops or long strings that go on and on forever,” he says.
But while the strings are super thin, they can pack in a lot of mass. “A typical loop, which may be about 10–20 light-years long, can contain around the equivalent of the mass of tens of thousands of stars,” says Olum. But it’s thought they’d shrink over time as the tubes wiggle, radiating gravitational waves.