## 2017-2018

9 June 2018, 10am-5pm, Caltech

**A Mini-Workshop on the Problem of Motion and Geodesic Theorems in GR**

10am: James Weatherall (Irvine), “The Motion of Small Bodies in Spacetime, or, Conservation, Inertia, and Spacetime Geometry”

11:30am: Coffee Break

11:45am: Dennis Lehmkuhl (Caltech), “The problem of motion: Einstein/Grommer and Thorne/Hartle compared”

1:15pm: Catered Lunch

2:30pm: Sam Fletcher (Minnesota), “When 2 Become 1: Approaches to the Problem of Motion”

4pm: Coffee Break

**Practical Information**

Location: The Einstein Papers Project, 363 S. Hill Ave, Pasadena, CA 91125

Local Organizer: Dennis Lehmkuhl

Parking: There is free street parking on Hill Avenue (during the weekend) and there is also a parking structure directly behind the EPP on Holliston Ave on S Holliston Ave.

5 May 2018, 3pm, LPS seminar room

**Joshua Norton (American University of Beirut), “The Hole Argument Against Everything”**

The Hole Argument was originally formulated by Einstein and it haunted him as he struggled to understand the meaning of spacetime coordinates in the context of the diffeomorphism invariance of general relativity. This argument has since been put to philosophical use by Earman and Norton (1987) to argue against a substantival conception of spacetime. In the present work I demonstrate how Earman and Norton’s Hole Argument can be extended to exclude everything and not merely substantival manifolds. These casualties of the hole demonstrate that the Hole Argument hinges essentially on our notion of determinism and not on the diffeomorphic freedom of general relativity.

Just as Earman and Norton argue that we should not let our metaphysics run roughshod over the structure of our physical theories, so I will argue that, in particular, we should not uncritically allow our metaphysics to dictate what our physical theories must determine. The central conviction which drives the arguments of this paper is that deterministic theories are not required to determine for future moments what they cannot determine for any present or past moments. I provide two arguments to the effect that a physically informed notion of determinism does not require general relativity to determine substantival facts. Consequently the Hole Argument cannot be used against substantival spacetime. The position that I advocate is an instance of “sophisticated determinism.”

A draft of Joshua’s paper can be found here.

24 February 2018, 3pm, LPS seminar room

**Lev Vaidman (Tel Aviv), “Defending the many-worlds interpretation of quantum mechanics”**

Starting from the premise that physics is deterministic and has no action at a distance, I will argue that the many-worlds interpretation is by far better than all existing alternatives. It keeps the physics part of the theory, the ontology of the universal wave function which incorporates all the worlds, very elegant. It is confirmed by experimental data with unprecedented precision. It provides a consistent connection with our experience. I will propose solutions for its alleged difficulties that the wave function in a high dimensional Hilbert space cannot correspond to our own experience of three spatial dimensions and that an experimentalist, who might have no ignorance of any detail of a quantum experiment, seems to have probabilities for different outcomes. The first difficulty is resolved by the observation that in every world the wave functions of all macroscopic objects are not entangled and thus defined in three dimension. The second is resolved by introducing the idea of probability of self-location of an observer in a particular world.

Please read Lev’s article before the meeting.

9 December 2017, 3pm, LPS seminar room

**David Wallace (USC), “Why Black Hole Information Loss is Paradoxical”**

I distinguish between two versions of the black hole information-loss paradox. The first arises from apparent failure of unitarity on the spacetime of a completely evaporating black hole, which appears to be non-globally-hyperbolic; this is the most commonly discussed version of the paradox in the foundational and semipopular literature, and the case for calling it `paradoxical’ is less than compelling. But the second arises from a clash between a fully-statistical-mechanical interpretation of black hole evaporation and the quantum-field-theoretic description used in derivations of the Hawking effect. This version of the paradox arises long before a black hole completely evaporates, seems to be the version that has played a central role in quantum gravity, and is genuinely paradoxical. After explicating the paradox, I discuss the implications of more recent work on AdS/CFT duality and on the `Firewall paradox’, and conclude that the paradox is if anything now sharper. The article is written at a (relatively) introductory level and does not assume advanced knowledge of quantum gravity.

Please read David’s preprint before the meeting.

4 November 2017, 3pm, LPS seminar room

**Marian Gilton (UCI), “Could Charge and Mass be Universal Properties?”**

There is a tradition in contemporary analytic metaphysics of looking to fundamental particle physics for an accurate list of universal properties. The central candidates for such properties are electric charge, color charge, and mass. Tim Maudlin has recently argued against a number of metaphysical theories within this tradition (Aristotelian and Platonic theories of universal properties, trope theory, the theory of natural sets, etc.) on the grounds that the general formalism of our current best fundamental physics–i.e., fiber bundles–precludes the notion of universal property used in these metaphysical theories. Consequently, Maudlin calls for a “wholesale revision” of the theory of universals. This paper argues, contra Maudlin, that the fiber bundle formalism does allow for the possibility of some universal properties, and thus a wholesale revision of this metaphysical theory is not yet warranted.

Please read Marian’s draft manuscript in preparation for the meeting.