Lenardic, Adrian2020-04-272020-04-272020-052020-04-23May 2020Seales, Johnny. "Uncertainty and Hypothesis Testing in Planetary Thermal History Models." (2020) Diss., Rice University. <a href="https://hdl.handle.net/1911/108401">https://hdl.handle.net/1911/108401</a>.https://hdl.handle.net/1911/108401Plate tectonics convectively cools the Earth at present. Debate remains in defining plate tectonics as a dynamic system. What is the primary resistor to plate motions: plates, mantle viscosity, some mixture of the two? Here I shed some light on this debate. First, I quantify the uncertainties associated with the different hypotheses. Then, I constrain the probability that different thermal paths from each of these hypotheses match Earth's geologic proxy data. Only a single hypothesis is true for Earth. The data, however, cannot tell us which. So, rather than using the most probable hypothesis, we can embrace this uncertainty. Each successful thermal path informs us of how other plate tectonic planetary interiors may have evolved in the past or will evolve in the future. Another question arises from inspecting Earth's thermal history data: what is the convective mechanism for the multi-stage cooling present in some sets of thermal history data? I show that changes in the deep water cycle, namely a switch from a net dehydrating to rehydrating mantle, can act as this mechanism. If this mechanism is true, it may directly influence surface conditions. This may be important for determing whether a planet can maintain liquid water at its surface. Interior processes, then, may play a vital role in determining the inhabitance of a planet. This leaves many searches for life on exoplanets fixated on finding Earth2.0. Depending on the question we ask, however, this may be the wrong approach. I demonstrate that if we cast a broader net in our search for inhabited planets, the increased reward likely outweighs the increased cost.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Mantle ConvectionPlanetary Thermal History ModelingPlanetary HabitabilityUncertainty QuantificationThesis2020-04-27