Dark matter = modified gravity? Scrutinising the spacetime–matter distinction through the modified gravity/ dark matter lens

Martens, Niels C. M.; Lehmkuhl, Dennis

doi:10.1016/j.shpsb.2020.08.003

Cited by 22 publications

(30 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Just to the contrary, our relatively simple scalar field model is based on a natural, moderate generalization of Riemannian geometry; it does not need to impute artificially looking structures for the physical geometry of space-time. Its kinetic selfinteraction term tends to undermine the presently dominant dichotomy between spacetime and the dark sector, a bit like the superfluid approach does with regard to the DM-gravity dichotomy [37]. In contrast to the latter the energy momentum tensor of the scalar field resembles dark energy more than (dark) matter.…”

Section: A Series Of Open Questions Remainsmentioning

confidence: 96%

A scalar field inducing a non-metrical contribution to gravitational acceleration and a compatible add-on to light deflection

Scholz¹

2020

Gen Relativ Gravit

View full text Add to dashboard Cite

A scalar field model for explaining the anomalous acceleration and light deflection at galactic and cluster scales, without further dark matter, is presented. It is formulated in a scale covariant scalar tensor theory of gravity in the framework of integrable Weyl geometry and presupposes two different phases for the scalar field, like the superfluid approach of Berezhiani/Khoury. In low acceleration regimes of static gravitational fields (in the Einstein frame) with accordingly low values of the scalar field gradient, the scalar field Lagrangian combines a cubic kinetic term similar to the “a-quadratic” Lagrangian used in the first covariant generalization of MOND (RAQUAL) (Bekenstein and Milgrom in Astrophys J 286:7–14, 1984) and a second order derivative term introduced by Novello et al. in the context of a Weyl geometric approach to cosmology (Novello et al. in Int J Mod Phys D 1:641–677, 1993; de Oliveira et al. in Class Quantum Gravity 14(10):2833–2843, 1997). In varying with regard to $$\phi $$ ϕ the latter is variationally equivalent to a first order expression. The scalar field equation thus remains of order two. In the Einstein frame it assumes the form of a covariant generalization of the Milgrom equation known from the classical MOND approach in the deep MOND regime. It implies a corresponding “non-metrical” contribution to the acceleration of free fall trajectories. In contrast to pure RAQUAL, the second order derivative term of the Lagrangian leads to a non-negligible contribution to the energy momentum tensor and an add-on to the light deflection potential in beautiful agreement with the dynamics of low velocity trajectories. Although the model takes up important ingredients from the usual RAQUAL approach, it differs essentially from the latter.—In higher sectional curvature regions, respectively for higher accelerations in static fields, the scalar field Lagrangian consists of a Jordan–Brans–Dicke term with sufficiently high value of the JBD-constant to satisfy empirical constraints. Here the dynamics agrees effectively with the one of Einstein gravity.

show abstract

Section: A Series Of Open Questions Remainsmentioning

confidence: 96%

A scalar field inducing a non-metrical contribution to gravitational acceleration and a compatible add-on to light deflection

Scholz¹

2020

Gen Relativ Gravit

View full text Add to dashboard Cite

show abstract

“… 12 The same holds for the “Jesus interpretation” of the metric, recently advocated by Martens and Lehmkuhl ( 2020a ; 2020b ): according to it, the metric has a matter-spacetime hybrid nature. As a result, “vacuum” solutions are both purely spatiotemporal and purely gravitational-material.…”

mentioning

confidence: 89%

“…; cf. Martens & Lehmkuhl, 2020a , Sect. 3 for details): (MAT) For a field to be a matter field (rather than, say, a spacetime-geometric field), it’s essential that it possess an associated energy–stress tensor .…”

Section: The Super-substantivalist Case From Grmentioning

confidence: 99%

The general-relativistic case for super-substantivalism

Duerr

Calosi

2021

Synthese

View full text Add to dashboard Cite

Super-substantivalism (of the type we’ll consider) roughly comprises two core tenets: (1) the physical properties which we attribute to matter (e.g. charge or mass) can be attributed to spacetime directly, with no need for matter as an extraneous carrier “on top of” spacetime; (2) spacetime is more fundamental than (ontologically prior to) matter. In the present paper, we revisit a recent argument in favour of super-substantivalism, based on General Relativity. A critique is offered that highlights the difference between (various accounts of) fundamentality and (various forms of) ontological dependence. This affords a metaphysically more perspicuous view of what super-substantivalism’s tenets actually assert, and how it may be defended. We tentatively propose a re-formulation of the original argument that not only seems to apply to all classical physics, but also chimes with a standard interpretation of spacetime theories in the philosophy of physics.

show abstract

“…10 Since the authors conceive of the particle phase as consisting of axionlike particles-which, as bosons, naturally condense below a critical temperature-superfluid dark matter theory is arguably a version of one of the mainstream dark matter candidates. 11 [12,13,15,[18][19][20][21][22][23][24][25][26][27][28][29]. 12 Some examples are the small-scale challenges [31,32], the Bullet Cluster (which, despite usually being put forward as a smoking gun against modified gravity explanations of dark matter data, is potentially also problematic for ΛCDM) [33][34][35], and the tension between different measurements of the Hubble constant.…”

Section: Example Of a (Maximally) Thick Concept Of Dark Mattermentioning

confidence: 99%

“…11 Khoury (2016, 2015); Blanchet and Le Tiec (2008); Zhao (2008); Bruneton et al (2009); Li and Zhao (2009); Ho et al (2010Ho et al ( , 2011Ho et al ( , 2012; Cadoni et al (2018); Cadoni and Tuveri (2019); Scholz (2020); Skordis and Z lośnik (2020); Martens and Lehmkuhl (2020a);Ferreira (2021).…”

Section: Dark Mattermentioning

confidence: 99%

Dark Matter Realism

Martens

2021

Found Phys

View full text Add to dashboard Cite

According to the standard model of cosmology, $$\Lambda $$ Λ CDM, the mass-energy budget of the current stage of the universe is not dominated by the luminous matter that we are familiar with, but instead by some form of dark matter (and dark energy). It is thus tempting to adopt scientific realism about dark matter. However, there are barely any constraints on the myriad of possible properties of this entity—it is not even certain that it is a form of matter. In light of this underdetermination I advocate caution: we should not (yet) be dark matter realists. The “not(-yet)-realism” that I have in mind is different from Hacking’s (Philos Sci 56 (4), 555–581, 1989) anti-realism, in that it is semantic rather than epistemological. It also differs from the semantic anti-realism of logical empiricism, in that it is naturalistic, such that it may only be temporary and does not automatically apply to all other unobservables (or even just to all other astronomical unobservables, as with Hacking’s anti-realism). The argument is illustrated with the analogy of the much longer history of the concept of a gene, as the current state of the concept of dark matter resembles in some relevant ways that of the early concept of genes.

show abstract

Dark matter = modified gravity? Scrutinising the spacetime–matter distinction through the modified gravity/ dark matter lens

Cited by 22 publications

References 46 publications

A scalar field inducing a non-metrical contribution to gravitational acceleration and a compatible add-on to light deflection

A scalar field inducing a non-metrical contribution to gravitational acceleration and a compatible add-on to light deflection

The general-relativistic case for super-substantivalism

Dark Matter Realism

Contact Info

Product

Resources

About