The AEther

In early modern physics, the luminiferous aether (or ether) was believed to be an invisible space-filling substance or field that was a transmission medium for electromagnetic or gravitational forces.

Tait conjectures

Peter Guthrie Tait (1837-1901) was a Scottish mathematical physicist, whose investigations in knot theory contributed to the field of topology as a mathematical discipline. His tabulations of knots with ten crossings, which became known as the Tait conjectures, arose out of experiments he conducted with William Thomspon (Lord Kelvin) in 1867 at the University of Edinburgh.

Klein bottle

If you like a drink, then a Klein bottle is not a recommended receptacle. It may look vaguely like a bottle, but it doesn't enclose any volume, which means that it can't actually hold any liquid. Whatever you pour "in" will just come back out again as the Klein bottle is an example of a non-orientable surface. It has no "inside" and no "outside", instead, just a side.

Knots

A knot is an entanglement, an intentional complication in cordage.

Knot Theory

Knot theory is a field of mathematics that studies the topology of knots. In mathematical language, a knot is the embedding of a circle in 3-dimensional Euclidean space, R3.

Unknot

The unknot, or torus, is the first type of mathematical knot listed in knot theory. Intuitively, the unknot is a closed loop of rope without a knot in it.