A Knot is defined as a closed 3-Dimensional curve that does not intersect itself. The main implementation of the Knot Theory started in the late 1880's, most scientists believed that the universe was pervaded with ether, and all matter was thought to be entangled in it. Lord Kelvin,(William Thomson, 1824-1907) proposed that different elements consisted of different configurations of knots. He described atoms to be knots in the fabric of this ether. This theory led many scientists to believe that they could understand the chemical elements by simply studying different types of knots and thus this led to a completely new field of study in math.
However, soon enough the atomic revolution dismissed the theory of ether, and mathematicians were left alone in pursuit of Knot Theory for almost a century.
In the 1980's, biologists and chemists studying genetics found that deoxyribonucleic acid (DNA) can sometimes become tangled. Experiments suggested that how a DNA strand knots might have an impact on the properties of the resulting strand after replication.