A preprint is available on the arXiv server. Quipu was named after the knotted cords used as recording devices by the Inca Empire and other South American cultures. It resembles those cords ...

The Incas had a system of accounting that relied on the quipu. Cords of various colours were attached to a main cord with knots. The number and position of knots as well as the colour of each cord ...

Quipu is estimated to span an astonishing ... which is near the former home of the Inca Empire. By detecting radiation emitted by the galaxy clusters, scientists were able to confirm the presence ...