Background Independence, Diffeomorphism Invariance, and the Meaning of Coordinates

Diffeomorphism invariance is sometimes taken to be a criterion of background independence. This claim is commonly accompanied by a second, that the genuine physical magnitudes (the "observables") of background-independent theories and those of background-dependent (non-diffeomorphism-invariant) theories are essentially different in nature. I argue against both claims. Background-dependent theories can be formulated in a diffeomorphism-invariant manner. This suggests that the nature of the physical magnitudes of relevantly analogous theories (one background free, the other background dependent) is essentially the same. The temptation to think otherwise stems from a misunderstanding of the meaning of spacetime coordinates in background-dependent theories.Comment: 42 page

The origin of the spacetime metric: Bell's `Lorentzian pedagogy' and its significance in general relativity

The purpose of this paper is to evaluate the `Lorentzian pedagogy' defended by J.S. Bell in his essay ``How to teach special relativity'', and to explore its consistency with Einstein's thinking from 1905 to 1952. Some remarks are also made in this context on Weyl's philosophy of relativity and his 1918 gauge theory. Finally, it is argued that the Lorentzian pedagogy - which stresses the important connection between kinematics and dynamics - clarifies the role of rods and clocks in general relativity.Comment: To be published in ``Physics Meets Philosophy at the Planck Length'', C. Callender and N. Huggett (eds.), Cambridge University Press (1999). 22 pages, no figures, LaTeX, uses harvard.sty; 3 references added, typos corrected and minor changes to conten

The Hole Argument

This paper reviews the hole argument as an argument against spacetime substantivalism. After a careful presentation of the argument itself, I critically review possible responses

The Hole Argument

This paper reviews the hole argument as an argument against spacetime substantivalism. After a careful presentation of the argument itself, I critically review possible responses

Fundamentality and the Dynamical Approach to Relativity

I argue that notions of relative fundamentality need to be invoked if there is to be something substantive at stake in the debate between proponents of Harvey Brown's dynamical approach to relativity and defenders of a more traditional interpretation of spacetime. I will review some problems that stand in the way of the advocate of the dynamical approach making good on their claim that dynamical symmetries are more fundamental than spacetime symmetries

First-class constraints generate gauge transformations in electromagnetism (reply to Pitts)

Brian Pitts has recently claimed to show via straightforward calculation that, at least in the case of Hamiltonian electromagnetism, an arbitrary first-class constraint ``generates not a gauge transformation, but a bad physical change'' (Annals of Physics 351 (2014) pp.382--406; http://philsci-archive.pitt.edu/11015/). We show, via a straightforward calculation, that a transformation generated by an arbitrary first-class constraint relates gauge-equivalent phase space points, vindicating orthodoxy. Pitts, however, is primarily concerned with transformations of entire histories, rather than of instantaneous states. We show that, even in this context, a transformation generated by an arbitrary first-class constraint is also a gauge transformation, once the empirically observed electric field is correctly identified via its dynamical interactions with charge, and not simply given stipulatively as a certain combination of the potential and its derivatives

On the Mathematics and Metaphysics of the Hole Argument

We make some remarks on the mathematics and metaphysics of the hole argument, in response to a recent article in this journal by Weatherall ([2018]). Broadly speaking, we defend the mainstream philosophical literature from the claim that correct usage of the mathematics of general relativity `blocks' the argument

On the Mathematics and Metaphysics of the Hole Argument

We make some remarks on the mathematics and metaphysics of the hole argument, in response to a recent article in this journal by Weatherall ([2018]). Broadly speaking, we defend the mainstream philosophical literature from the claim that correct usage of the mathematics of general relativity `blocks' the argument

Changing home and workplace in Victorian London : the life of Henry Jaques shirtmaker.

The paper uses unusually rich evidence from a manuscript life history written in 1901 from personal diaries to explore the changing relationship between home and workplace in Victorian London. The life history of Henry Jaques demonstrates the way in which decisions about employment and residence were related both to each other and to stages of the family life course. The uncertainty of work, lack of income to support a growing family, rising aspirations, the constant threat of illness, the ease of moving between rented property, close ties between home and workplace, the stresses produced by home working, and the attractions of suburbanization all interacted to shape the residential and employment history of Jaques and his family. The themes exemplified by this detailed life history were also relevant to many other people. Evidence collected from a large-scale project on lifetime residential histories is used to place the experiences of Henry Jaques in a broader context, and to show how they related to the changing social and economic structure of Victorian London

Gene Therapy for Glaucoma by Ciliary Body Aquaporin 1 disruption using CRISPR-Cas9

Glaucoma is a common cause of blindness, yet current therapeutic options are imperfect. Clinical trials have invariably shown that reduction in intraocular pressure (IOP) regardless of disease subtype prevents visual loss. Reducing ciliary body aqueous humor production can lower IOP, and the adeno-associated virus ShH10 serotype was identified as able to transduce mouse ciliary body epithelium following intravitreal injection. Using ShH10 to deliver a single vector CRISPR-Cas9 system disrupting Aquaporin 1 resulted in reduced IOP in treated eyes (10.4 ± 2.4 mm Hg) compared with control (13.2 ± 2.0 mm Hg) or non-injected eyes (13.1 ± 2.8 mm Hg; p < 0.001; n = 12). Editing in the aquaporin 1 gene could be detected in ciliary body, and no off-target increases in corneal or retinal thickness were identified. In experimental mouse models of corticosteroid and microbead-induced ocular hypertension, IOP could be reduced to prevent ganglion cell loss (32 ± 4 /mm2) compared with untreated eyes (25 ± 5/mm2; p < 0.01). ShH10 could transduce human ciliary body from post-mortem donor eyes in ex vivo culture with indel formation detectable in the Aquaporin 1 locus. Clinical translation of this approach to patients with glaucoma may permit long-term reduction of IOP following a single injection