Metastability and instability in holographic gauge theories

We review and extend previous results regarding the stability and thermodynamics of Anti-de Sitter (AdS) spacetime at finite temperature. Using a combination of analytic and numerical techniques, we compute the energy, temperature, and entropy of perfect fluid stars in asymptotically AdS spacetimes. We find that at sufficiently high temperature (in the canonical ensemble) or energy (in the microcanonical ensemble) these configurations develop dynamical instabilities, which presumably lead to the formation of a black hole. We extend our analysis to the case of $AdS \times S$ compactifications stabilized by flux (such as those that arise in supergravity and string theory), and find that the inclusion of the sphere does not substantially alter these results. We then map out the phase structure of these theories in the canonical and microcanonical ensembles, paying attention to inequivalence of these ensembles for global anti-de Sitter space. With a certain scaling limit, the critical temperature can be parametrically lower than the string temperature, so that supergravity is a good description at the instability point. We comment on the implications of this for the unitarity of black holes.Comment: 39 pages, 13 figure

Behavioral Economics and Developmental Science: A New Framework to Support Early Childhood Interventions

Public policies have actively responded to an emergent social and neuroscientific evidence base documenting the benefits of targeting services to children during the earliest period of their development. But problems of low utilization, inconsistent participation, and low retention continue to present themselves as challenges. Although most interventions recognize and address structural and psycho-social barriers to parent’s engagement, few take seriously the decision making roles of parents. Using insights from the behavioral sciences, we revisit assumptions about the presumed behavior of parents in a developmental context. We then describe ways in which this framework informs features of interventions that can be designed to augment the intended impacts of early development, education and care initiatives by improving parent engagement

For the good of society, we need a democratic reformation of finance

The 2007-08 financial crisis showed the limitations of reliance on financial services in running an economy and building a society. Matthew Lawrence argues that we need to move away from a finance based way of doing things, through an ambitious process of ‘definancialisation’, which would see these institutions brought squarely under the purview of democratic control

Ebola and War in the Democratic Republic of Congo: Avoiding Failure and Thinking Ahead

The Ebola epidemic in the Democratic Republic of Congo (DRC) is exceptionally dangerous, occurring within active armed conflict and geopolitical volatility, including a million displaced persons. With 421 cases, 240 deaths, and the numbers increasing, this Ebola outbreak is the second deadliest in history. Recent spread to Butembo, home to 1.2 million people, raised concerns. The DRC, World Health Organization (WHO), and partners are leading a vigorous international response, yet despite deploying an experimental vaccine, cases doubled in October 2018 and many cases had unknown origin. Uncontrolled Ebola outbreaks can expand quickly, as occurred in West Africa in 2014. Averting that outcome in the DRC requires rapid action including a strengthened public health response, security, and community outreach. If violence escalates, it could compromise a fragile response. Yet resources are insufficient. The United States and other countries are not permitting personnel deployment to the epicenter, including from the Centers for Disease Control and Prevention (CDC) and US Agency for International Development (USAID). In this Viewpoint, we review recommendations of experts convened by Georgetown University and listed at the end of this article. The United States and international community should launch high-level political mobilization, with diplomatic, human, and economic resources. It is critical to recognize that future health crises will occur in fragile, insecure settings. To prepare, the international community needs long-term planning and enhanced capacities to improve the safety and effectiveness of epidemic response operations

Day One

Reflections on first day of CPE residency

Large Field Inflation and Gravitational Entropy

Large field inflation can be sensitive to perturbative and nonperturbative quantum corrections that spoil slow roll. A large number $N$ of light species in the theory, which occur in many string constructions, can amplify these problems. One might even worry that in a de Sitter background, light species will lead to a violation of the covariant entropy bound at large $N$. If so, requiring the validity of the covariant entropy bound could limit the number of light species and their couplings, which in turn could severely constrain axion-driven inflation. Here we show that there is no such problem when we correctly renormalize models with many light species, taking the {\it physical} Planck scale to be $M^2_{pl} \gtrsim N {\cal M}_{UV}^2$, where ${\cal M}_{UV}$ is the cutoff for the QFT coupled to semiclassical quantum gravity. The number of light species then cancels out of the gravitational entropy of de Sitter or near-de Sitter backgrounds at leading order. Working in detail with $N$ scalar fields in de Sitter space, renormalized to one loop order, we show that the gravitational entropy automatically obeys the covariant entropy bound. Furthermore, while the axion decay constant is a strong coupling scale for the axion dynamics, we show that it is {\it not} in general the cutoff of 4d semiclassical gravity. After renormalizing the two point function of the inflaton, we note that it is also controlled by scales much below the cutoff. We revisit $N$-flation and KKLT-type compactifications in this light, and show that they are perfectly consistent with the covariant entropy bound. Thus, while quantum gravity might yet spoil large field inflation, holographic considerations in the semiclassical theory do not obstruct it.Comment: 25 pages including references and title page, 18 pages of text. v2: References added, corrected argument at end of Sec. 2.3, additional minor corrections. v3: additional references adde

Public knowledge about polar regions increases while concerns remain unchanged

The authors of this brief conduct the first comparative analysis of the polar questions that were part of the National Opinion Research Center\u27s 2006 and 2010 General Social Survey. Developed by scientists at the National Science Foundation\u27s Office of Polar Programs, these questions covered topics such as climate change, melting ice and rising sea levels, and species extinction. The authors report that the public\u27s knowledge about the north and south polar regions significantly improved between 2006 and 2010--before and after the International Polar Year. In addition, respondents who know more about science in general, and polar facts specifically, tend to be more concerned about polar changes. More knowledgeable respondents also tend to favor reserving the Antarctic for science, rather than opening it for commercial development

Evolving relativistic fluid spacetimes using pseudospectral methods and finite differencing

We present a new code for solving the coupled Einstein-hydrodynamics equations to evolve relativistic, self-gravitating fluids. The Einstein field equations are solved on one grid using pseudospectral methods, while the fluids are evolved on another grid by finite differencing. We discuss implementation details, such as the communication between the grids and the treatment of stellar surfaces, and present code tests.Comment: To appear in the Proceedings of the Eleventh Marcel Grossmann Meetin