Periodic Reporting for period 1 - COSMO-MASTER (Philosophy of COSMOlogy: Matter And SpaceTime ERadicated)
Periodo di rendicontazione: 2023-04-01 al 2025-09-30
Our most basic, fundamental assumptions are often the ones that get scrutinised the least. This very much holds true for the primary ontological and conceptual distinction that underlies much of physics, philosophy of physics and metaphysics: the idea that all entities and structures in our universe are to be categorised and conceptualized as either space (or, in modern physics, spacetime) or matter, never both, never neither. Everything must be either the “container” or the “contained”. Although this strict conceptual dichotomy did make a lot of sense in the context of our pre-20th-century worldview, the COSMO-MASTER project contends that it is no longer tenable, and even a hindrance to further progress. More precisely, each of the main ingredients—dark matter, inflation, dark energy, black holes and general relativity—of our highly-successful and well-established standard model of cosmology that was developed over the course of the 20th century puts pressure on the outdated Newtonian idea that the space(time) and matter concepts can and should be strictly distinguished. A systematic interdisciplinary analysis of the extent to which this dichotomy breaks down will have profound consequences for various debates in the philosophy of physics and metaphysics (e.g. undermining the substantivalismꟷrelationalism debate about the metaphysics of spacetime, and providing novel opportunities to reassess and advance debates regarding conventionalism, scientific realism and scientific guiding principles) as well as for theory development and community interaction in cosmology, and physics more broadly. Far from being an unwelcome babel, a conceptual undoing, giving up the spacetimeꟷmatter distinction will provide guidance as to which traditional debates become moot and which novel avenues open up.
Our analysis so far has focused on three of the case studies: dark energy, inflation, and black holes. Since inflation and dark energy share interesting similarities—they are each responsible for the accelerated expansion of our universe, in the early and current universe, respectively—our first realisation was that many of the COSMO-MASTER questions were best posed in the broader framework of scalar-tensor theories, of which various mainstream examples of inflation and dark energy are specific instances. Our results suggest that a strict spacetime-matter dichotomy indeed does not apply to the scalar field in these theories, since this categorisation differs across two perspectives (the so-called Jordan and Einstein frames) which are supposed to be mere redescriptions of the same underlying (meta)physics. One interpretational option is to consider the spacetime and matter categories to be a matter of mere convention, rather than objective matters of fact. We find the most natural conclusion to be to give up on those categories altogether, at least in this context. An unexpected positive result is that the conceptual category of gravity does still apply to the scalar field.
Further research on dark energy specifically suggests that it may also be a mere matter of convention whether one understands the simplest form of dark energy, i.e. a cosmological constant, as a constant of nature or a specific form of matter. Moreover, it seems that the explanation of the accelerated expansion of the universe due to dark energy could be considered either a gravitational/spatiotemporal explanation or a matter-based explanation. This undermines the debate between substantivalism (spacetime is fundamental) and relationalism (matter is fundamental).
We have distinguished five possible interpretations of the mass of black holes. A detailed analysis of one specific interpretation shows that the mass—typically the hallmark of matter—of a black hole is also inherently spacetime-like. A metaphysical analysis of all interpretations (qua substantivalism versus relationalism) seems to corroborate this blurring of the spacetime-matter distinction.
In sum, the preliminary results on these three case studies confirm our main hypothesis, with as unexpected bonus result that the gravity category does seem to remain viable in the context of scalar-tensor theories.
A more general goal behind the COSMO-MASTER project was to firmly establish philosophy of astronomy & cosmology within the EU. The ERC Starting Grant has allowed us to create the Utrecht Philosophy of Astronomy & Cosmology research group (uu.nl/upac) which is already one of the largest philosophy of physics groups in the EU. The weekly group meetings, our almost-weekly colloquium, two international conferences, and three workshops so far, have attracted a vibrant, interdisciplinary, international audience. The team has moreover played a leading role in consolidating history & philosophy of physics in the Netherlands (hpp-nl.nl).
Further research on dark energy specifically suggests that it may also be a mere matter of convention whether one understands the simplest form of dark energy, i.e. a cosmological constant, as a constant of nature or a specific form of matter. Moreover, it seems that the explanation of the accelerated expansion of the universe due to dark energy could be considered either a gravitational/spatiotemporal explanation or a matter-based explanation. This undermines the debate between substantivalism (spacetime is fundamental) and relationalism (matter is fundamental).
We have distinguished five possible interpretations of the mass of black holes. A detailed analysis of one specific interpretation shows that the mass—typically the hallmark of matter—of a black hole is also inherently spacetime-like. A metaphysical analysis of all interpretations (qua substantivalism versus relationalism) seems to corroborate this blurring of the spacetime-matter distinction.
In sum, the preliminary results on these three case studies confirm our main hypothesis, with as unexpected bonus result that the gravity category does seem to remain viable in the context of scalar-tensor theories.
A more general goal behind the COSMO-MASTER project was to firmly establish philosophy of astronomy & cosmology within the EU. The ERC Starting Grant has allowed us to create the Utrecht Philosophy of Astronomy & Cosmology research group (uu.nl/upac) which is already one of the largest philosophy of physics groups in the EU. The weekly group meetings, our almost-weekly colloquium, two international conferences, and three workshops so far, have attracted a vibrant, interdisciplinary, international audience. The team has moreover played a leading role in consolidating history & philosophy of physics in the Netherlands (hpp-nl.nl).
The state of the art is a firmly entrenched, rigid conceptual dichotomy between spacetime and matter. The preliminary analyses of three of the case studies confirm our main hypothesis that this orthodoxy is outdated. The main unexpected preliminary result is that gravity, as a conceptual category, may remain viable in some contexts, if one decouples it from the ontological and conceptual category of spacetime.