A long, heavy object from Quantum Field Theory or String Theory, which is very thin. They may have been created in the early life of the Universe, and would now stretch across the entire Universe. No cosmic string has ever been observed. They may or may not exist.
Come, you lost Atoms, to your Centre draw, And be the Eternal Mirror that you saw: Rays that have wander'd into Darkness wide, Return and back into your Sun subside.
From Farid al-Din Attar's twelfth-century masterpiece The Conference of the Birds
The SXS project is a collaborative research effort involving multiple institutions. Our goal is the simulation of black holes and other extreme spacetimes to gain a better understanding of Relativity, and the physics of exotic objects in the distant cosmos.
The SXS project is supported by Canada Research Chairs, CFI, CIfAR, Compute Canada, Max Planck Society, NASA, NSERC, the NSF, Ontario MEDI, the Sherman Fairchild Foundation, and XSEDE.