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The paper is based on a talk given to celebrate Ørsted's discovery of electromagnetism in 1820. It gives a brief account of Ørsted's life and work, before using the evidence of articles on electricity and magnetism in the Encyclopaedia Britannica to assess understanding of the connection between the two phenomena in the 20 years before Ørsted's discovery, and the immediate reception of it.
This paper takes James David Forbes' Encyclopaedia Britannica entry, Dissertation Sixth, as a lens to examine physics as a cognitive, practical, and social, enterprise. Forbes wrote this survey of eighteenth- and nineteenth-century mathematical and physical sciences, in 1852-6, when British "physics" was at a pivotal point in its history, situated between a discipline identified by its mathematical methods - originating in France - and one identified by its university laboratory institutions. Contemporary encyclopaedias provided a nexus for publishers, the book trade, readers, and men of science, in the formation of physics as a field. Forbes was both a witness, whose account of the progress of physics or natural philosophy can be explored at face value, and an agent, who exploited the opportunity offered by the Encyclopaedia Britannica in the mid nineteenth-century to enrol the broadly educated public, and scientific collective, illuminating the connection between the definition of physics and its forms of social practice. Forbes used the terms "physics" and "natural philosophy" interchangeably. He portrayed the field as progressed by the natural genius of great men, who curated t
We investigate whether the predictions of single-field models of inflation are robust under the introduction of additional scalar degrees of freedom, and whether these extra fields change the potentials for which the data show the strongest preference. We study the situation where an extra light scalar field contributes both to the total curvature perturbations and to the reheating kinematic properties. Ten reheating scenarios are identified, and all necessary formulas allowing a systematic computation of the predictions for this class of models are derived. They are implemented in the public library ASPIC, which contains more than 75 single-field potentials. This paves the way for a forthcoming full Bayesian analysis of the problem. A few representative examples are displayed and discussed.
The current flow of high accuracy astrophysical data, among which are the Cosmic Microwave Background (CMB) measurements by the Planck satellite, offers an unprecedented opportunity to constrain the inflationary theory. This is however a challenging project given the size of the inflationary landscape which contains hundreds of different scenarios. Given that there is currently no observational evidence for primordial non-Gaussianities, isocurvature perturbations or any other non-minimal extension of the inflationary paradigm, a reasonable approach is to consider the simplest models first, namely the slow-roll single field models with minimal kinetic terms. This still leaves us with a very populated landscape, the exploration of which requires new and efficient strategies. It has been customary to tackle this problem by means of approximate model independent methods while a more ambitious alternative is to study the inflationary scenarios one by one. We have developed the publicly available runtime library ASPIC to implement this last approach. The ASPIC code provides all routines needed to quickly derive reheating-consistent observable predictions within this class of scenarios. A
We quantify radial mixing in exoplanet hosts and explore links between birth environment, orbital evolution, planetary architecture, and Galactic habitability. We constructed a homogeneous catalogue by cross-matching the Encyclopaedia of Exoplanetary Systems with Gaia DR3 astrometry and infrared photometry from 2MASS and AllWISE. Stellar orbits were integrated using Galpy. Stellar birth radii were inferred by combining Galactic chemical enrichment models with the generalised additive model introduced in Paper I. Giant-planet hosts preferentially trace inner-Galaxy birth sites, whereas brown-dwarf hosts span a broader, less localised range of radial displacements. Rocky-only systems show smaller radial excursions and less centrally concentrated birth radii, while rocky+giant systems are intermediate, retaining a stronger link to inner-disc birth environments than rocky-only systems. We also find that outward-migrators host more compact outer detected companions than inward-migrators, with non-migrators in between. This trend remains tentative because of heterogeneous detection biases. Giant-planet hosts retain a strong connection to metal-rich inner-Galaxy birth environments, wherea
This paper introduces a dataset of enriched geographic coordinates retrieved from Diderot and d'Alembert's eighteenth-century Encyclopedie. Automatically recovering geographic coordinates from historical texts is a complex task, as they are expressed in a variety of ways and with varying levels of precision. To improve retrieval of coordinates from similar digitized early modern texts, we have created a gold standard dataset, trained models, published the resulting inferred and normalized coordinate data, and experimented applying these models to new texts. From 74,000 total articles in each of the digitized versions of the Encyclopedie from ARTFL and ENCCRE, we examined 15,278 geographical entries, manually identifying 4,798 containing coordinates, and 10,480 with descriptive but non-numerical references. Leveraging our gold standard annotations, we trained transformer-based models to retrieve and normalize coordinates. The pipeline presented here combines a classifier to identify coordinate-bearing entries and a second model for retrieval, tested across encoder-decoder and decoder architectures. Cross-validation yielded an 86% EM score. On an out-of-domain eighteenth-century Trev
Particle cosmology is the branch of science that seeks to understand the birth and evolution of the Universe by applying the principles of particle physics. It brings together the physics of the very small (fundamental particles and forces) with the physics of the very large (the structure and evolution of the cosmos). In many ways, the early Universe acts as a natural laboratory - one far more energetic than any collider we can build - offering unique insights into phenomena that may never be accessible on Earth. Cosmological observations such as the Cosmic Microwave Background, the distribution of galaxies, and the accelerating expansion of the Universe serve as windows into the fundamental laws of nature. At the same time, theoretical developments in particle physics have led to theories, such as inflation, baryogenesis, and Dark Matter, that help explain key features of the cosmos.
This article describes experiments in space which measure charged cosmic ray particles in the range from $10\,\mathrm{GV}$ to $10^5\,\mathrm{GV}$ of magnetic rigidity $p/(Ze)$. In this energy range, cosmic rays are expected to originate from sources in the Milky Way and be confined to our galaxy. Spectra of nuclei and their chemical composition are discussed. The spectrum of antiprotons and the search for heavier anti-nuclei are covered. All spectra and especially those of electrons and positrons are analysed for indications of unconventional particle sources, acceleration or transport mechanisms.
Introduction to the theoretical foundations of gravitational waves: from general relativity to detection and binary system waveforms. Lecture notes prepared for the MaNiTou summer school on gravitational waves. Draft chapter for the CNRS contemporary Encyclopaedia Sciences to be published by ISTE.
Population III (or Pop. III) stars, the first stellar generation built up from metal-free primordial gas, first started to form at redshifts z ~ 30. They formed primarily in small dark matter halos with masses of a few million solar masses. The cooling of the gas in these halos was dominated on all scales by molecular hydrogen. Current theoretical models indicate that Pop. III stars typically formed in small clusters with a logarithmically flat mass function due to widespread fragmentation in the protostellar accretion disks around these primordial stars. Massive Pop. III stars are thought to have played a pivotal role in shaping the early Universe, as their feedback regulates subsequent star formation, although the immediate effects of this feedback remain uncertain. Direct detection of Pop. III stars is challenging, but our chances of detecting at least a few Pop. III supernovae within the next decade are brighter. Indirect approaches based on stellar archaeology or gravitational wave detections offer promising constraints. Current observations suggest that most massive Pop. III stars ended their lives as core-collapse supernovae rather than pair-instability supernovae, offering
We study some representations of symmetric groups arising from a certain ideal in the coordinate ring of affine n-space. Our results give graded and representation-theoretic enhancements of sequence 337 of the Online Encyclopaedia of Integer Sequences, involving a symmetric version of the Bernoulli triangle.
We study the problem of generating interesting integer sequences with a combinatorial interpretation. For this we introduce a two-step approach. In the first step, we generate first-order logic sentences which define some combinatorial objects, e.g., undirected graphs, permutations, matchings etc. In the second step, we use algorithms for lifted first-order model counting to generate integer sequences that count the objects encoded by the first-order logic formulas generated in the first step. For instance, if the first-order sentence defines permutations then the generated integer sequence is the sequence of factorial numbers $n!$. We demonstrate that our approach is able to generate interesting new sequences by showing that a non-negligible fraction of the automatically generated sequences can actually be found in the Online Encyclopaedia of Integer Sequences (OEIS) while generating many other similar sequences which are not present in OEIS and which are potentially interesting. A key technical contribution of our work is the method for generation of first-order logic sentences which is able to drastically prune the space of sentences by discarding large fraction of sentences whi
The dataset focuses on Wikipedia users and contains information about demographic and socioeconomic characteristics of the respondents and their activity on Wikipedia. The data was collected using a questionnaire available online between June and July 2023. The link to the questionnaire was distributed via a banner published in 8 languages on the Wikipedia page. Filling out the questionnaire was voluntary and not incentivised in any way. The survey includes 200 questions about: what people were doing on Wikipedia before clicking the link to the questionnaire; how they use Wikipedia as readers (``professional'' and ``personal'' uses); their opinion on the quality, the thematic coverage, the importance of the encyclopaedia; the making of Wikipedia (how they think it is made, if they have ever contributed and how); their social, sport, artistic and cultural activities, both online and offline; their socio-economic characteristics including political beliefs, and trust propensities. More than 200 000 people opened the questionnaire, 100 332 started to answer, and constitute our dataset, and 10 576 finished it. Among other themes identified by future researchers, the dataset can be usef
Spanning two decades, the Encyclopaedia of DNA Elements (ENCODE) is a collaborative research project that aims to identify all the functional elements in the human and mouse genomes. To best serve the scientific community, all data generated by the consortium is shared through a web-portal (https://www.encodeproject.org/) with no access restrictions. The fourth and final phase of the project added a diverse set of new samples (including those associated with human disease), and a wide range of new assays aimed at detection, characterization and validation of functional genomic elements. The ENCODE data portal hosts results from over 23,000 functional genomics experiments, over 800 functional elements characterization experiments (including in vivo transgenic enhancer assays, reporter assays and CRISPR screens) along with over 60,000 results of computational and integrative analyses (including imputations, predictions and genome annotations). The ENCODE Data Coordination Center (DCC) is responsible for development and maintenance of the data portal, along with the implementation and utilisation of the ENCODE uniform processing pipelines to generate uniformly processed data. Here we
The question of the total measure of invariant tori in analytic, nearly--integrable Hamiltonian systems is considered. In 1985, Arnol'd, Kozlov and Neishtadt, in the Encyclopaedia of Mathematical Sciences \cite{AKN1}, and in subsequent editions, conjectured that in $n=2$ degrees of freedom the measure of the non torus set of general analytic nearly--integrable systems away from critical points is exponentially small with the size $\e$ of the perturbation, and that for $n\ge 3$ the measure is, in general, of order $\e$ (rather than $\sqrt\e$ as predicted by classical KAM Theory). In the case of generic natural Hamiltonian systems, we prove lower bounds on the measure of primary and secondary invariant tori, which are in agreement, up to a logarithmic correction, with the above conjectures. The proof is based on a new {\sl singular} KAM theory, particularly designed to study analytic properties in neighborhoods of the secular separatrices generated by the perturbation at simple resonances.
The infrared problem in quantum electrodynamics consists of intriguing difficulties in scattering theory appearing at large scales and low energies. Although they can be circumvented using ad hoc recipes, such as the inclusive collision cross sections, there have been continuing efforts to reach a conceptually clear and mathematically rigorous understanding. In this article we focus on such developments of the last two decades. We start from the Buchholz-Roberts approach in the setting of algebraic QFT, which is based on the idea that there should be no infrared problems inside the future lightcone. Then we move on to the setting of non-relativistic QED, where insights from Haag-Ruelle scattering theory and the Faddeev-Kulish formalism suggest concrete formulas for the physical electron. Finally, in a setting of perturbative QFT, we outline a recent proposal for an infrared finite scattering matrix, which is also in the spirit of the Faddeev-Kulish approach.
Burning something, (e.g. the proverbial lump of coal, or an encyclopaedia for that matter), in a blackbody furnace leads to an approximately Planck emission spectrum with an average entropy/information transfer of approximately $3.9 \pm 2.5$ bits per emitted photon. This quantitative and qualitative result depends only on the underlying unitarity of the quantum physics of burning, combined with the statistical mechanics of blackbody radiation. The fact that the utterly standard and unitarity preserving process of burning something (in fact, burning anything) nevertheless *has* an associated entropy/information budget, and the quantitative *size* of that entropy/information budget, is a severely under-appreciated feature of standard quantum statistical physics.
The Internet-based encyclopaedia Wikipedia has grown to become one of the most visited web-sites on the Internet. However, critics have questioned the quality of entries, and an empirical study has shown Wikipedia to contain errors in a 2005 sample of science entries. Biased coverage and lack of sources are among the "Wikipedia risks". The present work describes a simple assessment of these aspects by examining the outbound links from Wikipedia articles to articles in scientific journals with a comparison against journal statistics from Journal Citation Reports such as impact factors. The results show an increasing use of structured citation markup and good agreement with the citation pattern seen in the scientific literature though with a slight tendency to cite articles in high-impact journals such as Nature and Science. These results increase confidence in Wikipedia as an good information organizer for science in general.
Reheating is the the epoch which connects inflation to the subsequent hot Big-Bang phase. Conceptually very important, this era is however observationally poorly known. We show that the current Planck satellite measurements of the Cosmic Microwave Background (CMB) anisotropies constrain the kinematic properties of the reheating era for most of the inflationary models. This result is obtained by deriving the marginalized posterior distributions of the reheating parameter for about 200 models taken in Encyclopaedia Inflationaris. Weighted by the statistical evidence of each model to explain the data, we show that the Planck 2013 measurements induce an average reduction of the posterior-to-prior volume by 40%. Making some additional assumptions on reheating, such as specifying a mean equation of state parameter, or focusing the analysis on peculiar scenarios, can enhance or reduce this constraint. Our study also indicates that the Bayesian evidence of a model can substantially be affected by the reheating properties. The precision of the current CMB data is therefore such that estimating the observational performance of a model now requires to incorporate information about its reheati