Thevortex theory of the atom was a 19th-century attempt byWilliam Thomson (later Lord Kelvin) to explain why theatoms recently discovered by chemists came in only relatively few varieties but in very great numbers of each kind. Based on the idea of stable, knotted vortices in the ether oraether, it contributed an important mathematical legacy.
The vortex theory of the atom was based on the observation that a stablevortex can be created in a fluid by making it into a ring with no ends. Such vortices could be sustained in theluminiferous aether, a hypothetical fluid thought at the time to pervade all of space. In the vortex theory of the atom, a chemicalatom is modelled by such a vortex in the aether.
Knots can be tied in the core of such a vortex, leading to the hypothesis that eachchemical element corresponds to a different kind of knot. The simpletoroidal vortex, represented by the circular "unknot" 01, was thought to representhydrogen. Many elements had yet to be discovered, so the next knot, thetrefoil knot 31, was thought to representcarbon.
Between 1870 and 1890 the vortex atom theory, which hypothesised that anatom was avortex in theaether, was popular among British physicists and mathematicians.William Thomson, who became better known as Lord Kelvin, first conjectured that atoms might be vortices in the aether that pervades space. About 60 scientific papers were subsequently written on it by approximately 25 scientists.
In the seventeenth centuryDescartes developed a theory of vortex motion to explain such things as why light radiated in all directions and the planets moved in circular orbits. He believed that there was no vacuum and any object which moved had to be entering a gap left by another moving object. He realised that a circular chain of such objects, all replacing each other, would enable such movement. Thus, all movement consisted of endless circular vortices at all scales. However Descartes model consisted of tiny whirling particles rather than a strictly continuous medium of the vortex theory of atoms.[1]: 33
Hermann Helmholtz, working on thehydrodynamics ofidealized fluids, realized in the mid-19th century that the core of a vortex, analogous to the eye of a hurricane, is a line-like filament and in a perfect frictionless fluid these filaments can form closed rings. Helmholtz also showed that vortices exert forces on one another, and those forces take a form analogous to the magnetic forces between electrical wires. However Helmholtz made no connection theories of matter.[1]: 36
During the intervening period, chemistJohn Dalton had developed hisatomic theory of matter. It remained only to bring the two strands of discovery together.
William Thomson, later to become Lord Kelvin, became concerned with the nature of Dalton'schemical elements, whose atoms appeared in only a few forms but in vast numbers. He was inspired by Helmholtz's findings, reasoning that theaether, a substance then hypothesised to pervade all of space, should be capable of supporting such stable vortices. According to Helmholtz’s theorems, these vortices would correspond to different kinds ofknot. Thomson suggested that each type of knot might represent an atom of a different chemical element. He further speculated that multiple knots might aggregate intomolecules of somewhat lower stability.
He published his paper "On Vortex Atoms" in theProceedings of theRoyal Society of Edinburgh in 1867.[2][3]
Thomson's colleaguePeter Guthrie Tait was attracted by the vortex atom theory and undertook a pioneering study of knots, producing a systematic classification of those with up to 10 crossings, in the hope of thus systematizing the various elements.
J. J. Thomson took up the challenge in his 1883 Master's degree thesis, aTreatise on the motion of vortex rings.[4][5] In it, Thomson developed a mathematical treatment of the motions of William Thomson and Peter Tait's atoms.[6]
When Thomson later discovered the electron (for which he received aNobel Prize), he abandoned his "nebular atom" hypothesis based on the vortex atomic theory, in favour of hisplum pudding model.
By 1883 William Thomson began to see that the theory could not do all of the things he hoped. It could not explaininertia orgravitation and, worse Helmholtz's circular ring was not ultimately stable. Even the properties of crystals, and of electrical and chemical forces were unexplainable in the model. However in an era with increasing evidence for atomic theory and no viable alternative model, the vortex theory was highly influential.[7]: 473
Tait's work especially founded the branch oftopology calledknot theory,[1]: 93 with J. J. Thomson providing some early mathematical advancements.The vortex theory was not successful as a model for the atom, but the theoretical development of the theory had a lasting impact on theoreticalhydrodynamics.[7]In 1961, inspired by Kelvin's motivation and results,Tony Skyrme introducedsolitons to build a model fornucleons.[1]: 93 These solitons were topologically stable vortices of a 'pion fluid' and were later calledskyrmions.[8]
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