arXiv subjects

Mitchell J. Feigenbaum

Publications and source records attributed to Mitchell J. Feigenbaum.

3 recordsLinked to original sources

arXiv2008

The Theory of Relativity - Galileo's Child

We determine the Lorentz transformations and the kinematic content and dynamical framework of special relativity as purely an extension of Galileo's thoughts. No reference to light is ever required: The theories of relativity are logically independent of any properties of light. The thoughts of Galileo are fully realized in a system of Lorentz transformations with a parameter 1/c^2, some undetermined, universal constant of nature; and are realizable in no other. Isotropy of space plays a deep and pivotal role in all of this, since here three-dimensional space appears at first blush, and persists until the conclusion: Relativity can never correctly be fully developed in just one spatial dimension.

physics.class-ph↗

arXiv2002

Pattern Selection: Determined by Symmetry and Modifiable by Long-Range Effects

We consider Saffman-Taylor channel flow without surface tension on a high-pressure driven interface, but modify the usual infinite-fluid in infinite-channel configuration. Here we include the treatment of efflux by considering a finite connected body of fluid in an arbitrarily long channel, with its second free interface the efflux of this configuration. We show that there is a uniquely determined translating solution for the driven interface, which is exactly the 1/2 width S-T solution, following from correct symmetry for a finite channel flow. We establish that there exist no perturbations about this solution corresponding to a finger propagating with any other width: Selection is unique and isolated. The stability of this solution is anomalous, in that all freely impressible perturbations are stabilities, while unstable modes request power proportional to their strength from the external agencies that drive the flow, and so, in principle, are experimentally controllable. This is very different from the behavior of the usual infinite fluid: The limit of infinite length is singular, and not that of the literature. We argue that surface tension on the efflux interface decreases the finger-width by the ratio of its surface tension to velocity of the high-pressure tip. The perturbation theory created here to deal with transport between two free boundaries is novel and dependent upon a remarkable symmetry.

cond-mat.soft↗

arXiv1999

Dynamics of Finger Formation in Laplacian Growth without Surface Tension

We study the dynamics of "finger" formation in Laplacian growth without surface tension in a channel geometry (the Saffman-Taylor problem). Carefully determining the role of boundary geometry, we construct field equations of motion, these central to the analytic power we can here exercise. We consider an explicit analytic class of maps to the physical space, a basis of solutions for infinite fluid in an infinitely long channel, characterized by meromorphic derivatives. We verify that these maps never lose analyticity in the course of temporal evolution, thus justifying the underlying machinery. However, the great bulk of these solutions can lose conformality in time, this the circumstance of finite-time singularities. By considerations of the nature of the analyticity of all these solutions, we show that those free of such singularities inevitably result in a {\em single} asymptotic "finger". This is purely nonlinear behavior: the very early "finger" actually already has a waist, this having signalled the end of any linear regime. The single "finger" has nevertheless an arbitrary width determined by initial conditions. This is in contradiction with the experimental results that indicate selection of a finger of width 1/2. In the last part of this paper we motivate that such a solution can be determined by the boundary conditions when the fluid is finite. This is a strong signal that {\em finiteness} is determinative of pattern selection.

chao-dyn↗