DE / EN
2024/2025
Bonn History and Philosophy of Physics Research Seminar (Winter)
Time & Place: Tuesdays from 14:15 to 15:45 CEST.
Almost all sessions can be attended via Zoom; the sessions that are indicated as 'hybrid' below may also be attended in person, in the Institute of Philosophy (Heinrich-von-Kleist-Str 22-28, 53113 Bonn) in the Logic Library (2nd Floor). Zoom-links and weekly reminders are announced via [email protected]. Subscribing to this list is possible
a) here,
b) by sending an empty email to [email protected],
or c) by contacting [email protected]
Conveners: Prof. Dr. Dennis Lehmkuhl, Dr. Bernadette Lessel & Nurida Boddenberg
Almost all sessions can be attended via Zoom; the sessions that are indicated as 'hybrid' below may also be attended in person, in the Institute of Philosophy (Heinrich-von-Kleist-Str 22-28, 53113 Bonn) in the Logic Library (2nd Floor). Zoom-links and weekly reminders are announced via [email protected]. Subscribing to this list is possible
a) here,
b) by sending an empty email to [email protected],
or c) by contacting [email protected]
Conveners: Prof. Dr. Dennis Lehmkuhl, Dr. Bernadette Lessel & Nurida Boddenberg
October 15th, 2024 - Jos Uffink
hybrid (in-person speaker)
Jos Uffink (University of Minnesota)
Title: The problem of irreversibility and the quantum Boltzmann equation.
Abstract: I will review Boltzmann’s (1872) derivation of the Boltzmann equation in classical gas theory, and its problems. I will then discuss more recent approaches to obtain a quantum Boltzmann equation in the quantum theory of condensed matter by Gordon Baym and more recently by David Snoke. I will argue that the problems encountered in derivations of the quantum version of the Boltzmann equation are even worse than for its classical counterpart.
Jos Uffink (University of Minnesota)
Title: The problem of irreversibility and the quantum Boltzmann equation.
Abstract: I will review Boltzmann’s (1872) derivation of the Boltzmann equation in classical gas theory, and its problems. I will then discuss more recent approaches to obtain a quantum Boltzmann equation in the quantum theory of condensed matter by Gordon Baym and more recently by David Snoke. I will argue that the problems encountered in derivations of the quantum version of the Boltzmann equation are even worse than for its classical counterpart.
October 22nd, 2024 - Jeremy Butterfield
hybrid (in-person speaker)
Jeremy Butterfield (University of Cambridge)
Title: A philosophical look at quantum reference frames.
Abstract: I will review, from a philosophical perspective, two recent frameworks for using quantum reference frames to describe superpositions of spacetimes. Both use fibre bundles as their basic language. The first (2402.10267) was developed by Kabel, de la Hamette, Brukner, and their co-authors. It addresses the question how to compare spacetime points between non-isomorphic spacetimes in terms of a connection on a fibre bundle whose points are spacetimes; (an idea due to Gomes). This strategy is close in spirit to the philosopher David Lewis’ counterpart theory. The second framework (2406.15838v2) was developed by Vanzella. It is more “concrete”. It models a reference frame at a spacetime point as a tetrad, and so uses the frame bundle. This means it treats the identity of spacetime points between non-isomorphic spacetimes, not in terms of counterparts, but “haecceitistically”. I will end by comparing the frameworks.
Jeremy Butterfield (University of Cambridge)
Title: A philosophical look at quantum reference frames.
Abstract: I will review, from a philosophical perspective, two recent frameworks for using quantum reference frames to describe superpositions of spacetimes. Both use fibre bundles as their basic language. The first (2402.10267) was developed by Kabel, de la Hamette, Brukner, and their co-authors. It addresses the question how to compare spacetime points between non-isomorphic spacetimes in terms of a connection on a fibre bundle whose points are spacetimes; (an idea due to Gomes). This strategy is close in spirit to the philosopher David Lewis’ counterpart theory. The second framework (2406.15838v2) was developed by Vanzella. It is more “concrete”. It models a reference frame at a spacetime point as a tetrad, and so uses the frame bundle. This means it treats the identity of spacetime points between non-isomorphic spacetimes, not in terms of counterparts, but “haecceitistically”. I will end by comparing the frameworks.
October 29th, 2024 - Gal Ben-Porath
hybrid (in person speaker)
Gal Ben-Porath (University of Bonn)
Title: The kinematics of indeterminism.
Abstract: Discussions of determinism and indeterminism of physical theories usually focus on properties of dynamical laws (e.g.,: uniqueness of solution). This is perfectly adequate in all the usual cases. However, when considering speculative models that seek to introduce fundamental indeterminism into physics, such discussions are unsatisfying. The unusual ontological roles attributed to indeterministic changes by the authors of such models, require them to have unusual kinematical features. I will examine these desired roles and point to their problematic nature. I will then suggest recognizing the occurrence of jump discontinuities as the distinguishing feature of indeterministic kinematics and explore some consequences of such a recognition.
Gal Ben-Porath (University of Bonn)
Title: The kinematics of indeterminism.
Abstract: Discussions of determinism and indeterminism of physical theories usually focus on properties of dynamical laws (e.g.,: uniqueness of solution). This is perfectly adequate in all the usual cases. However, when considering speculative models that seek to introduce fundamental indeterminism into physics, such discussions are unsatisfying. The unusual ontological roles attributed to indeterministic changes by the authors of such models, require them to have unusual kinematical features. I will examine these desired roles and point to their problematic nature. I will then suggest recognizing the occurrence of jump discontinuities as the distinguishing feature of indeterministic kinematics and explore some consequences of such a recognition.
November 5th, 2024 - Bernadette Lessel
hybrid (in person speaker)
Bernadette Lessel (University of Bonn)
Title: Louis de Broglie and the five dimensions: how unified field theory was employed to save the particle.
Abstract: Louis de Broglie is most prominently known for his doctoral thesis from 1924 in which he introduced the notion of material waves. But also for belonging to the camp opposing the Copenhagen point of view on qm, denying state space formalism and advocating a realist interpretation of the wave function until he gave it up in the year 1928. This talk investigates the influences of classical field theories, most prominently general relativity and unified field theory, on this reasoning. A central theme for de Broglie is thereby the duality of particle and wave which he saw analogous to the duality of particle and field within classical field theory.
Bernadette Lessel (University of Bonn)
Title: Louis de Broglie and the five dimensions: how unified field theory was employed to save the particle.
Abstract: Louis de Broglie is most prominently known for his doctoral thesis from 1924 in which he introduced the notion of material waves. But also for belonging to the camp opposing the Copenhagen point of view on qm, denying state space formalism and advocating a realist interpretation of the wave function until he gave it up in the year 1928. This talk investigates the influences of classical field theories, most prominently general relativity and unified field theory, on this reasoning. A central theme for de Broglie is thereby the duality of particle and wave which he saw analogous to the duality of particle and field within classical field theory.
November 12th, 2024 - Anastasiia Lazutkina
hybrid (in person speaker)
Anastasiia Lazutkina (University of Wuppertal)
Title: Transformation of testing methods in cosmology: from the 1990s to now.
Abstract: In the late 1980s and early 1990s, observations of galaxies provided important evidence for testing cosmological models, but they gradually lost this role as galaxies revealed complexities that ΛCDM struggled to explain. With the advent of CMB data, the focus shifted to large-scale evidence, which offered cleaner tests for cosmology. In this talk, I will reconstruct how galaxies became too complicated to continue serving as reliable tests of cosmological models.
Anastasiia Lazutkina (University of Wuppertal)
Title: Transformation of testing methods in cosmology: from the 1990s to now.
Abstract: In the late 1980s and early 1990s, observations of galaxies provided important evidence for testing cosmological models, but they gradually lost this role as galaxies revealed complexities that ΛCDM struggled to explain. With the advent of CMB data, the focus shifted to large-scale evidence, which offered cleaner tests for cosmology. In this talk, I will reconstruct how galaxies became too complicated to continue serving as reliable tests of cosmological models.
November 19th, 2024 - Dan Grimmer
hybrid (in-person speaker)
Dan Grimmer (University of Bonn)
Title: Searching for new spacetimes: the ISE method of topological redescription.
Abstract: Beyond Einstein, physicists have continued to find strange things on the front lines of physics: namely spacetime dualities. An illustrative example is the AdS-CFT correspondence. Certain theories which take place in the “bulk” (our usual 3+1 dimensional spacetime) have an equivalent description in terms of a different type of particles/fields living on the boundary (a 2+1 dimensional spacetime). More generally, spacetime dualities are instances where two or more theories—despite being structurally and empirically equivalent—seemingly offer us radically different spatiotemporal descriptions of the world (e.g., with more or less dimensions). This talk will introduce several more examples of spacetime dualities, including the newly discovered M\"{o}bius-Euclid duality. In this duality, a theory about a point-like particle floating around on a Möbius strip can be redescribed as instead being about a different type of particle living on the Euclidean plane, and vice versa.
The fact that our best theories might have multiple possible spacetime framings raises some significant questions about the epistemology and metaphysics of space and time. In particular, it raises questions about how we have come to ascribe certain topological properties to space and time (e.g., their connectedness, continuity, dimensionality, etc.). When multiple options are available, what are our topology selection criteria exactly? And where do these topology selection criteria come from? Are they objective? Or is there some element of conventionality to them? For instance, in a Möbius-Euclid world, could it be that one rational civilization opts for the Möbius representation whereas another opts for the Euclid representation? Our efforts to grapple with these questions would be greatly enhanced if we had more mathematical control over these dualities. To this end, I will present a unified framework (the ISE Method) for dealing with a very wide range of spacetime dualities. Using these new tools, I will argue for the possibility that our topology selection criteria are somewhat conventional. Hence, we should think of space and time as organizational principles which we project onto the world rather than as the spatiotemporal stage upon which the world's drama actually plays out.
Dan Grimmer (University of Bonn)
Title: Searching for new spacetimes: the ISE method of topological redescription.
Abstract: Beyond Einstein, physicists have continued to find strange things on the front lines of physics: namely spacetime dualities. An illustrative example is the AdS-CFT correspondence. Certain theories which take place in the “bulk” (our usual 3+1 dimensional spacetime) have an equivalent description in terms of a different type of particles/fields living on the boundary (a 2+1 dimensional spacetime). More generally, spacetime dualities are instances where two or more theories—despite being structurally and empirically equivalent—seemingly offer us radically different spatiotemporal descriptions of the world (e.g., with more or less dimensions). This talk will introduce several more examples of spacetime dualities, including the newly discovered M\"{o}bius-Euclid duality. In this duality, a theory about a point-like particle floating around on a Möbius strip can be redescribed as instead being about a different type of particle living on the Euclidean plane, and vice versa.
The fact that our best theories might have multiple possible spacetime framings raises some significant questions about the epistemology and metaphysics of space and time. In particular, it raises questions about how we have come to ascribe certain topological properties to space and time (e.g., their connectedness, continuity, dimensionality, etc.). When multiple options are available, what are our topology selection criteria exactly? And where do these topology selection criteria come from? Are they objective? Or is there some element of conventionality to them? For instance, in a Möbius-Euclid world, could it be that one rational civilization opts for the Möbius representation whereas another opts for the Euclid representation? Our efforts to grapple with these questions would be greatly enhanced if we had more mathematical control over these dualities. To this end, I will present a unified framework (the ISE Method) for dealing with a very wide range of spacetime dualities. Using these new tools, I will argue for the possibility that our topology selection criteria are somewhat conventional. Hence, we should think of space and time as organizational principles which we project onto the world rather than as the spatiotemporal stage upon which the world's drama actually plays out.
November 26th, 2024 - David Rowe
hybrid (iAn-person speaker)
David E. Rowe (University of Mainz)
Title: Rotating Models in Relativistic Cosmology, 1950 to 1970
Abstract: This talk will survey work on early models in relativistic cosmology leading to various rotating models from the period 1950 to 1970. Much of this work had direct roots in Mach’s principle, which Einstein first formulated in 1918. These issues were discussed from the perspective of the mid-1990s in the book by Ciufolini and Wheeler, Gravitation and Inertia. Their account takes up some of the cosmological models with rotation that began with the work of Kurt Gödel. Both Gödel and Abraham Taub saw their global solutions of Einstein’s equations as anti-Machian, in the sense that these rotating models were theoretically admissible in general relativity but inconsistent with Einstein’s original conceptions. Taub’s work drew on Luigi Bianchi’s earlier classification of 3-manifolds that admit various types of actions under local Lie groups. After sketching this general background, I will turn to the pioneering work of Engelbert Schücking, whose 1957 seminar lectures in Hamburg outlined a general approach to studies of Bianchi spacetimes. Schücking’s contributions to relativistic cosmology and other topics in general relativity were alluded to in the Festschrift volume edited by Alex Harvey and published in 1999.
David E. Rowe (University of Mainz)
Title: Rotating Models in Relativistic Cosmology, 1950 to 1970
Abstract: This talk will survey work on early models in relativistic cosmology leading to various rotating models from the period 1950 to 1970. Much of this work had direct roots in Mach’s principle, which Einstein first formulated in 1918. These issues were discussed from the perspective of the mid-1990s in the book by Ciufolini and Wheeler, Gravitation and Inertia. Their account takes up some of the cosmological models with rotation that began with the work of Kurt Gödel. Both Gödel and Abraham Taub saw their global solutions of Einstein’s equations as anti-Machian, in the sense that these rotating models were theoretically admissible in general relativity but inconsistent with Einstein’s original conceptions. Taub’s work drew on Luigi Bianchi’s earlier classification of 3-manifolds that admit various types of actions under local Lie groups. After sketching this general background, I will turn to the pioneering work of Engelbert Schücking, whose 1957 seminar lectures in Hamburg outlined a general approach to studies of Bianchi spacetimes. Schücking’s contributions to relativistic cosmology and other topics in general relativity were alluded to in the Festschrift volume edited by Alex Harvey and published in 1999.
December 3rd, 2024 - Manuel Herrera
hybrid (in-person speaker)
Manuel Herrera (Pontifical Catholic University of Chile)
Title: The implications of general relativity for super-substantivalist metaphysics.
Abstract: In contrast to substantialism, super-substantialism claims that the only substance is space-time and that matter can be "reduced" (through some particular relation) to points/regions of it. In recent years, super-substantivalism has been strongly discussed in the domain of analytical metaphysics, but very little in the domain of physics (some exceptions are Lehmkuhl, 2016; Dürr and Calosi, 2021). In order to contribute to the development of super-substantivalism in the latter domain, I delineate a super-substantivalist interpretation of general relativistic space-time based on the substratum theory of objects and determinable/determined properties. This interpretation has its origins in the different ways in which it is possible to understand a "field" in modern field theories such as general relativity.
Manuel Herrera (Pontifical Catholic University of Chile)
Title: The implications of general relativity for super-substantivalist metaphysics.
Abstract: In contrast to substantialism, super-substantialism claims that the only substance is space-time and that matter can be "reduced" (through some particular relation) to points/regions of it. In recent years, super-substantivalism has been strongly discussed in the domain of analytical metaphysics, but very little in the domain of physics (some exceptions are Lehmkuhl, 2016; Dürr and Calosi, 2021). In order to contribute to the development of super-substantivalism in the latter domain, I delineate a super-substantivalist interpretation of general relativistic space-time based on the substratum theory of objects and determinable/determined properties. This interpretation has its origins in the different ways in which it is possible to understand a "field" in modern field theories such as general relativity.
December 10th, 2024 - Student Presentations
In-person only
Student Presentations.
Student Presentations.
December 17th, 2024 - Dennis Lehmkuhl & Christian Röken
hybrid (in-person speaker)
Dennis Lehmkuhl & Christian Röken (University of Bonn)
Title: Penrose's analogy between gravitational and optical systems
Abstract: We present an analysis of the analogy between the focusing effects of particular families of Ricci- and Weyl-curved spacetime regions on the one hand and anastigmatic and astigmatic optical lenses on the other. This gravito-optical analogy was pioneered by Roger Penrose in the early 1960s. We put the analogy in its historical context, showing among other things how Penrose drew on results of Ray Sachs, and investigate its underlying assumptions, its range of validity, and how it should be interpreted.
Dennis Lehmkuhl & Christian Röken (University of Bonn)
Title: Penrose's analogy between gravitational and optical systems
Abstract: We present an analysis of the analogy between the focusing effects of particular families of Ricci- and Weyl-curved spacetime regions on the one hand and anastigmatic and astigmatic optical lenses on the other. This gravito-optical analogy was pioneered by Roger Penrose in the early 1960s. We put the analogy in its historical context, showing among other things how Penrose drew on results of Ray Sachs, and investigate its underlying assumptions, its range of validity, and how it should be interpreted.
January 7th, 2025 - Oliver Passon
hybrid (in-person speaker)
Oliver Passon (Wuppertal)
Title: Issues with quantum mechanics in the most elementary applications.
Oliver Passon (Wuppertal)
Title: Issues with quantum mechanics in the most elementary applications.
January 14th, 2025 - Pavel Kroupa
hybrid (in-person speaker)
Pavel Kroupa (University of Bonn)
Title: The dark-matter-free universe: the application of Chandrasekhar dynamical friction to test for dark matter particles and the consequences for fundamental physics thereof.
Pavel Kroupa (University of Bonn)
Title: The dark-matter-free universe: the application of Chandrasekhar dynamical friction to test for dark matter particles and the consequences for fundamental physics thereof.
January 21st, 2025 - Carlos Barcelo Seren
hybrid (in-person speaker)
Carlos Barcelo Seren (Instituto de Astrofisica de Andalucía)
Title: Harmonic conditions in general relativity: mathematical simplicity or physical reality?
Carlos Barcelo Seren (Instituto de Astrofisica de Andalucía)
Title: Harmonic conditions in general relativity: mathematical simplicity or physical reality?
January 28th, 2025 - Patrick Dürr
hybrid (in-person speaker)
Patrick Dürr (University of Tübingen)
Title: The change-driver account of scientific discoveries. Philosophical and historical dimensions of the discovery of the expanding universe.
Patrick Dürr (University of Tübingen)
Title: The change-driver account of scientific discoveries. Philosophical and historical dimensions of the discovery of the expanding universe.
Other Events - Talks of Group Members
November 18th - Dennis Lehmkuhl at BHI Foundations Seminar
BHI Foundations Seminar
Monday, November 18th, at 9:30 AM (ET).
Dennis Lehmkuhl (University of Bonn) will present:
"What does it mean to be a realist about dark matter and black holes?"
Abstract: Martens (2022) argues that the concept of dark matter as it appears in and is constrained by the standard model of cosmology is too thin a concept to justify being a realist about dark matter. Simply put, he argues that we don’t yet know enough about dark matter for us to be justified in believing in its existence. In this talk, I will compare the case for and against being a realist about dark matter to the case for and against being a realist about black holes. In the course of the comparison, I will investigate the very concept of matter as it features in General Relativity and Cosmology, and argue that one needs to know less than expected about something (and dark matter and black holes in particular) to know that it is there.
This is the first talk in our three-part series on dark matter.
Location:
In-person: BHI Seminar Room (2nd floor)
Online: Join via Zoom
(Meeting ID: 941 9420 3010, Password: HarvardBHI)
The talk will also be recorded and shared on the BHI YouTube channel.
Monday, November 18th, at 9:30 AM (ET).
Dennis Lehmkuhl (University of Bonn) will present:
"What does it mean to be a realist about dark matter and black holes?"
Abstract: Martens (2022) argues that the concept of dark matter as it appears in and is constrained by the standard model of cosmology is too thin a concept to justify being a realist about dark matter. Simply put, he argues that we don’t yet know enough about dark matter for us to be justified in believing in its existence. In this talk, I will compare the case for and against being a realist about dark matter to the case for and against being a realist about black holes. In the course of the comparison, I will investigate the very concept of matter as it features in General Relativity and Cosmology, and argue that one needs to know less than expected about something (and dark matter and black holes in particular) to know that it is there.
This is the first talk in our three-part series on dark matter.
Location:
In-person: BHI Seminar Room (2nd floor)
Online: Join via Zoom
(Meeting ID: 941 9420 3010, Password: HarvardBHI)
The talk will also be recorded and shared on the BHI YouTube channel.
|
2023/2024
|
Bonn History and Philosophy of Physics Research Seminar (Summer)
Time & Place:
Tuesdays from 14:15 to 15:45 CEST.
Almost all sessions can be attended via Zoom; the sessions that are indicated as 'hybrid' below may also be attended in person, in the main building (Am Hof 1, 53113 Bonn) in seminar room 1.070. Zoom-links and weekly reminders are announced via [email protected]. Subscribing to this list is possible
a) here,
b) by sending an empty email to [email protected],
or c) by contacting [email protected]
Conveners:
Dr. Juliusz Doboszewski, Prof. Dr. Dennis Lehmkuhl, Nurida Boddenberg
9 April 2024
hybrid (in-person speaker)
Karim Thébault (University of Bristol)
Decoherence and Probability
Abstract
In what follows, we start by introducing two important types of probability structures: quasi-probability structures and classical probability structures. The first is a generalisation of the second. Each will be understood as uninterpreted formal structures. We will then show how the two structures can be augmented and partially interpreted to provide representations of possibility space models that implement quasi-probabilistic and classical probabilistic structure respectively. These representations correspond to classical statistical mechanics and quantum mechanics. Finally, we consider a model for the emergence of a classical possibility space from a quantum possibly space model based upon the combination of decoherence and the ℏ → 0 limit. We will conclude by considering implications for debates regarding the emergence of probability in the many worlds interpretation as discussed in recent work by Saunders (2021) and Franklin (2023).
Saunders, S. W. (2021). The Everett interpretation: Probability 1. In The Routledge companion to philosophy of physics, pp. 230–246. Routledge. arXiv:2103.03966
Franklin, A. (2023). Incoherent? No, just Decoherent: How quantum many worlds emerge. Philosophy of Science DOI: 10.1017/psa.2023.155. https://philsci-archive.pitt.edu/22713/
30 April 2024
hybrid (in-person speaker)
Jürgen Renn (Max Planck Institute of Geoanthropology)
David Bohm‘s lectures on quantum theory and dialectical materialism
Abstract
The talk presents recently discovered notes by David Bohm, related to lectures he delivered in 1957 to a group of Marxist physicists at meetings organized by the Hashomer Hatsair (Young Guard) movement at their headquarters in Tel-Aviv. They are entitled “Philosophical Problems of Quantum Mechanics in the Light of Dialectic Materialism.” The notes comprise 114 pages printed with a manual duplicating machine. Comparing these lectures to Bohm’s book published in the same year, Causality and Chance in Modern Physics, the most striking difference is that Bohm’s worldview is here presented within an explicit philosophical framework, specifically, in the context of Hegel’s dialectics, transformed by Marx and Engels into dialectical materialism. The talk argues that the inspiration Bohm took from Hegel’s Logic helped him to highlight hitherto neglected aspects of quantum theory such as its non-locality, to challenge the dominance of the Copenhagen interpretation, and to reopen a discussion on the foundations of quantum theory that eventually paved the way for the Second Quantum Revolution.
7 May 2024
In-person only
Frauke Stoll
Understanding Particle Physics with Deep Neural Networks and Explainable Artifical Intelligence
Kartik Tiwari
Painting the Heavens - Supercluster Simulations and Suspicions
Abstract
Even those who adore computer simulations in their astrophysics lectures, may fear them through their philosophy education. Our computers cannot simulate the largest structures of our universe while resolving their (cosmological) smallest blocks. We can, however, approximately ‘infer’ the effects of one on the other. But, how well do these approximations align with the (so-called) spirit of science? I probe this question by dissecting the theoretical, experimental, and epistemic status of 'painting'-styled approximations in cosmology. By comparing painting to other classes of scientific approximations, we identify its short-comings on some reasonable constraints on ‘good’ approximations. Towards the end, I try to hint at the structure of possible resolutions for the issues raised through my talk.
14 May 2024
hybrid (in person speaker), all day long
Workshop Foundational Challenges in Cosmological Studies of Black Holes
28 May 2024
hybrid (in person speaker)
Jonathan Fay (Hertz fellow; University of Bristol)
On the Reissner-Sciama hypothesis: Relative motion and the necessary existence of gravitation
Abstract
Shortly after the development of general relativity, it would become clear that Einstein’s general covariance based approach does not reduce inertia to mass interactions. While Einstein subsequently treated “Mach’s principle” as a selection criterion for models of his theory, there is an alternative research program that implements this idea explicitly in its foundation. What I have called the Reissner-Sciama hypothesis combines Mach’s hypothesis concerning the material origin of inertia with Einstein’s equivalence hypothesis (which suggests the unity of gravity and inertia), in such a way that gravity is identified as a necessary side-effect of the relativity of inertia; thus hypothetically explaining the reason for the existence of the gravitational force. A corollary of this hypothesis is that the gravitational “constant” becomes a dynamical variable determined by the cosmic structure.
The key papers I will draw from are Reissner (1915) and Sciama (1953). The first of these provides the best historical articulation of the hypothesis, whereas the second best illustrates the idea mathematically. In the last part of my talk, I will analyse these ideas from the philosophical perspective, discuss what it means for gravity to arise necessarily, and explore the broader implications that this sort of reasoning has for cosmology.
4 June 2024
hybrid (in-person speaker)
Jan Michel (University of Düsseldorf)
Can machines make scientific discoveries?
Abstract
To answer the question of whether machines can make scientific discoveries, two sub-questions need to be answered: (1) What is required to make a scientific discovery? (2) Are machines capable of meeting these requirements? After some remarks on the role of scientific progress and the significance of machines in science, I show how to conceive of scientific discoveries as structured processes with the three indispensable structural features of finding, acceptance, and knowledge (cf. Michel 2022). By elaborating on each of these features, I identify several requirements for artificial discoverers. Turning then to an objection raised by Green (2022), I address two crucial issues: First, the question of whether machines can perform speech acts (cf. Green & Michel 2022), and in particular declarative speech acts. Second, the question of how different institutionalized publication cultures realize what I call acceptance mechanisms. With this in mind, I show how Green’s objection can be met once we distinguish between degrees of acceptance in certain ways. I close with a diagnosis of what to make of the idea of artificial discoverers in science.
11 June 2024
hybrid (in-person speaker)
Tushar Menon (Australian Catholic University)
The inferentialist guide to quantum mechanics
Abstract
This talk introduces a new approach to understanding quantum mechanics (QM) called ‘pure-inferential quantum mechanics.’ The animating thought behind this approach is that, while theories can be about the world without describing it, we would be just as wrong to assume, as anti-realists such as QBists do, that quantum states never describe the world, as we would be to assume, as realists such as Everettians do, that they always do. I marshal some resources from pragmatist philosophy of language to delineate the circumstances under which QM should be understood as descriptive from those under which it should not be. By constructing a novel inferentialist-pragmatist interpretation of QM, I demonstrate, pace Healey, that the inferentialist about QM has the resources to ground an autonomous, descriptive interpretation of QM in its inferential profile, under the appropriate circumstances. I argue that, if we should be inferentialists about QM (and there are good reasons why we should be), then we should be pure-inferentialists.
18 June 2024
In-person only
Alexander Reutlinger (Munich Center for Mathematical Philosophy, LMU Munich)
Articulating Invariantism. Revisiting the Counterfactual Independence Account of Scientific Objectivity
Abstract
Invariantism defines scientific objectivity via the notion of invariance. I will present a version of invariantism, according to which the key notion of invariance is spelled out more precisely as a specific sort of counterfactual independence. This invariantist view – the counterfactual independence account of objectivity – needs to be articulated in a more nuanced manner. To do so, I will first explore under which conditions this version of invariantism is applicable to two different concepts of objectivity: epistemic and structural objectivity. In a second step, I will analyze what the epistemic import of (different concepts of) objectivity is, what objectivity contributes to generating scientific knowledge, if one adopts the sort of invariantism I propose.
25 June 2024
In-person only
Nurida Boddenberg
Overview on Current Topics in the Philosophy of Physics
(no research talsk; presentation for local students)
Abstract
/
2 July 2024
hybrid (in-person speaker)
Alex Mathie (Hertz fellow; MCMP LMU Munich)
Black Holes & Analogy
Abstract
Reasoning using analogies is ubiquitous in science, where observed similarities between different domains might act as heuristics for theory development. In this talk, I explore two instances of analogical reasoning in black hole physics that seem to overreach this traditional heuristic role (analogue gravity, and the formal analogy between the laws of thermodynamics and the laws of black hole mechanics). Furthermore, I argue that not only are these two instances of analogical reasoning connected in an important way, but that the relationship between them induces a tension for those who wish to take black hole thermodynamics seriously, but who are sceptical of the epistemic legitimacy of analogue gravity.
9 July 2024
hybrid (in-person speaker)
Abhay Ashtekar (Physics Department, Penn State, US and Perimeter Institute, Canada)
Einstein’s Universe and the Quantum
Abstract
Our notions of space and time underwent a radical change just over a 100 years ago. Through general relativity, gravity ceased to be a force and became a manifestation of space-time geometry. This paradigm shift opened unforeseen perspectives in our understanding of the physical universe: possibility of ripples in space-time geometries that manifest themselves as gravitational waves; of black holes, representing geometries that trap not only matter but also light; and of the Big Bang, the primordial explosion marking the birth of the space-time continuum itself. However, through black holes and the big bang we also learnt that Einstein’s equations predict the presence of space-time singularities: rugged edges where the space-time continuum tears and all of classical physics comes to an abrupt halt. These singularities are the gates to physics beyond Einstein –i.e., to unification of general relativity with quantum physics. Construction of this desired theory of quantum gravity is a truly challenging task because it requires an entirely new syntax to formulate concepts that are sufficiently adequate to describe the extreme universe. We now need the quantum analog of Riemannian geometry that serves as the syntax for general relativity. After a brief discussion of why several distinct approaches are being pursued, I will focus on loop quantum gravity, based on a specific theory of Riemannian quantum geometry. I will explain how it leads to quantum space-times that extend Einstein’s classical continuum beyond its singularities. While this conceptual framework is rather abstract and involves novel mathematics, it also leads to predictions that can be tested observationally.
Tuesdays from 14:15 to 15:45 CEST.
Almost all sessions can be attended via Zoom; the sessions that are indicated as 'hybrid' below may also be attended in person, in the main building (Am Hof 1, 53113 Bonn) in seminar room 1.070. Zoom-links and weekly reminders are announced via [email protected]. Subscribing to this list is possible
a) here,
b) by sending an empty email to [email protected],
or c) by contacting [email protected]
Conveners:
Dr. Juliusz Doboszewski, Prof. Dr. Dennis Lehmkuhl, Nurida Boddenberg
9 April 2024
hybrid (in-person speaker)
Karim Thébault (University of Bristol)
Decoherence and Probability
Abstract
In what follows, we start by introducing two important types of probability structures: quasi-probability structures and classical probability structures. The first is a generalisation of the second. Each will be understood as uninterpreted formal structures. We will then show how the two structures can be augmented and partially interpreted to provide representations of possibility space models that implement quasi-probabilistic and classical probabilistic structure respectively. These representations correspond to classical statistical mechanics and quantum mechanics. Finally, we consider a model for the emergence of a classical possibility space from a quantum possibly space model based upon the combination of decoherence and the ℏ → 0 limit. We will conclude by considering implications for debates regarding the emergence of probability in the many worlds interpretation as discussed in recent work by Saunders (2021) and Franklin (2023).
Saunders, S. W. (2021). The Everett interpretation: Probability 1. In The Routledge companion to philosophy of physics, pp. 230–246. Routledge. arXiv:2103.03966
Franklin, A. (2023). Incoherent? No, just Decoherent: How quantum many worlds emerge. Philosophy of Science DOI: 10.1017/psa.2023.155. https://philsci-archive.pitt.edu/22713/
30 April 2024
hybrid (in-person speaker)
Jürgen Renn (Max Planck Institute of Geoanthropology)
David Bohm‘s lectures on quantum theory and dialectical materialism
Abstract
The talk presents recently discovered notes by David Bohm, related to lectures he delivered in 1957 to a group of Marxist physicists at meetings organized by the Hashomer Hatsair (Young Guard) movement at their headquarters in Tel-Aviv. They are entitled “Philosophical Problems of Quantum Mechanics in the Light of Dialectic Materialism.” The notes comprise 114 pages printed with a manual duplicating machine. Comparing these lectures to Bohm’s book published in the same year, Causality and Chance in Modern Physics, the most striking difference is that Bohm’s worldview is here presented within an explicit philosophical framework, specifically, in the context of Hegel’s dialectics, transformed by Marx and Engels into dialectical materialism. The talk argues that the inspiration Bohm took from Hegel’s Logic helped him to highlight hitherto neglected aspects of quantum theory such as its non-locality, to challenge the dominance of the Copenhagen interpretation, and to reopen a discussion on the foundations of quantum theory that eventually paved the way for the Second Quantum Revolution.
7 May 2024
In-person only
Frauke Stoll
Understanding Particle Physics with Deep Neural Networks and Explainable Artifical Intelligence
Kartik Tiwari
Painting the Heavens - Supercluster Simulations and Suspicions
Abstract
Even those who adore computer simulations in their astrophysics lectures, may fear them through their philosophy education. Our computers cannot simulate the largest structures of our universe while resolving their (cosmological) smallest blocks. We can, however, approximately ‘infer’ the effects of one on the other. But, how well do these approximations align with the (so-called) spirit of science? I probe this question by dissecting the theoretical, experimental, and epistemic status of 'painting'-styled approximations in cosmology. By comparing painting to other classes of scientific approximations, we identify its short-comings on some reasonable constraints on ‘good’ approximations. Towards the end, I try to hint at the structure of possible resolutions for the issues raised through my talk.
14 May 2024
hybrid (in person speaker), all day long
Workshop Foundational Challenges in Cosmological Studies of Black Holes
28 May 2024
hybrid (in person speaker)
Jonathan Fay (Hertz fellow; University of Bristol)
On the Reissner-Sciama hypothesis: Relative motion and the necessary existence of gravitation
Abstract
Shortly after the development of general relativity, it would become clear that Einstein’s general covariance based approach does not reduce inertia to mass interactions. While Einstein subsequently treated “Mach’s principle” as a selection criterion for models of his theory, there is an alternative research program that implements this idea explicitly in its foundation. What I have called the Reissner-Sciama hypothesis combines Mach’s hypothesis concerning the material origin of inertia with Einstein’s equivalence hypothesis (which suggests the unity of gravity and inertia), in such a way that gravity is identified as a necessary side-effect of the relativity of inertia; thus hypothetically explaining the reason for the existence of the gravitational force. A corollary of this hypothesis is that the gravitational “constant” becomes a dynamical variable determined by the cosmic structure.
The key papers I will draw from are Reissner (1915) and Sciama (1953). The first of these provides the best historical articulation of the hypothesis, whereas the second best illustrates the idea mathematically. In the last part of my talk, I will analyse these ideas from the philosophical perspective, discuss what it means for gravity to arise necessarily, and explore the broader implications that this sort of reasoning has for cosmology.
4 June 2024
hybrid (in-person speaker)
Jan Michel (University of Düsseldorf)
Can machines make scientific discoveries?
Abstract
To answer the question of whether machines can make scientific discoveries, two sub-questions need to be answered: (1) What is required to make a scientific discovery? (2) Are machines capable of meeting these requirements? After some remarks on the role of scientific progress and the significance of machines in science, I show how to conceive of scientific discoveries as structured processes with the three indispensable structural features of finding, acceptance, and knowledge (cf. Michel 2022). By elaborating on each of these features, I identify several requirements for artificial discoverers. Turning then to an objection raised by Green (2022), I address two crucial issues: First, the question of whether machines can perform speech acts (cf. Green & Michel 2022), and in particular declarative speech acts. Second, the question of how different institutionalized publication cultures realize what I call acceptance mechanisms. With this in mind, I show how Green’s objection can be met once we distinguish between degrees of acceptance in certain ways. I close with a diagnosis of what to make of the idea of artificial discoverers in science.
11 June 2024
hybrid (in-person speaker)
Tushar Menon (Australian Catholic University)
The inferentialist guide to quantum mechanics
Abstract
This talk introduces a new approach to understanding quantum mechanics (QM) called ‘pure-inferential quantum mechanics.’ The animating thought behind this approach is that, while theories can be about the world without describing it, we would be just as wrong to assume, as anti-realists such as QBists do, that quantum states never describe the world, as we would be to assume, as realists such as Everettians do, that they always do. I marshal some resources from pragmatist philosophy of language to delineate the circumstances under which QM should be understood as descriptive from those under which it should not be. By constructing a novel inferentialist-pragmatist interpretation of QM, I demonstrate, pace Healey, that the inferentialist about QM has the resources to ground an autonomous, descriptive interpretation of QM in its inferential profile, under the appropriate circumstances. I argue that, if we should be inferentialists about QM (and there are good reasons why we should be), then we should be pure-inferentialists.
18 June 2024
In-person only
Alexander Reutlinger (Munich Center for Mathematical Philosophy, LMU Munich)
Articulating Invariantism. Revisiting the Counterfactual Independence Account of Scientific Objectivity
Abstract
Invariantism defines scientific objectivity via the notion of invariance. I will present a version of invariantism, according to which the key notion of invariance is spelled out more precisely as a specific sort of counterfactual independence. This invariantist view – the counterfactual independence account of objectivity – needs to be articulated in a more nuanced manner. To do so, I will first explore under which conditions this version of invariantism is applicable to two different concepts of objectivity: epistemic and structural objectivity. In a second step, I will analyze what the epistemic import of (different concepts of) objectivity is, what objectivity contributes to generating scientific knowledge, if one adopts the sort of invariantism I propose.
25 June 2024
In-person only
Nurida Boddenberg
Overview on Current Topics in the Philosophy of Physics
(no research talsk; presentation for local students)
Abstract
/
2 July 2024
hybrid (in-person speaker)
Alex Mathie (Hertz fellow; MCMP LMU Munich)
Black Holes & Analogy
Abstract
Reasoning using analogies is ubiquitous in science, where observed similarities between different domains might act as heuristics for theory development. In this talk, I explore two instances of analogical reasoning in black hole physics that seem to overreach this traditional heuristic role (analogue gravity, and the formal analogy between the laws of thermodynamics and the laws of black hole mechanics). Furthermore, I argue that not only are these two instances of analogical reasoning connected in an important way, but that the relationship between them induces a tension for those who wish to take black hole thermodynamics seriously, but who are sceptical of the epistemic legitimacy of analogue gravity.
9 July 2024
hybrid (in-person speaker)
Abhay Ashtekar (Physics Department, Penn State, US and Perimeter Institute, Canada)
Einstein’s Universe and the Quantum
Abstract
Our notions of space and time underwent a radical change just over a 100 years ago. Through general relativity, gravity ceased to be a force and became a manifestation of space-time geometry. This paradigm shift opened unforeseen perspectives in our understanding of the physical universe: possibility of ripples in space-time geometries that manifest themselves as gravitational waves; of black holes, representing geometries that trap not only matter but also light; and of the Big Bang, the primordial explosion marking the birth of the space-time continuum itself. However, through black holes and the big bang we also learnt that Einstein’s equations predict the presence of space-time singularities: rugged edges where the space-time continuum tears and all of classical physics comes to an abrupt halt. These singularities are the gates to physics beyond Einstein –i.e., to unification of general relativity with quantum physics. Construction of this desired theory of quantum gravity is a truly challenging task because it requires an entirely new syntax to formulate concepts that are sufficiently adequate to describe the extreme universe. We now need the quantum analog of Riemannian geometry that serves as the syntax for general relativity. After a brief discussion of why several distinct approaches are being pursued, I will focus on loop quantum gravity, based on a specific theory of Riemannian quantum geometry. I will explain how it leads to quantum space-times that extend Einstein’s classical continuum beyond its singularities. While this conceptual framework is rather abstract and involves novel mathematics, it also leads to predictions that can be tested observationally.
Foundational Challenges in Cosmological Studies of Black Holes - Workshop (14 May 2024)
Date: 14th May 2024
Location: Seminar Room, Center for Science and Thought, University of Bonn
Address: Konrad-Zuse-Platz 1-3, 53227 Bonn (Directions)
With the emergence of new observational windows, black holes are increasingly used in constraining cosmological theories. This workshop aims to address the major foundational and methodological challenges in cosmological studies of black holes: What are the methodological principles of these searches? What should we expect from future observations? How do long-standing research programs look from the new vantage points? What foundational lessons can be drawn from cosmological studies of new physics? The workshop will facilitate a multi-disciplinary perspective on the cosmological implications of black holes, by bringing together contributions from theoretical physics, astronomy, and the philosophy of physics.
List of speakers:
Kristen Lackeos (Max-Planck-Institut für Radioastronomie, Bonn)
Antonia Frassino (University of Barcelona)
Jamee Elder (Tufts University)
Erik Curiel (University of Bonn, Harvard University’s Black Hole Initiative)
Juliusz Doboszewski (University of Bonn, Harvard University’s Black Hole Initiative)
Main topics of the workshop include, but are not limited to:
- primordial black holes as dark matter candidates
- epistemology of gravitational wave astrophysics
- model agnostic searches and notions of model independence
- philosophical issues in multi-messenger astronomy
- alternatives to black holes
- statistical wars in astrophysics and cosmology
- foundational issues in black hole physics
Attendance to the workshop is free and open to everyone, however, all participants are required to register by 30th April by sending an email to: [email protected] Attendance via zoom is also possible, the link will be shared with all registered participants in due time. When registering please indicate whether you are planning to participate in-person or online.
Organizers:
- Antonis Antoniou ([email protected])
- Juliusz Doboszewski ([email protected])
This workshop is funded by the Deutsche Forschungsgemeinschaft DFG Project "Inductive Metaphysics".
Schedule:
09:00 – 10:00Antonia Frassino (Universitat de Barcelona)
Multimessenger physics, gravitational waves and black holes.
Abstract:
Potential experimental signatures of the quantum nature of gravity are becoming a thriving field with a multitude of approaches in different directions. In this talk I will first overview the contribution of gravitational waves to multimessenger physics, their connection to black holes, and then focus on quantum signatures at gravitational wave detectors.
10:00 – 11:00 Erik Curiel (University of Bonn & Black Hole Initiative Harvard)
Black Holes, Compact Horizonless Objects or Naked Singularities?
Abstract:
Thanks to the studies of the motion of stars by Ghenzel and Ghez near Sagittarius A-Star at the center of the Milky Way, for which they were awarded the 2020 Nobel Prize (shared with Penrose for theoretical work), the more recent observations of gravitational waves by the LIGO Scientific Collaboration, and the images produced even more recently by the Event Horizon Telescope, we have strong evidence for the existence of black holes. The purportedly parlous epistemic character of arguments and conclusions in astrophysics, however, especially with regard to the interpretation of observations, seemingly leaves us with much more uncertainty about such claims than is usual for comparable claims that accrue such widespread acclaim in most other fields of physics. Indeed, the announcement of Ghenzel's and Ghez's portion of the award by the Nobel Committee commended them for "the discovery of a supermassive compact object at the centre of our galaxy", not even using the term 'black hole'. Although most serious physicists believe that those physical systems we have observed are indeed black holes, there is enough uncertainty that the mettle of science demands we explore possible alternatives. In this talk, I examine some of the menagerie of theoretically characterized systems proposed as possible alternatives---primarily compact horizonless objects and naked singularities---and discuss their epistemic status, including how well they fit the observations. Along the way, I critically examine the commonly held idea that such existence assertions in astrophysics are significantly more uncertain than in most other fields of physicsAbstract: Thanks to the studies of the motion of stars by Ghenzel and Ghez near Sagittarius A-Star at the center of the Milky Way, for which they were awarded the 2020 Nobel Prize (shared with Penrose for theoretical work), the more recent observations of gravitational waves by the LIGO Scientific Collaboration, and the images produced even more recently by the Event Horizon Telescope, we have strong evidence for the existence of black holes. The purportedly parlous epistemic character of arguments and conclusions in astrophysics, however, especially with regard to the interpretation of observations, seemingly leaves us with much more uncertainty about such claims than is usual for comparable claims that accrue such widespread acclaim in most other fields of physics. Indeed, the announcement of Ghenzel's and Ghez's portion of the award by the Nobel Committee commended them for "the discovery of a supermassive compact object at the centre of our galaxy", not even using the term 'black hole'. Although most serious physicists believe that those physical systems we have observed are indeed black holes, there is enough uncertainty that the mettle of science demands we explore possible alternatives. In this talk, I examine some of the menagerie of theoretically characterized systems proposed as possible alternatives---primarily compact horizonless objects and naked singularities---and discuss their epistemic status, including how well they fit the observations. Along the way, I critically examine the commonly held idea that such existence assertions in astrophysics are significantly more uncertain than in most other fields of physics.
11:00 – 11:30 Coffee break
11:30 – 12:00 Manus Visser (University of Cambridge)
The Holographic Dual of Black Hole Thermodynamics
Abstract:
Black hole thermodynamics contains important clues for quantum gravity. Often black hole entropy is viewed as a low-energy constraint that every quantum theory of gravity has to satisfy. However, black hole thermodynamics itself poses conceptual puzzles, since it contains certain features that are seemingly different from those in standard textbook thermodynamics. For instance, black hole entropy scales with the horizon area, unlike the entropy of standard thermal systems that is proportional to the volume. Another puzzle is that the first law of black hole mechanics does not seem to contain a pressure-volume work term. These and other disanalogies between black hole thermodynamics and standard thermodynamics have led philosophers to argue that black holes are not really thermodynamic. In this talk I will explain how holography or gauge/gravity duality resolves these puzzles in an interesting way. In such a framework black holes in the ‘bulk’ geometry are dual to thermal states in the ‘boundary’ field theory. Crucially, these thermal states satisfy the usual laws of thermodynamics. I will develop a novel holographic ‘dictionary’ that relates the nonstandard laws of black hole thermodynamics to the standard laws of the dual field theory thermodynamics.
12:00 – 12:30 Juliusz Doboszewski (University of Bonn & Black Hole Initiative, Harvard)
Speculative eliminative reasoning: on primordial black holes and their remnants (joint work with Mike Schneider)
Abstract:
Primordial black holes and their remnants can be used to construct various cold dark matter models. But PBHs remain unconfirmed, in that the outcomes of current observations are negative and continue the trend of successively ruling regions of viable parameters; and their remnants have highly speculative character. How to, then, assess their relevance to the ongoing cosmological research? We argue that despite these difficulties, the dark matter problem in late-stage cosmology can be seen as providing a rich empirical access point for investigations within early universe quantum gravity phenomenology. It is also an access point ready for philosophical investigations, including explicating notions of stability used in the context of remnant solutions; the extent to which the search for quantum gravity indeed lacks empirical input; the kind of eliminative reasoning used in searches for PHBs; and the issue of epistemic value of negative empirical results.
12:30 – 13:00 Kiril Maltsev (Heidelberg Institute for Theoretical Studies)
What is the ultimate fate of matter in stellar gravitational collapse?
Abstract:
Stellar gravitational collapse provides a generic mechanism for the possible formation of gravitational singularities. Depending on the adopted physics, the collapse results in formation of a geodesically incomplete spacetime, of infinite curvature, of both pathology types, or none. This generic mechanism is not based only upon purely theoretical, conditions permitted to occur by General Relativity, but connects to well established astrophysical theory. In the fluid dynamical modelling of matter, it is the Equation of State (EoS) that bridges the macroscopic properties of the fluid to the microphysics.However, already at densities beyond nuclear saturation–conditions governing the inner cores of Neutron Stars-the EoS is not tightly constrained, because theory of matter is not well established at these extreme conditions. Therefore, the final stages and ultimate outcome of matter collapse cannot be predicted without adopting heuristic physics assumptions. In this work, we review some of the most prominent assumptions about the ultimate stages of collapse dynamics which have been formulated within the decades spanning in between 1916 and 1965. We investigate (i.) what kind of remnant, and (ii.) which (if any) kind of gravitational singularity is left behind stellar gravitational collapse, depending on the adopted collapse dynamics.
13:00 – 14:30 Lunch break
14:30 – 15:00
Pavel Kroupa (University of Bonn)
The rapid formation of supermassive black holes
Abstract:
From the study of their stellar populations it is well known that elliptical galaxies and bulges formed with star formation rates (SFR) up to 10^4Msun/yr within a Gyr of the Big Bang. Extragalactic observations also inform us that the mass of the most massive forming star cluster in a star-forming galaxy increases with the SFR of the galaxy. We also have a good knowledge of the stellar population in such star-burst clusters. This knowledge, as described by the "IGIMF Theory", is combined with the large SFRs of the forming elliptical galaxies and bulges finding that the centre-most most-massive cluster develops quasar-like luminosities within the first few Myr. Once the population of massive stars has evolved to black holes and neutron stars, gas from the still-forming elliptical galaxy falls into it. As a consequence, the cluster of remnants contracts until it becomes relativistic, at which point is collapses rapidly to a supermassive black hole (SMBH) through emission of gravitational waves. The time from the start of the formation of the elliptical galaxy to the formation of the SMBH is shorter than 200-300 Myr. The calculations automatically produce the observed correlation between the host-galaxy properties and the mass of the SMBH and show that ellipticals and bulges less massive than a few 10^9Msun retain a central nuclear star cluster rather than an SMBH, as is observed.
15:00 –15:30 Paula Muhr (University of Zurich, TU Berlin)
Epistemic Critique Performed by Recent Reanalyses of the EHT Images of theM87* Black Hole
Abstract:
April 2019, the Event Horizon Telescope (EHT) Collaboration famously revealed the first empirical images of a black hole, a cosmic object thus far regarded ‘unseeable’. These revolutionary images that visualise the immediate surrounding of the black hole at the centre of the galaxy Messier 87 were algorithmically reconstructed from non-visual data obtained by an array of radio telescopes. To obtain valid imaging results, the EHT team deployed multiple methodologies during the image reconstruction process, which all delivered sufficiently consistent results. Besides revealing their final images, the team also made their processed data and algorithms accessible to the public. In 2022, five studies authored by scientists who were not members of the EHT team were published. Each study focused on reanalysing the publicly available EHT data, testing if they would obtain sufficiently similar images of the black hole. The purpose was to verify the epistemic truth claims of the EHT’s final images of the black hole. The authors of each study thereby deployed different approaches. Some replicated the procedure developed by the EHT team; others developed alternative algorithmic techniques for reconstructing images from the EHT non-visual data. Four of the five critical reanalyses converged on their findings by obtaining images that were sufficiently similar to the initial EHT images published in 2019. One study diverged in their results and was subsequently criticised by the EHT team for its methodology. Yet, I will argue that regardless of whether or not they obtained reconstructed images that were sufficiently similar to the EHT images, each reanalysis performed a significant epistemic critique in its own right. I will further claim that far from challenging the EHT results, such epistemic critiques are of critical importance for the epistemological consolidation of the emerging research field of black hole imaging by generating fine-grained methodological insights that have the potential to inform future black hole imaging.
15:30 – 16:00 Coffee break
16:00 – 17:00
..Kristen Lackeos
Gravitational waves from an inhomogeneous Keplerian accretion disk around a supermassive black hole
Abstract: The possibility of gravitational wave emission from an accretion disk orbiting the supermassive black hole of an AGN is investigated, with emphasis on the role of density perturbations. For a Keplerian disk of small and constant thickness, the total luminosity is proportional to the mass variance across the entire disk (which is observationally determined from AGN variability) with the differential variance per annulus being proportional to the cube of the radius for constant dissipative mass inflow. For a black hole of mass 5×10^8 M⊙, the strain of the gravitational waves at a wavelength of 6×10^16 cm and from a distance of 1 Gpc is comparable to the stochastic background of binaries. The luminosity spectrum is proportional to λ^−5/3, with a total luminosity ∼ 7×10^46 ergs/s, on par with the Eddington luminosity. Thus a large viscosity within the disk is not necessarily the cause of copious loss of energy and angular momentum by the disk.
17:00 – 18:00
Jamee Elder (Tufts University & Black Hole Initiative, Harvard)
Cosmological Inferences from the Black Hole Fossil Record
Abstract:
In recent years, gravitational-wave observations have uncovered a population of binary black hole mergers. Other observations---e.g., by the EHT and JWST---have provided new insights about supermassive black holes in both the early and late universe. However, understanding the formation and evolution of the black holes we observe remains an open problem in astrophysics. In this talk I will discuss recent efforts to understand black hole "seeds", their evolution into observed black hole populations, and the use of these populations in making cosmological inferences. I then discuss some philosophical upshots for understanding the methodology of these investigations, in light of the interdependence of these inferences. First, I demonstrate parallels with the methods of (other) historical sciences (e.g., geology and paleontology), including the challenges of disentangling actual causal histories from "how possibly" explanations; second, I argue that "epistemic iteration" (Chang, 2004) enables an understanding of these methods that casts the inferential circularities and degeneracies as virtuous rather than vicious.
18:30 Dinner at Rohmühle restaurant nearby
Bonn History and Philosophy of Physics Research Seminar (Winter)
Time & Place:
Tuesdays from 14:15 to 15:45 CEST.
Almost all sessions can be attended via Zoom; the sessions that are indicated as 'hybrid' below may also be attended in person, in the main building (Am Hof 1, 53113 Bonn) in seminar room 1.070. Zoom-links and weekly reminders are announced via [email protected]. Subscribing to this list is possible
a) here,
b) by sending an empty email to [email protected],
or c) by contacting [email protected]
Conveners:
Dr. Juliusz Doboszewski & Prof. Dr. Dennis Lehmkuhl
17 Oct 2023
hybrid (in person speaker)
Michel Janssen (University of Minnesota)
Drawing the line between kinematics and dynamics in special relativity and quantum mechanics
Abstract
The mathematical equivalence of matrix and wave mechanics papers over an important difference in what Heisenberg and Schrödinger took to be their key insights. For Schrödinger it was that atomic physics calls for an underlying wave theory just as geometric optics had in the 19th century. For Heisenberg it was that atomic physics calls for a new general framework for doing physics just as electrodynamics had in the early-20th century. Following Heisenberg rather than Schrödinger, I present a few case studies in special relativity and quantum mechanics in which problems that seem to call for dynamical solutions were solved instead by an appeal to the new kinematical frameworks introduced by these new theories. I use these case studies to bring out some parallels between the standard take on special relativity and a more controversial information-theoretic take on quantum mechanics and use the former to argue for the latter. Based on joint work with Michael Janas and Mike Cuffaro.
24 Oct 2023
Cancelled
31 Oct 2023
hybrid (in person speaker)
Jose Senovilla (University of the Basque Country)
Singularity Theorems: a critical evaluation
Abstract
After describing the historical context before the publication of Penrose’s singularity theorem, I will briefly discuss the key novel assumptions in the theorem and its immediate impact. A more general discussion of singularity theorems will follow, emphasizing their relevance in Cosmology and for gravitational collapse. A critical appraisal of the theorems and their consequences will then be presented, specifically trying to rebut many inaccurate “folklore” knowledge around the subject. Illustrative examples will be shown throughout.
14 Nov 2023
Workshop on Oppenheimer, Heisenberg, and the birth of nuclear weapons. For further information see here: oppenheimer_event.pdf.
21 Nov 2023
hybrid (in person speaker)
Michael te Vrugt (DAMTP, Centre for Mathematical Sciences, University of Cambridge)
Coarse-graining in cosmology
Abstract
Cosmological models assume the universe to be homogenous on large scales, which corresponds to an averaged ("coarse-grained") description. Coarse-graininig, however, is both mathematically and philosophically quite challenging. For example, the derivation of the Friedmann equations corresponds to a mathematically incorrect coarse-graininig procedure, and it is not clear at present what consequences this has for their accuracy. From the philosophical side, a major question is the justification of coarse-graininig [1]. In this talk, I will first show how the Mori-Zwanzig formalism, a technique from nonequilibrium statistical mechanics, allows to develop improved coarse-grained cosmological models [2]. I will then use this derivation as a case study to argue that, contrary to some claims made in the philosophical literature, justifications of coarse-graininig often involve epistemic and observer-dependent considerations - and that this is not problematic [3].
[1] M. te Vrugt, Studies in History and Philosophy of Science 87, 136-146 (2021)
[2] M. te Vrugt, S. Hossenfelder and R. Wittkowski, Physical Review Letters 127, 231101 (2021)
[3] M. te Vrugt, European Journal for Philosophy of Science 12, 41 (2022)
28 Nov 2023
hybrid (in person speaker)
Antonis Antoniou (University of Bonn)
Laws and Initial Conditions in Cosmology.
Abstract
Two notable characteristics that set cosmology apart from other fields of physics are the uniqueness of its main object of study -- the universe -- and the fact that the initial conditions of the cosmos appear to be necessary rather than contingent. These two characteristics are in tension with two well-established philosophical views about laws and initial conditions: (a) that laws must apply to multiple instances of a physical phenomenon and (b) that initial conditions are distinguished from laws by virtue of their contingency. The present article provides a framework for the resolution of this tension by defining scientific laws as guiding principles within the models of a theory, and initial conditions as the values of parameters to which such laws remain invariant. This framework facilitates the understanding of scientific laws that apply to only one object, and preserves the distinction between laws and initial conditions despite the fact that the latter may not always be contingent.
5 Dec 2023
hybrid (in person speaker)
Paul Hoyningen-Huene (Leibniz Universität Hannover, Institute of Philosophy, Professor emeritus & Universität Zürich, Department of Economics, Lecturer)
How do robust abstract economic models explain?
Abstract
I shall try to answer the question how robust abstract economic models explain; my main illustrative example is the Schelling (Sakoda) model of (racial) segregation. I shall presuppose that abstract economic models deliver for the real world how-possibly explanations at best. The crucial question is how can model results be transferred to real-world phenomena. I shall propose to reframe this transfer problem in the following way. Robust model results inductively support a conjectured, non-obvious logical truth that can be immediately applied both to the model world and to the real world, thereby delivering how-possibly explanations. I shall develop this thesis in 12 steps gradually dismantling its counter-intuitive character. The result will be that the function of robust abstract models is to tease out non-obvious explanatory consequences of theories (evolutionary theory, e.g.) or mechanisms (Schelling dynamics, e.g.) that cannot be directly inferred from them.
19 Dec 2023
hybrid (in person speaker)
Florian Boge (TU Dortmund)
Deep Learning Robustness for Scientific Discovery: The Case of Anomaly Detection in High Energy Physics [Joint work with Michael Krämer, ThHEP, Aachen, & Christian Zeitnitz, ExpHEP, Wuppertal]
Abstract
Machine Learning (ML) techniques such as Deep Neural Networks (DNNs) are of great promise in science today. In High Energy Physics in particular, they are supposed to foster scientific discovery through the detection of anomalies, without reliance on any specific theory or model. But DNNs also have astonishing shortcomings, as they are vulnerable to ‘adversarial examples’; data instances that are easily classifiable for humans but totally misclassified by DNNs. Adversarial vulnerability is a double-edged sword: On the one hand, it shows that discerning DNNs’ credible outputs from flukes requires some skill. On the other hand, adversarials exhibit DNNs’ sensitivity to subtle, often human-inscrutable features that could also be scientifically productive (Buckner [2020]). Such features are, in fact, being utilised in anomaly detection. Against this backdrop, we offer an analysis of, and a cautionary tale about, DNNs’ present utility for scientific discovery. To do so, we introduce a notion of performance-robustness, which DNNs need to satisfy in order to be able to deliver genuine discoveries. However, as we shall also argue, the achievement of performance-robustness often, if not always, implies limitations to purely ML-driven discovery.
16 Jan 2023
hybrid (in person speaker)
15:15-16:45 (one hour later than usual)
Caspar Jacobs (Leiden University)
A Philosophical Introduction to Hidden Symmetries
Abstract
23 Jan 2023
online
Jamie Shaw
“Fund People, not Projects”: From Narrative CVs to Affirmative Action in Science Funding Policy
Abstract
.30 Jan 2023
hybrid (in person speaker)
Kian Salimkhani (Universität zu Köln)
On progress in metaphysics (joint work w/ Matthias Rolffs)
Tuesdays from 14:15 to 15:45 CEST.
Almost all sessions can be attended via Zoom; the sessions that are indicated as 'hybrid' below may also be attended in person, in the main building (Am Hof 1, 53113 Bonn) in seminar room 1.070. Zoom-links and weekly reminders are announced via [email protected]. Subscribing to this list is possible
a) here,
b) by sending an empty email to [email protected],
or c) by contacting [email protected]
Conveners:
Dr. Juliusz Doboszewski & Prof. Dr. Dennis Lehmkuhl
17 Oct 2023
hybrid (in person speaker)
Michel Janssen (University of Minnesota)
Drawing the line between kinematics and dynamics in special relativity and quantum mechanics
Abstract
The mathematical equivalence of matrix and wave mechanics papers over an important difference in what Heisenberg and Schrödinger took to be their key insights. For Schrödinger it was that atomic physics calls for an underlying wave theory just as geometric optics had in the 19th century. For Heisenberg it was that atomic physics calls for a new general framework for doing physics just as electrodynamics had in the early-20th century. Following Heisenberg rather than Schrödinger, I present a few case studies in special relativity and quantum mechanics in which problems that seem to call for dynamical solutions were solved instead by an appeal to the new kinematical frameworks introduced by these new theories. I use these case studies to bring out some parallels between the standard take on special relativity and a more controversial information-theoretic take on quantum mechanics and use the former to argue for the latter. Based on joint work with Michael Janas and Mike Cuffaro.
24 Oct 2023
Cancelled
31 Oct 2023
hybrid (in person speaker)
Jose Senovilla (University of the Basque Country)
Singularity Theorems: a critical evaluation
Abstract
After describing the historical context before the publication of Penrose’s singularity theorem, I will briefly discuss the key novel assumptions in the theorem and its immediate impact. A more general discussion of singularity theorems will follow, emphasizing their relevance in Cosmology and for gravitational collapse. A critical appraisal of the theorems and their consequences will then be presented, specifically trying to rebut many inaccurate “folklore” knowledge around the subject. Illustrative examples will be shown throughout.
14 Nov 2023
Workshop on Oppenheimer, Heisenberg, and the birth of nuclear weapons. For further information see here: oppenheimer_event.pdf.
21 Nov 2023
hybrid (in person speaker)
Michael te Vrugt (DAMTP, Centre for Mathematical Sciences, University of Cambridge)
Coarse-graining in cosmology
Abstract
Cosmological models assume the universe to be homogenous on large scales, which corresponds to an averaged ("coarse-grained") description. Coarse-graininig, however, is both mathematically and philosophically quite challenging. For example, the derivation of the Friedmann equations corresponds to a mathematically incorrect coarse-graininig procedure, and it is not clear at present what consequences this has for their accuracy. From the philosophical side, a major question is the justification of coarse-graininig [1]. In this talk, I will first show how the Mori-Zwanzig formalism, a technique from nonequilibrium statistical mechanics, allows to develop improved coarse-grained cosmological models [2]. I will then use this derivation as a case study to argue that, contrary to some claims made in the philosophical literature, justifications of coarse-graininig often involve epistemic and observer-dependent considerations - and that this is not problematic [3].
[1] M. te Vrugt, Studies in History and Philosophy of Science 87, 136-146 (2021)
[2] M. te Vrugt, S. Hossenfelder and R. Wittkowski, Physical Review Letters 127, 231101 (2021)
[3] M. te Vrugt, European Journal for Philosophy of Science 12, 41 (2022)
28 Nov 2023
hybrid (in person speaker)
Antonis Antoniou (University of Bonn)
Laws and Initial Conditions in Cosmology.
Abstract
Two notable characteristics that set cosmology apart from other fields of physics are the uniqueness of its main object of study -- the universe -- and the fact that the initial conditions of the cosmos appear to be necessary rather than contingent. These two characteristics are in tension with two well-established philosophical views about laws and initial conditions: (a) that laws must apply to multiple instances of a physical phenomenon and (b) that initial conditions are distinguished from laws by virtue of their contingency. The present article provides a framework for the resolution of this tension by defining scientific laws as guiding principles within the models of a theory, and initial conditions as the values of parameters to which such laws remain invariant. This framework facilitates the understanding of scientific laws that apply to only one object, and preserves the distinction between laws and initial conditions despite the fact that the latter may not always be contingent.
5 Dec 2023
hybrid (in person speaker)
Paul Hoyningen-Huene (Leibniz Universität Hannover, Institute of Philosophy, Professor emeritus & Universität Zürich, Department of Economics, Lecturer)
How do robust abstract economic models explain?
Abstract
I shall try to answer the question how robust abstract economic models explain; my main illustrative example is the Schelling (Sakoda) model of (racial) segregation. I shall presuppose that abstract economic models deliver for the real world how-possibly explanations at best. The crucial question is how can model results be transferred to real-world phenomena. I shall propose to reframe this transfer problem in the following way. Robust model results inductively support a conjectured, non-obvious logical truth that can be immediately applied both to the model world and to the real world, thereby delivering how-possibly explanations. I shall develop this thesis in 12 steps gradually dismantling its counter-intuitive character. The result will be that the function of robust abstract models is to tease out non-obvious explanatory consequences of theories (evolutionary theory, e.g.) or mechanisms (Schelling dynamics, e.g.) that cannot be directly inferred from them.
19 Dec 2023
hybrid (in person speaker)
Florian Boge (TU Dortmund)
Deep Learning Robustness for Scientific Discovery: The Case of Anomaly Detection in High Energy Physics [Joint work with Michael Krämer, ThHEP, Aachen, & Christian Zeitnitz, ExpHEP, Wuppertal]
Abstract
Machine Learning (ML) techniques such as Deep Neural Networks (DNNs) are of great promise in science today. In High Energy Physics in particular, they are supposed to foster scientific discovery through the detection of anomalies, without reliance on any specific theory or model. But DNNs also have astonishing shortcomings, as they are vulnerable to ‘adversarial examples’; data instances that are easily classifiable for humans but totally misclassified by DNNs. Adversarial vulnerability is a double-edged sword: On the one hand, it shows that discerning DNNs’ credible outputs from flukes requires some skill. On the other hand, adversarials exhibit DNNs’ sensitivity to subtle, often human-inscrutable features that could also be scientifically productive (Buckner [2020]). Such features are, in fact, being utilised in anomaly detection. Against this backdrop, we offer an analysis of, and a cautionary tale about, DNNs’ present utility for scientific discovery. To do so, we introduce a notion of performance-robustness, which DNNs need to satisfy in order to be able to deliver genuine discoveries. However, as we shall also argue, the achievement of performance-robustness often, if not always, implies limitations to purely ML-driven discovery.
16 Jan 2023
hybrid (in person speaker)
15:15-16:45 (one hour later than usual)
Caspar Jacobs (Leiden University)
A Philosophical Introduction to Hidden Symmetries
Abstract
23 Jan 2023
online
Jamie Shaw
“Fund People, not Projects”: From Narrative CVs to Affirmative Action in Science Funding Policy
Abstract
.30 Jan 2023
hybrid (in person speaker)
Kian Salimkhani (Universität zu Köln)
On progress in metaphysics (joint work w/ Matthias Rolffs)
Uncertainty and Insecurity - Oppenheimer vs. Heisenberg?
Two talks by leading historians of science followed by a podium discussion on 14 Nov 2023
The movie "Oppenheimer" by Christopher Nolan portrays of one of the most critical episodes in 20th-century: the birth of nuclear weapons. Join us for a two talks and a podium discussion on November 14th at the Otto-Deiters-Hörsaal at Anatomisches Institut (Nußallee 10, Bonn). Both talks and the podium discussion will be accessible for the general public. Find the poster here: oppenheimer_event.pdf
The movie "Oppenheimer" by Christopher Nolan portrays of one of the most critical episodes in 20th-century: the birth of nuclear weapons. Join us for a two talks and a podium discussion on November 14th at the Otto-Deiters-Hörsaal at Anatomisches Institut (Nußallee 10, Bonn). Both talks and the podium discussion will be accessible for the general public. Find the poster here: oppenheimer_event.pdf
Michel Janssen (University of Minnesota/University of Bonn)
Reflections on Oppenheimer, the man and the movie (in English)
Abstract
Christopher Nolan‘s movie Oppenheimer raises a number of interesting questions about the life and times of its main subject and off ers a range of answers for viewers to choose from. Why was Oppenheimer in favor of dropping atomic bombs on Hiroshima and Nagasaki? Why did he not become a spokesperson for those among his fellow physicists opposed to their military use? And why then was he adamantly opposed a few years later to the development of the hydrogen bomb? What about his communist sympathies? I will deal with these and further questions as they come up as Oppenheimer‘s life and career unfolds, from US ambassador of quantum mechanics in Berkeley to scientific leader of the Manhattan project in Los Alamos to Einstein‘s boss at the Institute of Advanced Studies in Princeton and prominent adviser to the Truman administration on matters concerning nuclear physics and national security to his fall from grace under Eisenhower and his eventual partial rehabilitation by Kennedy and Johnson.
6.15 pm
Dieter Hoffmann (MPI für Wissenschaftsgeschichte Berlin)
Farm Hall und die Furcht der Alliierten vor der deutschen Atombombe (in German)
Abstract
7.30 pm
Refreshments
8 pm
Podium Discussion in German with Prof. Janssen, Prof. Hoffmann, Prof. Dieter Meschede (Institute for Applied Physics, University of Bonn), Prof. Dr. Carl Christian von Weizsäcker (Department of Economics, University of Cologne).
Moderated by Prof. Dennis Lehmkuhl (University of Bonn).