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jb manchak

@manchak.bsky.social

philosopher of physics at uc irvine. https://sites.socsci.uci.edu/~jmanchak/

66 Posts208 Follower152 Folgt
jb manchak@manchak.bsky.social · 4mo ago

Let's say a *Buddha spacetime* (impermanence at every event) is one with no local Killing fields. A *Heraclitus spacetime* (can't step into the same river twice) is one with no local isometries between any distinct points. Theorem. Every Heraclitus spacetime is Buddha but not the other way around.

jb manchak@manchak.bsky.social · 4mo ago

Not sure who needs to hear this today but determinism is not a mysterious metaphysical notion. If you or a loved one are struggling with haecceities, hang in there and read this paper. You got this! (new work with Hans Halvorson and @jamesowenweatherall.com) onlinelibrary.wiley.com/doi/10.1111/...

Deterministic Theories

Determinism is (roughly) the thesis that the past determines the future. But efforts to define it precisely have exposed deep methodological disagreements. Standard possible-worlds formulations of de...

onlinelibrary.wiley.com

jb manchak@manchak.bsky.social · 11mo ago

What happens when you remove a carefully chosen Cantor set from time-rolled Minkowski spacetime? You settle a extendibility question posed by Bob Geroch 55 years ago!

PhilSci-Archive@philsci-archive.bsky.social · 11mo ago

New on the Archive: Andréka, Hajnal and Madarász, Judit X. and Manchak, JB and Németi, István and Székely, Gergely (2025) An Extendible Spacetime Without Closed Timelike Curves Whose Every Extension Contains Closed Timelike Curves. [Preprint] https://philsci-archive.pitt.edu/27030/

jb manchak@manchak.bsky.social · 11mo ago

Had an absolute blast writing this paper with Thomas, Hans, and @jamesowenweatherall.com! GR turns out to be way more deterministic than previously appreciated. The past determines the future not only up to isomorphism but up to *unique* isomorphism! 🤯

British Journal for the Philosophy of Science@thebjps.bsky.social · 11mo ago

Just accepted: Determinism and Asymmetry in General Relativity – J B Manchak, Thomas Barrett, Hans Halvorson & James Weatherall Abstract in alt text or read the paper here: www.journals.uchicago.edu/doi/10.1086/... #philsci #philsky

ABSTRACT. This article concerns the question of which collections of general relativistic spacetimes are deterministic relative to which definitions. We begin by considering a series of three definitions of increasing strength due to Belot. The strongest of these definitions is particularly interesting for spacetime theories because it involves an asymmetry condition called `rigidity' that has been studied previously in a different context by Geroch. We show how Belot's strongest definition is connected to a formal result emphasized by Weatherall. We then go on to explore other (stronger) asymmetry conditions that give rise to other (stronger) forms of determinism. We introduce a number of definitions of this type and clarify the relationships between them and the three considered by Belot. We show that there are collections of general relativistic spacetimes that satisfy much stronger forms of determinism than previously known. We also highlight a number of open questions.
jb manchak@manchak.bsky.social · last yr.

It is sometimes claimed that the "privileged coordinates" of geometric model (e.g. a relativistic spacetime) encode its "structure". In a paper just out in Philosophy of Science (open access), Thomas Barrett and I explore the limitations of this idea... www.cambridge.org/core/journal...

What Do Privileged Coordinates Tell Us about Structure? | Philosophy of Science | Cambridge Core

What Do Privileged Coordinates Tell Us about Structure? - Volume 92 Issue 3

cambridge.org

Jim Weatherall@jamesowenweatherall.com · 2y ago

#philsky #philsci Videos from the workshop on Symmetry and Structure that Clara Bradley and I organized in Irvine in September 2023 are now available online. Some very interesting stuff there! Enjoy! jamesowenweatherall.com/symmetry-and... youtube.com/playlist?lis...

Symmetry and Structure, UCI Workshop October 2023 - YouTube

Talks from the workshop "Symmetry and Structure", hosted by the Department of Logic and Philosophy of Science at the University of California, Irvine. 27-28 ...

youtube.com

jb manchak@manchak.bsky.social · 2y ago

New paper "On Privileged Coordinates and Kleinian Methods" just published online at Erkenntnis (joint work with Thomas Barrett). We investigate senses in which the "privileged coordinates" of a geometric space might have significance. link.springer.com/article/10.1...

On Privileged Coordinates and Kleinian Methods - Erkenntnis

This paper examines two ways in which the ‘privileged coordinates’ of a geometric space might have significance. First, the structure of the space might be ‘determined by its privileged coordinates’. ...

link.springer.com