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.
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.
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.
Mathematical knots
Mathematical knots, or knots which are studied in the field of knot theory, are based on the embedding of a circle within three-dimensional space. They are different from the usual idea of a knot, that is, a string with free ends. Therefore, mathematical knots are (almost) always considered to be closed loops.