arXiv subjects

Edward D. Lee

Publications and source records attributed to Edward D. Lee.

21 records · Page 2Linked to original sources

arXiv2018

Strong consensus on US Supreme Court spans a century

The US Supreme Court throughout the 20th century has been characterized as being divided between liberals and conservatives, suggesting that justices with similar ideologies would have voted similarly had they overlapped in tenure. What if they had? I build an empirical, quantitative model of this counterfactual hypothesis using pairwise maximum entropy. I infer how 36 justices from 1946-2016 would have all voted on a Super Supreme Court. The model is strikingly consistent with a standard voting model from political science despite using $10^5$ less parameters and fitting the observed statistics better. As with historical courts, the Super Court is dominated by consensus. The rate at which consensus decays as more justices are included is extremely slow, nearly 100 years, and indicates that the modern Supreme Court is an extremely stable institution. Beyond consensus, I discover a rich structure of dissenting blocs that are distributed along a heavy-tailed Zipf's law. The heavy tail means that dominant dissenting modes fail to capture the entire spectrum of dissent. Thus, I find that Supreme Court voting over time is not low-dimensional despite implications to the contrary in historical analysis of Supreme Court voting. Although it has been long presumed that strong higher order correlations are induced by features of the cases, the institution, and the justices, I show that such complexity can be expressed in a minimal model relying only on pairwise correlations. From the perspective of model selection, this minimal model may generalize better and thus be useful for prediction of Supreme Court voting over time.

physics.soc-ph↗

arXiv2016

Deformation of crystals: Connections with statistical physics

We give a bird's-eye view of the plastic deformation of crystals aimed at the statistical physics community, and a broad introduction into the statistical theories of forced rigid systems aimed at the plasticity community. Memory effects in magnets, spin glasses, charge density waves, and dilute colloidal suspensions are discussed in relation to the onset of plastic yielding in crystals. Dislocation avalanches and complex dislocation tangles are discussed via a brief introduction to the renormalization group and scaling. Analogies to emergent scale invariance in fracture, jamming, coarsening, and a variety of depinning transitions are explored. Dislocation dynamics in crystals challenges non equilibrium statistical physics. Statistical physics provides both cautionary tales of subtle memory effects in nonequilibrium systems, and systematic tools designed to address complex scale-invariant behavior on multiple length and time scales.

cond-mat.mtrl-sci↗

arXiv2013

Statistical mechanics of the US Supreme Court

We build simple models for the distribution of voting patterns in a group, using the Supreme Court of the United States as an example. The least structured, or maximum entropy, model that is consistent with the observed pairwise correlations among justices' votes is equivalent to an Ising spin glass. While all correlations (perhaps surprisingly) are positive, the effective pairwise interactions in the spin glass model have both signs, recovering some of our intuition that justices on opposite sides of the ideological spectrum should have a negative influence on one another. Despite the competing interactions, a strong tendency toward unanimity emerges from the model, and this agrees quantitatively with the data. The model shows that voting patterns are organized in a relatively simple "energy landscape," correctly predicts the extent to which each justice is correlated with the majority, and gives us a measure of the influence that justices exert on one another. These results suggest that simple models, grounded in statistical physics, can capture essential features of collective decision making quantitatively, even in a complex political context.

physics.soc-ph↗