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current / upcoming
History and Philosophy of Physics Research Seminar

Time and Place:
Vertical Divider
Tuesdays from 16:15 to 17:45 CET.
Online via Zoom.
Zoom-links and weekly reminders are announced via hpp@listen.uni-bonn.de; contact nmartens[at]uni-bonn[dot]de to be added to this mailing list.

Conveners:
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Prof. Dr. Dennis Lehmkuhl & Dr. Niels Martens
3 Nov 2020
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Juliusz Doboszewski (University of Bonn)

Kerr black holes as time machines

Spinning black holes are now considered to be a well-established feature of our universe. However, some maximal extensions of certain spinning black hole spacetimes (such as the Kerr spacetime) have chronology violating regions. How likely is it, then, that our universe contains chronology violating regions? In this talk, I will discuss whether and to what extent spinning black hole spacetimes could be seen as a time machine in some precise sense, and critically assess a recent claim that time machines (and other forms of time travel to the past in general relativity) are incompatible with the second law of thermodynamics.
10 Nov 2020
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Richard Dawid (Stockholm University)
Based on joint work with Casey McCoy (Yonsei University)

How postmodern is cosmic inflation?
 
In 2014, Ijjas, Loeb and Steinhardt (ILS) claimed that the paradigm of eternal inflation had left the regime of canonical scientific reasoning (using the pejorative term postmodern inflation). The debate on their paper eventually led to a highly antagonistic and much publicized exchange between ILS and 40 main exponents of inflation in Scientific American. In my talk I will argue that the irreconcilable positions in this debate have genuine philosophical roots. I will sketch a Bayesian analysis of the problem raised by ILS and will argue that acknowledging the role of meta-empirical theory assessment is helpful for identifying the core of the disagreement.
17 Nov 2020
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Romain Ruzziconi (TU Wien)
 
Asymptotic symmetries in gravity and the BMS group in (A)dS           

I will start this talk by reviewing some aspects of asymptotic symmetries in gauge theories with a focus on General Relativity. I will insist on the deep implications of imposing boundary conditions for the general covariance principle. I will then introduce the notion of asymptotically flat spacetime and define the Bondi-van der Burg-Metzner-Sachs (BMS) group and its various extensions. Afterwards, I will propose a new definition of asymptotically (anti-)de Sitter ((A)dS) spacetime and show that the associated asymptotic symmetry group, called the Λ-BMS group, reduces to one of the extensions of the BMS group in the flat limit. Using the holographic renormalization procedure and a diffeomorphism between Bondi and Fefferman-Graham gauges, I will show that the flat limit is also valid at the level of the phase space.           

Based on: 1905.00971, 1910.08367, 2004.10769.
24 Nov 2020
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Joshua Eisenthal (Caltech & University of Bonn)
 
Hertz’s Mechanics and a unitary notion of force

Heinrich Hertz dedicated the last four years of his life to a systematic reformulation of mechanics. One of the main issues that troubled Hertz in the traditional formulation was a ‘logical obscurity’ in the notion of force. However, it is unclear what this logical obscurity was, hence it is unclear how Hertz took himself to have avoided this obscurity in his own formulation of mechanics.         

In this paper I will first identify an issue concerning the Newtonian conception of force that lay in the background of Hertz’s concerns. I will argue that a subtle ambiguity in Newton’s original laws of motion led to the development of two different notions of force: a vectorial notion and a variational notion. I will then explore how Hertz employed the mathematical apparatus of differential geometry to arrive at a unitary notion of force, thus avoiding the logical obscurity that lurked in the traditional formulation of mechanics.
1 Dec 2020
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Emilie Skulberg (University of Cambridge)
 
Visual representations of the space around black holes         

The image of the shadow of a black hole released in April 2019 became an icon in the span of hours. Although this image was historic, if we consider visual representations such as visualisations from simulations, diagrams, and artist impressions, the iconography of black holes dates back decades before the release of imaging based on observation. The first part of my presentation provides a brief overview of this history. The second part accounts for the production of imaging within the Event Horizon Telescope Collaboration, which was behind the April 2019 image. The presentation is based primarily on fieldwork where I have studied the work of the collaboration, an analysis of their publications targeting various audiences, and the study of a collection of black hole imaging from 1973 to 2000. 
8 Dec 2020
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Eleanor Knox (King's College London)

How to be a spacetime functionalist

There is increasing interest in a position that goes by the name of spacetime functionalism, and several authors emphasise the importance of functional reduction to the interpretation of spacetime theories. I will argue that, although thinking about functional reduction is apt in some cases, focussing on a Lewisian model of reduction misses important features of spacetime functionalism. I will illustrate this with cases from classical spacetime theories.
15 Dec 2020
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Gordon Belot (University of Michigan)

The Mach—Einstein Principle of 1917—1918
 
In 1917 and 1918 Einstein was working on relativistic cosmology and promoting and explaining general relativity in correspondence. During this period, he maintained that in general relativity the spacetime metric is fully determined by the distribution of matter. I’ll worry about what he means by this, whether it makes any sense, and whether any claim in the neighbourhood is true.
22 Dec 2020
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Sjang ten Hagen (University of Bonn)

Historical Methods in Nineteenth-Century Physics

The histories of the historical and the natural sciences have been written largely separately from one another. This is problematic, since it has obscured crucial instances of cross-fertilization between historical and natural-scientific research in the past. In my talk, I discuss a key example of such cross-fertilization: the use of historical methods in physics. In particular, I examine the historically focused work of two prominent German-speaking physicists from the nineteenth century: Johann Christian Poggendorff (1796–1877) and Ernst Mach (1838–1916). Both considered historiography to be a highly valuable tool for the physicist. Their motivations to use this tool, however, were very different. What were these motivations? What did Mach and Poggendorff’s historiography concretely entail? How were their results judged by other physicists, and by historians? And what, finally, does all this suggest about the general relationship between the historical and the natural sciences?
BREAK
12 Jan 2021
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Lydia Patton (Virginia Tech)

Expanding theory testing in general relativity: LIGO and parametrized theories

The multiple detections of gravitational waves by LIGO (the Laser Interferometer Gravitational-Wave Observatory), operated by Caltech and MIT, have been acclaimed as confirming Einstein's prediction, a century ago, that gravitational waves propagating as ripples in spacetime would be detected. Yunes and Pretorius (2009) investigate whether LIGO's template-based searches encode fundamental assumptions, especially the assumption that the background theory of general relativity is an accurate description of the phenomena detected in the search. They construct the parametrized post-Einsteinian (ppE) framework in response, which broadens those assumptions and allows for wider testing under more flexible assumptions. Their methods are consistent with work on confirmation and testing found in Carnap (1936), Hempel (1969), and Stein (1992, 1994), with the following principles in common: that confirmation is distinct from testing, and that, counterintuitively, revising a theory's formal basis can make it more broadly empirically testable. These views encourage a method according to which theories can be made abstract, to define families of general structures for the purpose of testing. With the development of the ppE framework and related approaches, multi-messenger astronomy is a catalyst for deep reasoning about the limits and potential of the theoretical framework of general relativity.

Based on:  https://www.sciencedirect.com/science/article/pii/S1355219818302089
19 Jan 2021
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Bernadette Lessel (Max Planck Institute for the History of Science, Berlin)

„I think I could make a report on quantization of gravitation much shorter than 30 minutes“ - Léon Rosenfeld and his understanding of the necessity of quantizing fields

Léon Rosenfeld is probably mostly known as devoted adherent and fierce defender of Niels Bohr’s interpretation of Quantum mechanics. But he also had had a past, where he had pioneered in a remarkable way in the area of quantization of gravitation, while he later sharply criticized this program altogether. In this talk we want to examine how this all goes together and in particular outline Rosenfeld's distinct view on the usage of mathematical methods in physical theory development.
26 Jan 2021
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Karim Thébault (University of Bristol)
Based on joint work with Sean Gryb (Groningen)

Poincaré, Dark Energy, and the Deadly Robots of Krikkit

Henri Poincaré, in a strangely neglected passage towards the end of his monumental essay on `Relative and Absolute Motion' (Science and Hypothesis, 1905 Chapter 7), appeals to the idea of a planet entirely secluded from the rest of the universe by clouds to argue that 'as long as nature has secrets' the distinction between constants of nature and constants of motion will remain 'highly arbitrary and always precarious' (p.87). 

To what extent do such arguments support a relationship between a scientist's epistemic access to different scales and the categorisation of constants? What are the implications of this view for modern cosmology, in particular the interpretation of the cosmological constant and the quantization of gravity? And what does any of this have to do with Robots?    

In this talk I will attempt to answer these and other related questions. 
2 Feb 2021
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James Read (Oxford University)
Based on joint work with Niels Linnemann (Rotman & Bremen)

On the null propagation of electromagnetic waves

Orthodoxy dictates that light propagates along null geodesics. Since at least the work of DeWitt and Brehme (1960), this orthodoxy has been questioned. Recently, Asenjo and Hojman (2017) have continued in this tradition, by solving Maxwell’s equations in spacetimes such as Gödel and Kerr. They argue that: (i) before the geometrical optics limit is taken, light in curved spacetimes need not propagate on null geodesics; (ii) sometimes, the geometrical optics limit cannot consistently be taken. In this talk, I expand upon (i), by considering the effects of including additional curvature coupling terms in Maxwell’s equations. I also argue that (ii) is false. Finally, I consider whether (as Asenjo and Hojman assume) the group velocity of light is properly associated with the signal velocity.
9 Feb 2021
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Siska de Baerdemaeker (Stockholm University)

Method-driven experiments and the search for dark matter
 
Since the discovery of dark matter, multiple experiments have been set up to detect dark matter particles through some other interaction than gravity--despite the fact that the only available evidence for dark matter's existence is through its gravitational effects. I show that the justifications for why these experiments should be able to detect dark matter take on a different structure than what is often the case in experimental practice. By illuminating this 'method-driven logic', I shed new light on questions surrounding complementarity and measurement robustness in context of dark matter research.
Philosophy of Dark Matter Workshop
This online workshop is being organised as part of the project "LHC, dark matter & gravity", and will take place on 29-30 March 2021 via Zoom. Click here for further info, incl. (free) registration. The times in the schedule below are in CEST.
Philosophy of Lambda Workshop
This online workshop will take place in June 2021. More info coming soon.
2019/20
History and Philosophy of Physics Research Seminar (Summer)

Time and Place:
Vertical Divider
Tuesdays from 4:15pm to 5:45pm CET.
Online via Zoom.
Zoom-links and weekly reminders are announced via hpp@listen.uni-bonn.de

Conveners:
Vertical Divider
Prof. Dr. Dennis Lehmkuhl
21.04.2020: Tushar Menon (Cambridge)
“Settlers of Cartan—how to be a true relationalist about General Relativity”
 
28.04.2020: Juliusz Doboszewski (Bonn)
“Humean supervenience and general relativity”

05.05.2020: Guido Bacciagaluppi (Utrecht)
"Better than Bohr: Grete Hermann and the Copenhagen Interpretation"
 
12.05.2020: Sean Gryb (Groningen)
"Relational Rotation"
 
26.05.2020: Robert DiSalle (Western University)
"Metaphysics and method of space-time theories: the contribution of conventionalism"
 
09.06.2020: Chris Wüthrich (Geneva)
"Spacetime functionalism from a realist perspective"
 
23.06.2020: Patrick Dürr (Oxford & Bonn)
"E Pluribus Unum - E Uno Pluralia: Minimal Bohmian Mechanics"
 
30.06.2020: Sam Fletcher (Minnesota)
"On Surplus Structure Arguments"
 
07.07.2020: Alex Blum (MPIWG Berlin)
"The birth of quantum mechanics from the spirit of radiation theory"
 
14.07.2020: Neil Dewar (MCMP, Munich)
"Duelling theories and dual theories”
History and Philosophy of Physics Research Seminar (Winter)

Time and Place:
Vertical Divider
Tuesdays from 4:15pm to 5:45pm CET.

Convener:
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Prof. Dr. Dennis Lehmkuhl
8.10.2019: Dennis Lehmkuhl (Bonn)
“Why integrated history and philosophy of physics? A case study in gravity”

15.10.2019: Patrick Dürr (Oxford and Bonn)
“Unweyling three Mysteries of Nordström Gravity”

22.10.2019: Erik Curiel (MCMP Munich)
“Kinematics, Dynamics, and the Structure of Theories”
 
5.11.2019: Jamee Elder (Notre Dame and Bonn)
“Black hole coalescence: models and measurement”
 
12.11.2019: Christian Röken (Bonn)
“An integral representation of the massive Dirac operator in the Kerr geometry in EF-type Coordinates”
 
19.11.2019: Taimara Passero  (Sao Paulo and Bonn)
"Some philosophical questions about the geometrization in General Relativity: approach from an image of nature and image of science"
 
26.11.2019: Juliusz Doboszewski (Bonn)
"Black to white hole bounces: an integrated history and philosophy of science perspective"
 
3.12.2019: Dominic Dold (Max Planck Institute for the History of Science)
“A unified approach to the relativistic and non-relativistic geodesic principle”
 
10.12.2019: Harvey Brown (Oxford)
“What I have learnt from the history of physics”

17.12.2019: Kian Salimkhani (Bonn)
“The dynamical approach to spin-2 gravity”
 
7.1.2020: Erhard Scholz (Wuppertal)
“Is integrable Weyl geometry useful in phyiscs?”
 
14.1.2020: Stephan Hartmann (MCMP Munich)
"Scientific Reasoning: The Bayesian Approach"
 
21.1.2020 Holger Lyre (Magdeburg)
“Structuralism about Parity. Handedness, mirror symmetry, and the metaphysics of space”
2018/19
Dark Matter & Modified Gravity Conference
Simplicities & Complexities Conference
History and Philosophy of Physics Research Seminar

Time and Place:
Vertical Divider
4:15pm to 5:45pm CET.

Convener:
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Prof. Dr. Dennis Lehmkuhl
20.12.2018: Erik Curiel (MCMP Munich & BHI Harvard)
"What Is the Einstein Field Equation, and Why Does It Matter for Quantum Gravity?"
 
10.01.2019: Patrick Dürr (Oxford)
“Against Fuctional Gravitational Energy"

02.04.2019: Tushar Menon (Oxford)
“Clocks and chronogeometry: Rotating spacetimes and the relativistic null hypothesis”
 
09.04.2019: Tilman Sauer (Mainz)
“The History of Distant Parallelism Revisited”
 
23.04.2019: Dennis Lehmkuhl (Bonn)
"The Einstein-Weyl correspondence and geodesic motion”
 
30.04.2019: Florian Boge (Wuppertal)
"Quantum Information vs. Epistemic Logic: An Analysis of the Frauchiger-Renner Theorem”
 
07.05.2019: Joshua Rosaler (Aachen)
"The Geometry of Reduction: Compound Reduction and Overlapping State Space Domains”
 
27.05.2019: Jeroen van Dongen (University of Amsterdam)
"History and Philosophy of the Black Hole Information Paradox”
 
04.06.2019: Carina Prunkl (Oxford)
"Boltzmann Brains and Simulations - rethinking the Skeptical Hypothesis”
 
18.06.2019: Radin Dardashti (Wuppertal)
"The Empirical Progress of Non-Empirical Science”
 
25.06.2019: Martin King (Bonn)
"The Rise of Model Independence in Particle Physics”
 
02.07.2019: Michael Stöltzner (South Carolina & Bonn)
"On the Emergence of Fluctuations”