Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-24T13:04:05.983Z Has data issue: false hasContentIssue false

Zeeman's Catastrophe Machine

Published online by Cambridge University Press:  24 October 2008

T. Poston
Affiliation:
Mathematical Institute, The University of Warwick
A. E. R. Woodcock
Affiliation:
Mathematical Institute, The University of Warwick

Extract

René Thom(5) has shown that if the state of a system is determined by the local minimization of a potential – that is, if the system is so highly dissipative that transients can safely be ignored–then, though a smooth change in the potential function may give rise to a discontinuous change of state, the ways in which this can happen are quite limited. Infact, if we have at most a four-parameter family of potentials, discontinuities of this kind can occur in only seven ways up to local diffeotype, if they are to be structurally stable. (This latter condition is the requirement that it be im-possible to alter the discontinuity type by an arbitrarily small perturbation of the family of potentials: roughly it requires that the behaviour of the system, considered as a function of possible families ofpotentials, be ‘continuous’ at the family concerned. It bears the same relationship as does continuity to computability: a computer given approximately correct data for which to compute the value of a function or the behaviour of a system will give an approximately correct answer if the function is continuous, the system structurally stable. If not, only analytic methods will serve, and the physical significance of the result will be dubious. Fortunately, in the dimensions with which we are concerned, structural stability is an open dense property in the space of possible families of potentials; thus unstable systems can be ignored for almost all purposes, just as we ignore the ‘possibility’ of balancing a pin on its point.)

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1973

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

(1)Edwards, J.An elementary treatise on the differential calculua, with applications and numerous examples (Macmillan, London, 1892).Google Scholar
(2)Fowler, D. The Riemann-Hugoniot catastrophe and Van der Waal's equation. In Towards a theoretical biology, vol. iv, ed. Waddington, C. H. (Edinburgh University Press, to appear.)Google Scholar
(3)Klein, F.Famous problems of elementary geometry (Göttingen 1895, 1897, trans. Beman, Wooster Woodruff & Smith, David Eugene, most recentedition Chelsea Publishing Co., New York, 1962).Google Scholar
(4)Pappus or Alexandria, Bk iv, Synagoge, circa A.D. 300.Google Scholar
(5)Thom, R.Stabilité structurelle et morphogénèse (to appear).Google Scholar
(6)Woodcock, A. E. R. and Poston, T.The geometry of the elementary catastrophes Springer-Verlag, Lecture Notes in Mathematics, (to appear).Google Scholar
(7)Zeeman, E. C. Differential equations of the heartbeat and nervous impulse. In Towards a theoretical biology, vol. iv, ed. Waddington, C. H. (Edinburgh University Press, to appear).Google Scholar
(8)Zeeman, E. C. A catastrophe machine. In Towards a theoretical biology, vol. iv, ed. Waddington, C. H. (Edinburgh University Press, to appear).Google Scholar
(9)Zeeman, E. C.Applications of catastrophe theory. Bull. Lond. Math. Soc. (to appear).Google Scholar