An introductory class on recent groundbreaking findings on dark energy (DESI)

M. Abdul Karim et al. (many authors), DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints, available at https://data.desi.lbl.gov/public/papers/y3/KP.DR2.BAO.pdf.

This is a synthetic introductory class (no expertise assumed!) generated using enTalkenator. Give it a quick listen! This and companion papers were widely reported, including here: https://www.nytimes.com/2025/03/19/science/space/astronomer-desi-dark-energy.html.

Abstract: We present baryon acoustic oscillation (BAO) measurements from more than 14 million galaxies and quasars drawn from the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), based on three years of operation. For cosmology inference, these galaxy measurements are combined with DESI Lyman-α forest BAO results presented in a companion paper. The DR2 BAO results are consistent with DESI DR1 and SDSS, and their distance-redshift relationship matches those from recent compilations of supernovae (SNe) over the same redshift range. The results are well described by a flat ΛCDM model, but the parameters preferred by BAO are in mild, 2.3σ tension with those determined from the cosmic microwave background (CMB), although the DESI results are consistent with the acoustic angular scale θ∗ that is well-measured by Planck. This tension is alleviated by dark energy with a time-evolving equation of state parametrized by w0 and wa, which provides a better fit to the data, with a favored solution in the quadrant with w0 >−1 and wa < 0. This solution is preferred over ΛCDM at 3.1σ for the combination of DESI BAO and CMB data. When also including SNe, the preference for a dynamical dark energy model over ΛCDM ranges from 2.8−4.2σ depending on which SNe sample is used. We present evidence from other data combinations which also favor the same behavior at high significance. From the combination of DESI and CMB we derive 95% upper limits on the sum of neutrino masses, finding mν < 0.064 eV assuming ΛCDM and mν < 0.16 eV in the w0wa model. Unless there is an unknown systematic error associated with one or more datasets, it is clear that ΛCDM is being challenged by the combination of DESI BAO with other measurements and that dynamical dark energy offers a possible solution.

Cohen, “Oligarchy, State, and Cryptopia”

Julie E. Cohen, Oligarchy, State, and Cryptopia.

Solum’s Download of the Week for March 13, 2025. Available on SSRN.

This is a synthetic academic workshop generated using enTalkenator.

Abstract: “Theoretical accounts of power in networked digital environments typically do not give systematic attention to the phenomenon of oligarchy—to extreme concentrations of material wealth deployed to obtain and protect durable personal advantage. The biggest technology platform companies are dominated to a singular extent by a small group of very powerful and extremely wealthy men who have played uniquely influential roles in structuring technological development in particular ways that align with their personal beliefs and who now wield unprecedented informational, sociotechnical, and political power. Developing an account of oligarchy and, more specifically, of tech oligarchy within contemporary political economy therefore has become a project of considerable urgency. This essay undertakes that project.

As I will show, tech oligarchs’ power derives partly from legal entrepreneurship related to corporate governance and partly from the infrastructural character of the functions the largest technology platform firms now perform. It is transnational and multidimensional, producing a wide range of consequences that are impossible for millions (and sometimes billions) around the globe to avoid. And it is personal; tech oligarchs have never been required to trade increased scale for increased accountability.

This account of tech oligarchy has important implications for three large categories of hotly debated issues. First, it sheds new light on the much-remarked inability of nation states to govern giant global technology platform firms effectively using the traditional tools of economic regulation. Second, it illuminates an important difference between the way capitalists approach projects for regulatory capture and the way technology oligarchs approach them. The ordinary capture projects of most interest to tech oligarchs revolve around personal enrichment; the extraordinary experiment that the U.S. is now witnessing, however, also seeks to reconfigure the state and its constituent institutions in ways more amenable to oligarchic direction. Third, it counsels more careful attention to an array of other oligarchic projects—including especially dreams of space colonization and the quest to develop artificial general intelligence—that have struck many observers as fantastical. Through such projects, tech oligarchs are working to dismantle existing forms of social, economic, and political organization and define a human future that they alone determine.”

A brief introductory class on Ongole, Singh, and Wang on loop quantum black holes

Geeth Ongole, Parampreet Singh, and Anzhong Wang, Lessons from gauge fixing and polymerization of loop quantum black holes with a cosmological constant, available at https://arxiv.org/abs/2502.09718.

This is a synthetic introductory class (no expertise assumed!) generated using enTalkenator. Give it a quick listen!

Abstract: Loop quantization of Schwarzschild black holes with a cosmological constant for polymerization parameters which are constant is studied in the effective spacetime description. We show that for the positive cosmological constant there can be an appearance of large quantum effects at small spacetime curvatures. These effects can manifest as an additional black hole horizon. While the central singularity is resolved in all the cases, these limitations demonstrate incompatibility of the Kantowski-Sachs gauge and schemes with fixed polymerization parameters in the presence of a positive cosmological constant. In contrast, the case of a negative cosmological constant is free of such problematic features. Noted limitations are similar to those in the µo scheme for the loop quantization of cosmological models.

Larsen, “Is History Precedent?”

Alli Orr Larsen, Is History Precedent?

Solum’s Download of the Week for March 8, 2025. Available on SSRN.

This is a synthetic academic workshop generated using enTalkenator.

Abstract: “It has been just over two years since the Supreme Court instructed lower courts to evaluate Second Amendment challenges by examining history and tradition.  And it is no secret that the courts have struggled.  This article tackles a phenomenon that is born out of that struggle.  Overwhelmed by the task of evaluating historical claims, lower courts instead are turning to other judges as authorities on history.  They are using what I call in this article, “historical precedents” – meaning language about history from an older decision that the second judge then treats as authority, not as part of the legal rule but as truth of the matter asserted. This practice presents a very interesting puzzle: once the Supreme Court blesses a historical source or a historical narrative, does that conclusion – in and of itself – bind other courts to the same answer about what happened in the past?

The question is more than just an academic head scratcher.  It creates significant practical concerns.  The Supreme Court is not designed to be a factfinding institution, nor are the Justices trained historians.  They can make mistakes, or our understanding of the history can change, and in any event some language that recites historical claims – particularly when appearing in separate opinions – is not contemplated with the kind of spotlight and scrutiny that comes when a legal rule is debated.  These realities make entrenching historical precedents throughout the judicial hierarchy a risky endeavor.

To be sure, lower court judges are in a tight spot when it comes to managing Second Amendment litigation, and this article seeks to help.  I assume a good-faith judge trying to comply with the Supreme Court’s instructions and tempted to clear issues off the docket by citing someone else’s answers to an historical question.  That short-cut is not always appropriate. Not all historical claims are the same, nor were they all similarly thought-through by the first decision-maker.  We must look under the hood, so to speak, before accepting the work and the conclusion as truth.  Ultimately my goal in this article is to draw attention to an unappreciated real-world consequence of the Supreme Court’s turn to history and tradition, and to begin the task of reckoning with it.”

Stone on “Rights, Remedies, and Normative Uncertainty about Justice”

Rebecca Stone, Rights, Remedies, and Normative Uncertainty about Justice.

Solum’s Download of the Week for March 1, 2025. Available on SSRN.

This is a synthetic academic workshop generated using enTalkenator.

Abstract: “I develop and defend a novel account of the private law of remedies according to which it is best understood as facilitating deliberations between the parties about the just outcome of their dispute rather than correcting injustice or righting wrongs. According to my democratic conception, the parties are the ones who ideally ought to resolve moral uncertainty about justice between them by deliberating together in good faith about what justice requires. The law of remedies should therefore often refrain from offering a final judgment about what justice between the parties requires, instead setting and implementing fair default rules and principles in the shadow of which the parties will ideally articulate for themselves a joint vision of justice for their relationship.”

Vaswani et al., “Attention Is All You Need”

An introductory class on the now-famous paper, Attention Is All You Need, by Ashish Vaswani, Llion Jones, Noam Shazeer, Aidan N. Gomez, Niki Parmar, Jakob Uszkoreit, Łukasz Kaiser, and Illia Polosukhin.

This class was generated by enTalkenator using the Introduction template.