Anne M. Hofmeister

Research Professor of Earth and Planetary Sciences
PhD, California Institute of Technology
research interests:
  • Classical Physics Applied to Astronomy
  • Heat Transfer
  • Dust in Space
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    • Washington University
    • CB 1169
    • One Brookings Drive
    • St. Louis, MO 63130-4899
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    Anne M. Hofmeister's research interests include classical physics applied to astronomy, heat transfer, and dust in space. 

    The drivers of evolutionary behavioron diverse scales are the force of gravity, which brings objects together, and heat transfer from warmer to cooler bodies, which has contrasting effects. Consideringboth processessimultaneously reveals that dark matter as envisioned cannot surround galaxies, seethe paper“Thermodynamic Constraints on the Non-Baryonic Dark Matter Gas Composing Galactic Halos”(https://doi.org/10.3390/galaxies8040077).

    Regarding gravitation, the oblate shape arises from gravitational equilibrium during spin, as was discovered by Newton and Maclaurin some 300 years ago. In astronomy, orbits have been the focus rather than spin. In a collaborative effort with R.E. Criss (EPS) and E.M. Criss (Panasonic Avionics), we have shown that errors affect various properties of gas giants and their satellites since the non-central nature of attraction to the oblate was not previously considered.

    Non-centrality is extremely important to behavior of galaxies, motivating a recent special issue in the journal Galaxies “Debate on the Physics of Galactic Rotation and the Existence of Dark Matter”, summarized here: https://doi.org/10.3390/galaxies8030054, with a video introduction here: https://wustl.app.box.com/s/tgquekywgtpcm5jawu99z78bmhfipnup.

    Our 2019 textbook, Measurements, Mechanisms, and Models of Heat Transport, offers an interdisciplinary approach to the dynamic response of matter to energy input. Using a combination of fundamental principles of physics, recent developments in measuring time-dependent heat conduction, and analytical mathematics, this reference summarizes the relative advantages of currently used methods in heat transfer, and remediates flaws in modern models and their historical precursors. An inelastic kinetic model for gas is provided, which explains differences among mass and heat diffusivities with kinematic viscosity. Implications for condensed matter are covered and supported with copious data.

    The above principles were applied in our 2020 monograph, Heat Transport and Energetics of the Earth and Rocky Planets (https://www.elsevier.com/books/heat-transport-and-energetics-of-the-eart...) with the goal of stimulating thinking beyond the currently popular models of planetary thermal state and evolution. We present a picture of the interior temperatures and of Earth’s evolution that is consistent with observations and physical principles of thermostatics, heat transport, and gravitation. Geotherms for all regions of the Earth are provided. A new explanation for the formation of chondrules and chondritic meteorites addresses the known absence of a heat source sufficient for melting. Mathematic errors invalidating plate cooling models are revealed. Analytical solutions for conductive cooling focus on layers in the continental lithosphere, using new data on andesites and granodiorites.

    Additional Areas of Research

    Heat Transfer

    Thermal conductivity (k) or its close relative thermal diffusivity (D) plays an crucial role anywhere heat is exchanged, such as magmatism, mantle convection and evolution of diverse planetary bodies. Most of the available data on materials comprising planets and meteorites were collected using contact methods and contain systematic and opposing errors due to contact resistance and spurious radiative transfer. The only method which provides accurate and reliable values for semi-transparent materials such as silicates and oxides is laser-flash analysis. Such an apparatus is in operation in the mineral physics program at Washington U. It is the only such facility in geoscience world-wide.

    Because of substantial errors in the measurements, heat transport in insulators has been misunderstood. Some of the work at Washington U. involves basic theoretical physics. The data gathered here are in reasonably good agreement with the damped harmonic oscillator model, which allows extrapolation to the deep Earth. Our best estimates are 5 to 10 times conventional numbers for the core mantle boundary and suggest a very stagnant lower mantle.

    We are undertaking systematic study of D of diverse materials as a function of temperature. One focus is on high pressure phases such as perovskites. Methods for measuring D at pressure are underdevelopment. This program is in collaboration with J. J. Dong (Auburn University) with the goal of improved theory and measurements which will provide robust values to the core-mantle boundary. Applications to mantle convection are being made in collaboration with Dave Yuen (U. Minnesota). Application has been made to revising the global heat flux (with R. E. Criss in this department). We have shown that the current models used to provide this estimate do not conserve rock-mass. An improved model is underdevelopment.

    Another focus is thermal diffusivity of continental crustal materials and their melts, as well as glasses, in collaboration with Alan G. Whittington and Peter Nabelek (U. Missouri, Columbia). Applications are underway to the continental geotherm, understanding thrust belts, and pluton assemblage. A search is underway for a postdoctoral assistant. New graduate students are welcome.

    Newtonian Gravitation

    Current projects involvethe orbit of Mercury and lunar drift, in collaboration with Everett Criss, and spin of the stars, in collaboration with Robert Criss.

    Dust in Space

    Astronomical measurements of infrared spectra show signatures of dust superimposed upon stellar emissions. A first step in understanding the development of protoplanetary nebula is simply identification of the dust that exists in space. To achieve this end, my research group is collecting IR reflectivity spectra and thin film data of about 100 minerals thought to be part of the condensation sequence, or identified in meteorites, and various simple chemical compounds, and glasses. Quantitative analyses of these data provide optical functions and emission spectra, which can be used to infer grain sizes, in addition to chemistry and structure. Application to the stars is made through collaborations with Angela Speck (University of Missouri) and Karly Pitman (PSI; NASA/JPL) Much of the laboratory data were gathered by Erin Keppel, a middle-school teacher in St. Louis, during her summer break. Future plans include low temperature emissions and reflection spectra, and study of organic compounds.