Cosmic Strings

"A cosmic string is, put simply, a flaw. A crack. A defect. A fold in the very fabric of spacetime itself. If they exist, they were made in the earliest moments of the big bang, when the insane energies were capable of twisting and distorting spacetime so much that it left permanent wrinkles.

These wrinkles, known as cosmic strings, would be almost impossibly thin, no wider than a single proton. But that would pack a potent punch. At those densities, a stretch of cosmic string only a mile long would weigh more than the entire planet Earth. Based on our theories of how they would form, they could stretch from one of the observable universes to the other.

But ... we don’t know if they exist."

- Paul M. Sutter
The Sheer Awesomeness and Weirdness of Cosmic Strings