Richard H. Miller
University of Chicago
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Featured researches published by Richard H. Miller.
Journal of Computational Physics | 1967
Richard H. Miller
Abstract The numerical stability of evolutionary calculations can be tested experimentally by running two calculations in parallel, starting from initial conditions that are very similar, and monitoring the differences between the systems. An integration of an n -body system with gravitational interactions provides an example that is useful for illustrative purposes. Some features of the method are described, followed by a discussion of some considerations in its application.
Journal of Computational Physics | 1970
Richard H. Miller
Abstract An n -body calculation designed for astronomical studies in stellar dynamics is able to handle large number of particles by restricting the set of points over which force values are required. The resulting model can be treated exactly in a computer by using integer arithmetic; the “data” representing the physical system are modified to conform to the model. Reversibility and an exact Liouville theorem result, making the model close to the physics in the sense that exactly conserved quantities of the model correspond to essential features of the physics. The cost of this pleasing correspondence is a reduction in the accuracy of conserving some of the conventional integrals. While the formulation affords a useful viewpoint for considering the relationship between computer models and the physical systems they represent that is quite different from that underlying conventional calculations, numerical considerations differ only in that the numerical methods used are coarser than with conventional calculations. The numerical approximations and the features responsible for the exact properties are presented in detail. The calculation has been successfully used as a tool for numerical experiments on spiral structure and gravitational stability.
Archive | 1990
Richard Allan Gerber; Susan A. Lamb; Richard H. Miller; Bruce F. Smith
Collisions and close encounters between galaxies have a profound effect upon the galaxies involved, for example, morphological changes can be pronounced. A very obvious effect of interaction on galaxies is a mean increase in their far infrared luminosities as detected by IRAS (Kennicutt et al. 1987; Bushouse, Lamb, and Werner 1988). This observed excess in infrared luminosity has often been invoked as evidence of increased star formation in these systems, but may in some cases be attributable to radiation from shocks in the gas occurring as a direct result of the collision (Harwitt et al. 1987). Of particular interest is the possibility that colliding galaxies are sites of unusual star formation.
Archive | 2003
Richard H. Miller
Some years ago we published an account of experiments which indicated that the nucleus of a galaxy orbits around the mass centroid. This can be viewed as an orbiting density wave which grows near the center in a galaxy model that starts without such motions. While these experiments were run without a massive particle, we suggested that similar physical effects might cause a massive particle near the center to oscillate with larger amplitudes than indicated by simple Brownian motion arguments. Results from recent experiments will be reported to clarify some of the issues raised by a massive particle (a black hole) near the center.
Archive | 1990
Richard Allan Gerber; Susan A. Lamb; Richard H. Miller; Bruce F. Smith
Interacting galaxies have a mean increase in their far infrared luminosities as detected by IRAS [1], and this observed excess in infrared luminosity has often been invoked as evidence of increased star formation [2].We have used the N-body models described in [3,5] to obtain information which is useful in probing some aspects of the relationship between galaxy collisions and star formation. The models are the result of fully self consistent calculations of spherical galaxies in which the self-gravity of each galaxy is included. The collisions are deeply interpenetrating with the galaxies initially either on parabolic or mildly hyperbolic orbits.The encounters are of equal mass galaxies or galaxies with a mass ratio of 2:1 and some include cold, thin, rotating disks.
Science | 1969
Richard H. Miller
The value of 31.56 � 0.74 days for the synodic month in the Upper Cambrian is used together with a maximum in the expected number of days in a synodic month to argue that solar tidal dissipation is important in the dynamics of the earth-moon system and that the moment of inertia of the earth cannot have been much larger then than it is now. The tendency of the measurements to remain near 30 days may be a resonance effect.
Journal of Computational Physics | 1991
Richard H. Miller
Journal of Computational Physics | 1971
Richard H. Miller
Archive | 1994
Richard H. Miller
Archive | 1996
Bruce F. Smith; Richard Allan Gerber; T. Y. Steiman-Cameron; Richard H. Miller; Jeff C. Cuzzi