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Diffeomorphism invariance is a feature that gets sometimes highlighted as something with profound implications in the physics of spacetime. Moreover, it is often wrongly associated exclusively with General Relativity. The fact that diffeomorphism invariance and general covariance are used interchangeably does not help. Here, we attempt at clarifying these concepts., Comment: 6 pages, 3 figures, informal style

The Bohr and von Neumann views on the measurement process in quantum mechanics have been interpreted for a long time in somewhat controversial terms, often leading to misconceptions. On the basis of some textual analysis, I would like to show that, contrary to a widespread opinion, their views should be taken less inconsistent, and much closer to each other, than usually thought. As a consequence, I claim that Bohr and von Neumann are conceptually on the same side on the issue of the universality of quantum mechanics: hopefully, this might contribute to a more accurate history of the measurement problem in quantum mechanics.

The Many-worlds Interpretation (MWI) of quantum mechanics has captivated physicists and philosophers alike since its inception in the mid-20th century. This paper explores the historical roots, evolution, and implications of the MWI within the context of quantum theory. Beginning with an overview of early developments in quantum mechanics and the emergence of foundational interpretations, we delve into the origins of the MWI through the groundbreaking work of physicist Hugh Everett III. Everett's doctoral thesis proposed a radical solution to the measurement problem, positing the existence of multiple branching universes to account for quantum phenomenon. We trace the evolution of the MWI, examining its refinement and elaboration by subsequent physicists such as John Wheeler. Furthermore, we discuss the MWI's impact on contemporary physics, including its connections to quantum information theory and ongoing experimental tests. By providing a comprehensive analysis of the MWI's historical development and current relevance, this paper offers insights into one of the most provocative interpretations of quantum mechanics and its implications for our understanding of the universe., Comment: The article is currently being peer-reviewed at the journal: European Physical Journal H

The study of the differences detected between the observed and the predicted positions of Uranus taking only the ancient planets into account led to the discovery of planet Neptune in 1846. This event remains one of the best accomplishments ever achieved in the history of Astronomy and Classical Mechanics. In this paper, we study the perturbations in the orbit of Uranus due to Neptune and its effects from a modern numerical point of view of the $N$-body problem. The effects induced by Pluto in the orbit of Neptune, as the historical search for a ninth planet in the Solar System (recently boostered again with the hypothesis of the so-called Planet Nine) back in the days was propelled by some supposed small inconsistencies in the orbit of the ice giants, are also analyzed., Comment: Article is being prepared for submission to Astronomy & Astrophysics

Even though quantum entanglement is today's most essential concept within the new technological era of quantum information processing, we do not only lack a consistent definition of this kernel notion, we are also far from understanding its physical meaning [35]. These failures have lead to many problems when attempting to provide a consistent measure or quantification of entanglement. In fact, the two main lines of contemporary research within the orthodox literature have created mazes where inconsistencies and problems are found everywhere. While the operational-instrumentalist approach has failed to explain how inequalities are able to distinguish the classical from the quantum, the geometrical approach has failed to provide a consistent meaningful account of their entropic measure. Taking distance from orthodoxy, in this work we address the quantification and measure of quantum entanglement by considering a recently presented objective-invariant definition in terms of the coding of intensive relations [21] which allows to escape the widespread relativist account of bases and factorizations [24, 25]. Going beyond the orthodox dualistic reference to "quantum particles" and "clicks" in detectors, we will argue that this new line of research is capable not only to evade the many open problems which appear within the mainstream literature, but is also able to present a consistent and coherent physical understanding of entanglement. The main conclusion of this work is that in quantum mechanics -- contrary to what is generally presupposed -- all operational expressions found within the laboratory are intrinsically entangled., Comment: arXiv admin note: text overlap with arXiv:2404.14891

Today, the Ising model is an archetype describing collective ordering processes. And, as such, it is widely known in physics and far beyond. Less known is the fact that the thesis defended by Ernst Ising 100 years ago (in 1924) contained not only the solution of what we call now the `classical 1D Ising model' but also other problems. Some of these problems, as well as the method of their solution, are the subject of this note. In particular, we discuss the combinatorial method Ernst Ising used to calculate the partition function for a chain of elementary magnets. In the thermodynamic limit, this method leads to the result that the partition function is given by the roots of a certain polynomial. We explicitly show that `Ising's roots' that arise within the combinatorial treatment are also recovered by the eigenvalues of the transfer matrix, a concept that was introduced much later. Moreover, we discuss the generalization of the two-state model to a three-state one presented in Ising's thesis, but not included in his famous paper of 1925 ( \i E. Ising, Z. Physik {\bf 31} (1925) 253}). The latter model can be considered as a forerunner of the now abundant models with many-component order parameters.

If we consider a cat to be an isolated mechanical system governed by T-invariant mechanics, then its ability to land on its feet after being released from rest is incomprehensible. It is more appropriate to treat the cat as a creature that can change its shape in order to accomplish a purpose. Within that framework we can construct a useful and informative of the observed motion. One can learn from this example., Comment: 12 pages, 0 figures

Detlef D\"urr (1951-2021) was a theoretical and mathematical physicist who worked particularly on the foundations of quantum mechanics, electromagnetism, and statistical mechanics. This piece is a rather personal look back at him and his science., Comment: 7 pages LaTeX, no figures

If an asymmetry in time does not arise from the fundamental dynamical laws of physics, it may be found in special boundary conditions. The argument normally goes that since thermodynamic entropy in the past is lower than in the future according to the Second Law of Thermodynamics, then tracing this back to the time around the Big Bang means the universe must have started off in a state of very low thermodynamic entropy: the Thermodynamic Past Hypothesis. In this paper, we consider another boundary condition that plays a similar role, but for the decoherent arrow of time, i.e. the quantum state of the universe is more mixed in the future than in the past. According to what we call the Entanglement Past Hypothesis, the initial quantum state of the universe had very low entanglement entropy. We clarify the content of the Entanglement Past Hypothesis, compare it with the Thermodynamic Past Hypothesis, and identify some challenges and open questions for future research., Comment: 10 pages, no figures

In the foundations of quantum mechanics, the Kolmogorovian Censorship (KC) stipulates that quantum probabilities can be identified with classical, Kolmogorovian probabilities when considering a specified measurement context. Then in any given measurement context it is possible to build a Kolmogorovian probability distribution, or equivalently a hidden variable theory; however this distribution must be matched to the chosen context. In a loophole-free Bell test, the remote random choices of measurements (polarizers orientations) have the purpose to prevent that this matching can be obtained from any relativistically causal transmission between the source and the detectors. Then the matching (required to violate Bell's inequalities) may be obtained either by an instantaneous influence at a distance between the source and the detectors (explicit nonlocality), or by assuming that it is pre-established before the actual experiment takes place (super-determinism). If both influence at a distance and super-determinism are not accepted on physical grounds, a third way is still available, called "predictive incompleteness": it tells that the usual quantum state $\psi$ is incomplete, as long as the measurement context has not been specified. In agreement with the general quantum framework called CSM (Contexts, Systems and Modalities) we argue that predictive incompleteness is the correct quantum way to understand the violation of Bell's inequalities., Comment: 4 pages, no figure

We consider two simple criteria for when a physical theory should be said to be "generally covariant", and we argue that these criteria are not met by Yang-Mills theory, even on geometric formulations of that theory. The reason, we show, is that the bundles encountered in Yang-Mills theory are not natural bundles; instead, they are gauge-natural. We then show how these observations relate to previous arguments about the significance of solder forms in assessing disanalogies between general relativity and Yang-Mills theory. We conclude by suggesting that general covariance is really about functoriality., Comment: 26 pages, no figures

This work explores the hypothesis that subjectively attributed meaning constitutes the phenomenal content of conscious experience. That is, phenomenal content is semantic. This form of subjective meaning manifests as an intrinsic and non-representational character of qualia. Empirically, subjective meaning is ubiquitous in conscious experiences. We point to phenomenological studies that lend evidence to support this. Furthermore, this notion of meaning closely relates to what Frege refers to as "sense", in metaphysics and philosophy of language. It also aligns with Peirce's "interpretant", in semiotics. We discuss how Frege's sense can also be extended to the raw feels of consciousness. Sense and reference both play a role in phenomenal experience. Moreover, within the context of the mind-matter relation, we provide a formalization of subjective meaning associated to one's mental representations. Identifying the precise maps between the physical and mental domains, we argue that syntactic and semantic structures transcend language, and are realized within each of these domains. Formally, meaning is a relational attribute, realized via a map that interprets syntactic structures of a formal system within an appropriate semantic space. The image of this map within the mental domain is what is relevant for experience, and thus comprises the phenomenal content of qualia. We conclude with possible implications this may have for experience-based theories of consciousness., Comment: 28 pages

Realism about quantum theory naturally leads to realism about the quantum state of the universe. It leaves open whether it is a pure state represented by a wave function, or an impure one represented by a density matrix. I characterize and elaborate on Density Matrix Realism, the thesis that the universal quantum state is objective but can be impure. To clarify the thesis, I compare it with Wave Function Realism, explain the conditions under which they are empirically equivalent, consider two generalizations of Density Matrix Realism, and answer some frequently asked questions. I end by highlighting an implication for scientific realism., Comment: 22 pages

An attempt is made to evaluate progress of the Polish astrophysical research of stars and of the inter-stellar medium (ISM) on the basis of scientific paper citations in the ADS database. Rather modest citation levels were observed in the years before the mid-1950's. In the years 1958 - 1973, thanks to the partly opened foreign contacts and to strong support from astronomers of the older generation, work of a number of young, energetic enthusiasts reached the world science levels and formed a strong basis for the well recognized, international successes of the next generations., Comment: Presented on the 100-year anniversary of the Polish Astronomical Society during the meeting in Torun, Poland, Sept.11-16, 2023

The complex relationship between Einstein's second postulate and the Maxwell electromagnetic theory is elucidated. A simple deduction of the main results of the Ignatowski approach to the theory of relativity is given. The peculiar status of the principle of relativity among the Maxwellians is illustrated., Comment: 11 pages

Mikhail Lomonosov (1711-1765) is the eminent Russian polymath and a towering figure of the European Enlightenment. This English translation of his seminal work Discourse on Greater Accuracy of Navigation concludes the series of English translations of nine most significant scientific treatises, all of which Lomonosov himself compiled in the volume titled Lomonosow Opera Academica, intended for dissemination among European Academies., Comment: 45 pages, 28 figures

There is solid consensus among physicists and philosophers that, in gauge field theory, for a quantity to be physically meaningful or real, it must be gauge-invariant. Yet, every ``elementary" field in the Standard Model of particle physics is actually gauge-variant. This has led a number of researchers to insist that new manifestly gauge-invariant approaches must be established. Indeed, in the foundational literature, dissatisfaction with standard methods for reducing gauge symmetries has been expressed: Spontaneous symmetry breaking is deemed conceptually dubious, while gauge fixing suffers the same limitations and is subject to the same criticisms as coordinate choices in General Relativity. An alternative gauge-invariant proposal was recently introduced in the literature, the so-called ``dressing field method" (DFM). It is a mathematically subtle tool, and unfortunately prone to be confused with simple gauge transformations, hence with standard gauge~fixings. As a matter of fact, in the physics literature the two are often conflated, and in the philosophy community some doubts have been raised about whether there is any substantial difference between them. Clarifying this issue is of special significance for anyone interested in both the foundational issues of gauge theories and their invariant formulation. It is thus our objective to establish as precisely as possible the technical and conceptual distinctions between the DFM and gauge fixing.

We propose an extension of the classical dichotomous categorization of research programmes into progress and degeneration according to Lakatos in the form of a neutral third category: the stagnant research programme. First, a critical examination of the primary literature with its often criticized definitional gaps justifies such a category. Through a generic derivation of criteria for stagnant programmes, a clear demarcation from progressive and degenerative ones is achieved. An empirical cross-check is subsequently employed for support: Both a series of examples from fundamental physics and a general analysis of today's research landscape also suggest on an empirical level the need to go beyond the traditional Lakatosian conception. Attributing stagnation is entirely in line with Lakatos' original intentions, which aimed not to hastily discard promising research but to exercise patience until the lifting of certain external constraints potentially enables progress once again.

Mikhail Lomonosov (1711-1765) was the eminent Russian polymath and a towering figure of the European Enlightenment. This English translation of Mikhail Lomonosov seminal work "Oration on the Origin of Light " draws from its original Russian and Latin sources. It is part of a series of English translations of nine most significant scientific treatises, all of which Lomonosov himself compiled in the volume titled Lomonosow Opera Academica, intended for dissemination among European Academies., Comment: 22 pages, 1 figure

Mikhail Lomonosov (1711-1765) was a Russian polymath and one of the giants of the European Enlightenment. This English translation of his seminal work Oration on Benefits of Chemistry continues the series of translations of nine most important scientific works, which were included by Lomonosov himself in the convolute Lomonosow Opera Academica and sent for distribution among scientific Academies in Europe., Comment: 15 pages, 1 figure

This English translation of seminal work of Russian polymath Mikhail Lomonosov. It is derived from its Russian and Latin originals (1757) and continues the series of English translations of Lomonosov nine most important scientific works, which were included by Lomonosov himself in the convolute Lomonosow Opera Academica sent for distribution among Academies in Europe., Comment: 21 pages, 1 figure

We propose our account of the meaning of local symmetries. We argue that the general covariance principle and gauge principle both are principles of democratic epistemic access to the law of physics, leading to ontological insights about the objective nature of spacetime. We further argue that relationality is a core notion of general-relativistic gauge field theory, tacitly encoded by its (active) local symmetries., Comment: 21 pages

The presence of an absorber in one of the paths of an interferometer changes the output statistics of that interferometer in a fundamental manner. Since the individual quantum particles detected at any of the outputs of the interferometer have not been absorbed, any non-trivial effect of the absorber on the distribution of these particles over these paths is a counterfactual effect. Here, we quantify counterfactual effects by evaluating the information about the presence or absence of the absorber obtained from the output statistics, distinguishing between classical and quantum counterfactual effects. We identify the counterfactual gain which quantifies the advantage of quantum counterfactual protocols over classical counterfactual protocols, and show that this counterfactual gain can be separated into two terms: a semi-classical term related to the amplitude blocked by the absorber, and a Kirkwood-Dirac quasiprobability assigning a joint probability to the blocked path and the output port. A negative Kirkwood-Dirac term between a path and an output port indicates that inserting the absorber into that path will have a focussing effect, increasing the probability of particles arriving at that output port, resulting in a significant enhancement of the counterfactual gain. We show that the magnitude of quantum counterfactual effects cannot be explained by a simple removal of the absorbed particles, but originates instead from a well-defined back-action effect caused by the presence of the absorber in one path, on particles in other paths., Comment: 13 pages, 3 figures

Phenomena in gauge theory are often described in the physics literature via a specific choice of gauge. In foundational and philosophical discussions this is often criticized as introducing gauge dependence, and contrasted against (often aspirational) "gauge-invariant" descriptions of the physics. I argue, largely in the context of scalar electrodynamics, that this is misguided, and that descriptions of a physical process within a specific gauge are in fact gauge-invariant descriptions. However, most of them are non-local descriptions of that physics, and I suggest that this ought to be the real objection to such descriptions. I explore the unitary gauge as the exception to this nonlocality and consider its strengths and limitations, as well as (more briefly) its extension beyond scalar electrodynamics., Comment: 19 pages. Updated due to initial typo in title

In orthodox Standard Quantum Mechanics (SQM) bases and factorizations are considered to define quantum states and entanglement in relativistic terms. While the choice of a basis (interpreted as a measurement context) defines a state incompatible to that same state in a different basis, the choice of a factorization (interpreted as the separability of systems into sub-systems) determines wether the same state is entangled or non-entangled. Of course, this perspectival relativism with respect to reference frames and factorizations precludes not only the widespread reference to quantum particles but more generally the possibility of any rational objective account of a state of affairs in general. In turn, this impossibility ends up justifying the instrumentalist (anti-realist) approach that contemporary quantum physics has followed since the establishment of SQM during the 1930s. In contraposition, in this work, taking as a standpoint the logos categorical approach to QM -- basically, Heisenberg's matrix formulation without Dirac's projection postulate -- we provide an invariant account of bases and factorizations which allows us to to build a conceptual-operational bridge between the mathematical formalism and quantum phenomena. In this context we are able to address the set of equivalence relations which allows us to determine what is actually the same in different bases and factorizations., Comment: 19 pages

In previous work with Ken Wharton, it was proposed that Bell correlations are a special sort of selection artefact, explained by a combination of (i) collider bias and (ii) a boundary constraint on the collider variable. This requires no direct causal influence outside lightcones, and may hence offer a new way to reconcile Bell nonlocality and relativity. This piece outlines a new argument for the proposal. It explains how it is valid for a special class of ('W-shaped') Bell experiments involving delayed-choice entanglement swapping, and argues that it can be extended to the general ('V-shaped') case., Comment: 17 pages, 5 figures; this version adds a new title, some missing bibliographical information, and a few minor tweaks

I show that frequentism, as an explanation of probability in classical statistical mechanics, can be extended in a natural way to a decoherent quantum history space, the analogue of a classical phase space. The result is a form of finite frequentism, in which the Gibbs concept of an infinite ensemble of gases is replaced by the quantum state expressed as a superposition of a finite number of decohering microstates. It is a form of finite and actual (as opposed to hypothetical) frequentism insofar as all the microstates exist, even though they may differ macroscopically, in keeping with the decoherence-based Everett interpretation of quantum mechanics., Comment: 29 pages, 4 figures

We discuss the challenges that the standard (Humean and non-Humean) accounts of laws face within the framework of quantum gravity where space and time may not be fundamental. This paper identifies core (meta)physical features that cut across a number of quantum gravity approaches and formalisms and that provide seeds for articulating updated conceptions that could account for QG laws not involving any spatio-temporal notions. To this aim, we will in particular highlight the constitutive roles of quantum entanglement, quantum transition amplitudes and quantum causal histories. These features also stress the fruitful overlap between quantum gravity and quantum information theory., Comment: 19 pages, 5 figures

In spring 1949 about 70 physicists from eight countries met in Florence to discuss recent trends in statistical mechanics. This scientific gathering, co-organized by the Commission on Thermodynamics and Statistical Mechanics of the International Union of Pure and Applied Physics (IUPAP) and the Italian Physical Society (SIF), initiated a tradition of IUPAP-sponsored international conferences on statistical mechanics that lasts to this day. In 1977, when this conference series took the name of StatPhys, the foundational role of the Florence conference was recognized by retrospectively naming it StatPhys1. This paper examines the dual scientific and social significance of the conference, situating it in the broader contexts of the post-World War II reconstruction in Italian physics and of the revitalization of the international science organization. Through an analysis of IUPAP archives and Italian records, we illustrate how the event's success hinged on the aligned objectives of its organizers. Internationally, it was instrumental in defining the scientific and organizational foundations for the activities of IUPAP commissions during a critical phase of IUPAP's history, when the Union was resurging on the international stage post-interwar period inactivity. Nationally, the conference served as a cornerstone in SIF's strategy to re-establish Italian physics' international stature and to aid the domestic revitalization of physics through the internationalization of its activities, notably of its flagship journal, \textit{Il Nuovo Cimento}. This analysis not only sheds light on the conference's impact but also informs recent discussions in the history of science about the multiple roles of international scientific conferences., Comment: 40 pages, 5 figures, 2 tables. Corrected two important misprints

Science is about facts and truth. Yet sometimes the truth and facts are not obvious. For example, in the field of MRI (Magnetic Resonance Imaging), there has been a long-lasting debate about who were the major contributors in its development. Particularly, there was a strong dispute between the followers of two scientists, R. Damadian and P. Lauterbur. In this review, we carefully trace the major developments in the use of NMR for cancer detection starting almost 50 years ago. The research records show that the truth was beyond the claims of either research camps. The development of NMR for cancer detection involved multiple research groups, who made critical contributions at different junctures., Comment: 13 pages, 4 figures, 4 tables; This work was reported in the 2024 APS March Meeting held at Minneapolis as an invited talk given in Session S43: Physics, History, and Future of MRI

Among the various attempts to formulate a theory of quantum gravity, a class of approaches suggests that spacetime, as modeled by general relativity, is destined to fade away. A major issue becomes then to identify which structures may inhabit the more fundamental, non-spatiotemporal environment, as well as to explain the relationship with the higher-level spatiotemporal physics. Recently, it has been suggested that a certain understanding of functionalism is the proper tool to suitably account for the recovery of spacetime. Here the viability and usefulness of such a conceptual strategy is explored, by looking at the various levels of spacetime emergence a theory of quantum gravity is expected to deal with. Our conclusion will be that, while its viability is clear also in a quantum gravity context, the import of spacetime functionalism remains rather unsettled., Comment: 20 pages

In general relativity, the strong equivalence principle is underpinned by a geometrical interpretation of fields on spacetime: all fields and bodies probe the same geometry. This geometric interpretation implies that the parallel transport of all spacetime tensors and spinors is dictated by a single affine connection. Can something similar be said about gauge theory? Agreed, in gauge theory different symmetry groups rule the interactions of different types of charges, so we cannot expect to find the same kind of universality found in the gravitational case. Nonetheless, the parallel transport of all the fields that are charged under the same symmetry group is dictated by a single 'gauge connection', and they all transform jointly under a gauge transformation. Is this kind of 'restricted universality' as geometrically underpinned as in general relativity? Here I argue that it is. The key difference is that the gauge geometry concerns 'internal', as opposed to 'external', spaces. The gauge symmetry of the standard model is thus understood as merely the automorphism group of an internal geometric structure -- $C^3\otimes C^2\otimes C^1$ endowed with an orientation and canonical inner product -- in the same way as spacetime symmetries (such as Poincare transformations), are understood as the automorphism group of an external geometric structure (respectively, a Minkowski metric). And the Ehresmann connection can then be understood as determining parallelism for this internal geometry., Comment: 27 pages, 3 page appendix, 2 figures. arXiv admin note: text overlap with arXiv:1411.3281 by other authors

Stephen Hawking's derivation of Hawking radiation relied on one particular spacetime model, that of a star collapsing into a black hole which then remains in existence forever. He then argued that Hawking radiation implies this model should be thrown away in favour of a different model, that of an evaporating black hole. This aspect of Hawking's argument is an example of an idealization that is pervasive in the literature on black hole thermodynamics, but which has not yet been widely discussed by philosophers. The aim of this paper is to clarify the nature of Hawking's idealization, and to show a sense in which it leads to a paradox. After identifying this idealization paradox in classic derivations of Hawking radiation, I go on to show how various research programmes in black hole thermodynamics can be viewed as possible resolutions to the paradox. I give an initial analysis of the prospects for success of these various resolutions, and show how they shed light on both the philosophical foundations of both Hawking radiation on the nature of idealizations in physics., Comment: 29 pages, 7 figures, preprint (under review)

We explain how the disparate kinematics of quantum mechanics (finite-dimensional Hilbert space of QM) and special relativity (Minkowski spacetime from the Lorentz transformations of SR) can both be based on one principle (relativity principle). This is made possible by the axiomatic reconstruction of QM via information-theoretic principles, which has successfully recast QM as a principle theory a la SR. That is, in the quantum reconstruction program (QRP) and SR, the formalisms (Hilbert space and Lorentz transformations, respectively) are derived from empirically discovered facts (Information Invariance & Continuity and light postulate, respectively), so QM and SR are "principle theories" as defined by Einstein. While SR has a compelling fundamental principle to justify its empirically discovered fact (relativity principle), QRP has not produced a compelling fundamental principle or causal mechanism to account for its empirically discovered fact. To unify these disparate kinematics, we show how the relativity principle ("no preferred reference frame" NPRF) can also be used to justify Information Invariance & Continuity. We do this by showing that when QRP's operational notion of measurement is spatialized, Information Invariance & Continuity entails the empirically discovered fact that everyone measures the same value for Planck's constant h, regardless of their relative spatial orientations or locations (Planck postulate). Since Poincare transformations relate inertial reference frames via spatial rotations and translations as well as boosts, the relativity principle justifies the Planck postulate just like it justifies the light postulate. Essentially, NPRF + c is an adynamical global constraint over the spacetime configuration of worldtubes for bodily objects while NPRF + h is an adynamical global constraint over the distribution of quanta among those bodily objects., Comment: 45 pages, 17 figures

This article, the third in a series about the Russian scientist Mikhail Lomonosov (1711-1765), covers the first decade of his research at the St. Petersburg Academy of Sciences, from his return from an educational his trip abroad in 1741, to the mid-1750s. Lomonosov's major focus was on the establishment of the first Russian laboratory used to introduce modern experimental chemistry and physics methods both to original research and education. The lab supported studies of the physics of colors, chemistry and physics of glasses and training of the Academy students. This article describes how Lomonosov, first an Adjunct Professor and then as a young Professor, fought to create the chemistry lab, and then to establish a broad program of experiments and tests there. The construction of laboratories to be used not just for research but also education only became widespread in the early 19th century, but Lomonosov's laboratory had a significant impact on the early development of the Academy and on Russian science., Comment: 32 pages, 6 Figs; submitted for publication in "Physics in Perspective"

I present and defend a new ontology for quantum theories (or "interpretations" of quantum theory) called Generative Quantum Theory (GQT). GQT postulates different sets of features, and the combination of these different features can help generate different quantum theories. Furthermore, this ontology makes quantum indeterminacy and determinacy play an important explanatory role in accounting for when quantum systems whose values of their properties are indeterminate become determinate. The process via which determinate values arise varies between the different quantum theories. Moreover, quantum states represent quantum properties and structures that give rise to determinacy, and each quantum theory specifies a structure with certain features. I will focus on the following quantum theories: GRW, the Many-Worlds Interpretation, single-world relationalist theories such as Relational Quantum Mechanics, Bohmian Mechanics, hybrid classical-quantum theories, and Environmental Determinacy-based (EnD) Quantum Theory. I will argue that GQT should be taken seriously because it provides a series of important benefits that current widely discussed ontologies lack, namely, wavefunction realism and primitive ontology, without some of their costs. For instance, it helps generate quantum theories that are clearly compatible with relativistic causality, such as EnD Quantum Theory. Also, GQT has the benefit of providing new ways to compare and evaluate quantum theories, which may lead to philosophical and scientific progress on these issues., Comment: Several improvements to the previous version

Even though many of the experiments leading to the standard model of particle physics were done at large accelerator laboratories in the US and at CERN[1] many exciting developments happened in smaller national facilities all over the world. In this report we highlight the history of accelerator facilities in Sweden which was home to the highest-energy cyclotron in Europe for some time in the early 1950s. [1] For a brief history of this story see: V. Ziemann, Beams -- the Story of Particle Accelerators and the Science they Discover, Copernicus books, Springer 2024., Comment: 10 pages

The simulation hypothesis has recently excited renewed interest, especially in the physics and philosophy communities. However, the hypothesis specifically concerns {computers} that simulate physical universes, which means that to properly investigate it we need to couple computer science theory with physics. Here I do this by exploiting the physical Church-Turing thesis. This allows me to introduce a preliminary investigation of some of the computer science theoretic aspects of the simulation hypothesis. In particular, building on Kleene's second recursion theorem, I prove that it is mathematically possible for us to be in a simulation that is being run on a computer \textit{by us}. In such a case, there would be two identical instances of us; the question of which of those is ``really us'' is meaningless. I also show how Rice's theorem provides some interesting impossibility results concerning simulation and self-simulation; briefly describe the philosophical implications of fully homomorphic encryption for (self-)simulation; briefly investigate the graphical structure of universes simulating universes simulating universes, among other issues. I end by describing some of the possible avenues for future research that this preliminary investigation reveals., Comment: 44 pages of text, 5 pages of references, 10 pages of appendices

We propose a distinction between two different concepts of time that play a role in physics: geometric time and creative time. The former is the time of deterministic physics and merely parametrizes a given evolution. The latter is instead characterized by real change, i.e. novel information that gets created when a non-necessary event becomes determined in a fundamentally indeterministic physics. This allows us to give a naturalistic characterization of the present as the moment that separates the potential future from the determined past. We discuss how these two concepts find natural applications in classical and intuitionistic mathematics, respectively, and in classical and multivalued tensed logic, as well as how they relate to the well-known A- and B-theories in the philosophy of time., Comment: 10 pages, 2 figures

In this note, we discuss a historical point regarding Schr\"odinger's discovery of the famous quantum wave equation in 1926 following de Broglie's fundamental works published in 1923-1925 regarding the introduction of matter waves. Drawing on the work of historians and personal analysis, we show that de Broglie was very close to the discovery of the Schr\"odinger equation (at least for the stationary one-electron problem)., Comment: submitted for a special issue of the Annals of the Foundation Louis de Broglie

In the Occhialini-Dilworth Archives of the University of Milan are preserved four typescripts by E. Amaldi, dealing with F.G. Houtermans, German physicist, who fled to the USSR to escape the Nazis. During a Stalinist purge he was arrested. The typescripts were sent to the two Milanese physicists so that they might give a judgement. G.S. Occhialini and C. Dilworth, in fact, had personally met Houtermans in 1934 and in 1950. The scenario is that of the role of nuclear physicists during the WW2. The exchange of letters between Amaldi and the two Milanese physicists will be analysed in order to identify possible influences on Amaldi. I will highlight Dilworth's contribution, which found room in a chapter of Amaldi's biography of Houtermans.

We consider the angle in mathematics and arrive at a conclusion that there are two concepts on the issue. One is a descriptive geometrical one, while the other is from functional analysis. They are somewhat different, allow for different options, and both are legitimate and in use. Their difference may cause certain confusions. While the `geometrical angle' allows for different choice of units, the `functional angle' is a purely dimensionless one, being related to the angle in radians. We consider possible options to resolve the problem as it concerns the units.

The late eighteenth and early nineteenth centuries have long been considered as a formative period for modern Irish political traditions such as nationalism, republicanism and unionism. For Europe it was the time of a turn over in science moving from observation to experiment and from speculation to fact. Richard Kirwan was a well known natural philosopher in Europe and a respected man of science in his time. Throughout all the wars, he was connected with his colleagues in a network reaching across Europe and even to America. Using a few examples, this article is intended to provide an insight how the network worked in a time that was marked by political conflicts and revolutionary events in both science and social life.

Semantic Information Theory (SIT) offers a new approach to evaluating the information architecture of complex systems. In this study we describe the steps required to {\it operationalize} SIT via its application to dynamical problems. Our road map has four steps: (1) separating the dynamical system into agent-environment sub-systems; (2) choosing an appropriate coarse graining and quantifying correlations; (3) identifying a measure of viability; (4) implementing a scrambling protocol and measuring the semantic content. We apply the road map to a model inspired by the neural dynamics of epileptic seizures whereby an agent (a control process) attempts to maintain an environment (a base process) in a desynchronized state. The synchronization dynamics is studied through the well-known Kuramoto model of phase synchronization. Our application of SIT to this problem reveals new features of both semantic information and the Kuramoto model. For the latter we find articulating the correlational structure for agent and environment(the oscillators), allows us to cast the model in in a novel computational (information theoretic) perspective, where the agent-environment dynamics can be thought of as analyzing a communication channel. For the former we find that all the information in our system is semantic. This is in contrast to previous SIT studies of foragers in which semantic thresholds where seen above which no further semantic content was obtained., Comment: 14 pages, 3 appendices, 5 figures

An English (2024) translation by P. Marquet of 3 German papers about "Die Quantenhypothese f\"ur Molekeln mit mehreren Freiheitsgraden (The quantum hypothesis for molecules with multiple degrees of freedom)" and "Bemerkung \"uber die Entropiekonstante zweiatomiger Gase (Remarks on the entropy constant of diatomic gases)" by Max Planck (1915,a,b,c), Comment: 56 pages, 2 Figures

This is an English (annotated) translation of the German paper by Max Planck (1916) "On the absolute entropy of monatomic bodies" (\"Uber die absolute Entropie einatomiger K\"orper)., Comment: 16 pages

The Milky Way's name and role in ancient Egyptian culture remain unclear. One suggestion is that the Milky Way may have been a celestial depiction of the sky goddess Nut. In this work, I test this association using an interdisciplinary approach. In the first part of this paper, I combine astronomical simulations of the ancient Egyptian night sky with primary Egyptian sources to map the goddess Nut onto the Milky Way. With her head and groin firmly associated by primary texts with the western and eastern horizons, respectively, I argue that the summer and winter orientations of the Milky Way could be construed as figurative markers of Nut's torso (or backbone) and her arms, respectively. In the second part of this paper, I situate Nut within the global, multicultural mythology of the Milky Way. Specifically, I show that Nut's roles in the afterlife and the autumn bird migration are consistent with similar roles attributed to the Milky Way by other cultures. Finally, I show that Nut's identification with the Milky Way may even have echoes in contemporary African conceptions of the Galaxy., Comment: 18 pages, 7 figures, preprint of paper published in Journal of Astronomical History and Heritage

After Galileo's publication of the Sidereus Nuncius in 1610, Giovanni Battista Agucchi obtained in 1611 an estimate of the orbital periods of the Galilean satellites of Jupiter using the figures published in the book. The article shows how to repeat these measurements in a teaching context for high school students., Comment: 6 pages, in Italian language, 4 figures

We explore the notion of events at the intersection between quantum physics and gravity, inspired by recent research on superpositions of semiclassical spacetimes. By going through various experiments and thought experiments -- from a decaying atom, to the double-slit experiment, to the quantum switch -- we analyse which properties can and cannot be used to define events in such non-classical contexts. Our findings suggest an operational, context-dependent definition of events which emphasises that their properties can be accessed without destroying or altering observed phenomena. We discuss the implications of this understanding of events for indefinite causal order as well as the non-absoluteness of events in the Wigner's friend thought experiment. These findings provide a first step for developing a notion of event in quantum spacetime., Comment: 6 pages, 1 figure. Essay written for the Gravity Research Foundation 2024 Awards for Essays on Gravitation

The hierarchy problem of the Higgs mass, the violation of the autonomy of far-distant energy scales, is identified as a pseudo-problem. The pseudo-problem is based on the dogmatic adherence to the methodology of effective theories, for which there is no justification when dealing with presumably fundamental phenomena such as the Higgs mechanism. In view of further breaches of autonomy of scales in fundamental principles outside particle physics, the hierarchy problem is instead reinterpreted as an indication of the fundamental ontological status of the Higgs boson. Selective Realism justifies this attribution within the effective theories of the standard model of particle physics. Moreover, a model of changes in aesthetic canons provides an explanation for the existing dogmatism regarding effective theories.