Michael Williams

Bio: Michael Williams is an academic researcher from University of Glasgow. The author has contributed to research in topics: Physics & Sea ice. The author has an hindex of 80, co-authored 537 publications receiving 24704 citations. Previous affiliations of Michael Williams include University of Sydney & York University.

Stated Preference Approaches for Measuring Passive Use Values: Choice Experiments and Contingent Valuation

Abstract: The measurement of passive use values has become an important issue in environmental economics. In this paper we examine an extension or variant of contingent valuation, the choice experiment, which employs a series of questions with more than two alternatives that are designed to elicit responses that allow the estimation of preferences over attributes of an environmental state. We also combine the information from choice experiments and contingent valuation to test for differences in preferences and error variances arising from the two methods. Our results show that choice experiments have considerable merit in measuring passive use values.

Words, Images, Enemies: Securitization and International Politics

Abstract: The theory of “securitization” developed by the Copenhagen School provides one of the most innovative, productive, and yet controversial avenues of research in contemporary security studies. This article provides an assessment of the foundations of this approach and its limitations, as well as its significance for broader areas of International Relations theory. Locating securitization theory within the context of both classical Realism influenced by Carl Schmitt, and current work on constructivist ethics, it argues that while the Copenhagen School is largely immune from the most common criticisms leveled against it, the increasing impact of televisual communication in security relations provides a fundamental challenge for understanding the processes and institutions involved in securitization, and for the political ethics advocated by the Copenhagen School.

GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run

Abstract: We report on gravitational wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo in the first half of the third observing run (O3a) between 1 April 2019 15:00 UTC and 1 October 2019 15:00. By imposing a false-alarm-rate threshold of two per year in each of the four search pipelines that constitute our search, we present 39 candidate gravitational wave events. At this threshold, we expect a contamination fraction of less than 10%. Of these, 26 candidate events were reported previously in near real-time through GCN Notices and Circulars; 13 are reported here for the first time. The catalog contains events whose sources are black hole binary mergers up to a redshift of ~0.8, as well as events whose components could not be unambiguously identified as black holes or neutron stars. For the latter group, we are unable to determine the nature based on estimates of the component masses and spins from gravitational wave data alone. The range of candidate events which are unambiguously identified as binary black holes (both objects $\geq 3~M_\odot$) is increased compared to GWTC-1, with total masses from $\sim 14~M_\odot$ for GW190924_021846 to $\sim 150~M_\odot$ for GW190521. For the first time, this catalog includes binary systems with significantly asymmetric mass ratios, which had not been observed in data taken before April 2019. We also find that 11 of the 39 events detected since April 2019 have positive effective inspiral spins under our default prior (at 90% credibility), while none exhibit negative effective inspiral spin. Given the increased sensitivity of Advanced LIGO and Advanced Virgo, the detection of 39 candidate events in ~26 weeks of data (~1.5 per week) is consistent with GWTC-1.

GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo During the First Half of the Third Observing Run

Abstract: We report on gravitational wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo in the first half of the third observing run (O3a) between 1 April 2019 15:00 UTC and 1 October 2019 15:00. By imposing a false-alarm-rate threshold of two per year in each of the four search pipelines that constitute our search, we present 39 candidate gravitational wave events. At this threshold, we expect a contamination fraction of less than 10%. Of these, 26 candidate events were reported previously in near real-time through GCN Notices and Circulars; 13 are reported here for the first time. The catalog contains events whose sources are black hole binary mergers up to a redshift of ~0.8, as well as events whose components could not be unambiguously identified as black holes or neutron stars. For the latter group, we are unable to determine the nature based on estimates of the component masses and spins from gravitational wave data alone. The range of candidate events which are unambiguously identified as binary black holes (both objects $\geq 3~M_\odot$) is increased compared to GWTC-1, with total masses from $\sim 14~M_\odot$ for GW190924_021846 to $\sim 150~M_\odot$ for GW190521. For the first time, this catalog includes binary systems with significantly asymmetric mass ratios, which had not been observed in data taken before April 2019. We also find that 11 of the 39 events detected since April 2019 have positive effective inspiral spins under our default prior (at 90% credibility), while none exhibit negative effective inspiral spin. Given the increased sensitivity of Advanced LIGO and Advanced Virgo, the detection of 39 candidate events in ~26 weeks of data (~1.5 per week) is consistent with GWTC-1.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

International Norm Dynamics and Political Change

Abstract: Norms have never been absent from the study of international politics, but the sweeping “ideational turn” in the 1980s and 1990s brought them back as a central theoretical concern in the field. Much theorizing about norms has focused on how they create social structure, standards of appropriateness, and stability in international politics. Recent empirical research on norms, in contrast, has examined their role in creating political change, but change processes have been less well-theorized. We induce from this research a variety of theoretical arguments and testable hypotheses about the role of norms in political change. We argue that norms evolve in a three-stage “life cycle” of emergence, “norm cascades,” and internalization, and that each stage is governed by different motives, mechanisms, and behavioral logics. We also highlight the rational and strategic nature of many social construction processes and argue that theoretical progress will only be made by placing attention on the connections between norms and rationality rather than by opposing the two.