These are knots. Not knots used to tie down boats or headstrong horses, but knots used to explore geometries of space.
The display was made by Estes Objethos Atelier, but the photo was taken by Rodrigo Argenton. As it says on Wikimedia Commons, where I found this in the “Knot Theory” collection: “Please attribute as Matemateca (IME/USP)/Rodrigo Tetsuo Argenton. This file was published as the result of a partnership between Matemateca (IME/USP), the RIDC NeuroMat and the Wikimedia Community User Group Brasil.”
You can see the equations or notation describing each knot underneath its loop of white cord.
Knot Theory is the study of mathematical knots, which are knots that can’t be untied. Wikipedia:
While inspired by knots which appear in daily life, such as those in shoelaces and rope, a mathematical knot differs in that the ends are joined so it cannot be undone, the simplest knot being a ring (or “unknot”). In mathematical language, a knot is an embedding of a circle in 3-dimensional Euclidean space, E3.
It gets pretty hairy from there, but you get the idea. The applications are interesting, touching on everything from magnetic containment fields (think: particle beams and fusion generators) to protein-folding (think: new drugs) and quantum physics.