Directly testing gravity with Proxima Centauri

Banik, Indranil; Kroupa, Pavel

doi:10.1093/mnras/stz1379

Cited by 12 publications

(12 citation statements)

References 77 publications

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“…A high precision astrometry mission with an extended baseline of 10 years and a precision of 0.5 μas could measure the wide binary orbit of Proxima Centauri around Alpha Centauri A and B to distinguish between Newtonian gravity and Milgromian dynamics (MOND). The separation between Proxima Centauri and the Alpha Centauri system suggests orbital acceleration that is significantly less than the MOND acceleration constant a 0 ∼ 1.2 × 10 −10 m/s 2 [14]. It would be the first direct measurement of the departure from Newtonian gravity in the very weak field limit, as expected in MOND, and the results could have profound implications for fundamental physics.…”

Section: Directly Testing Gravitymentioning

confidence: 74%

Faint objects in motion: the new frontier of high precision astrometry

et al. 2021

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Sky survey telescopes and powerful targeted telescopes play complementary roles in astronomy. In order to investigate the nature and characteristics of the motions of very faint objects, a flexibly-pointed instrument capable of high astrometric accuracy is an ideal complement to current astrometric surveys and a unique tool for precision astrophysics. Such a space-based mission will push the frontier of precision astrometry from evidence of Earth-mass habitable worlds around the nearest stars, to distant Milky Way objects, and out to the Local Group of galaxies. As we enter the era of the James Webb Space Telescope and the new ground-based, adaptive-optics-enabled giant telescopes, by obtaining these high precision measurements on key objects that Gaia could not reach, a mission that focuses on high precision astrometry science can consolidate our theoretical understanding of the local Universe, enable extrapolation of physical processes to remote redshifts, and derive a much more consistent picture of cosmological evolution and the likely fate of our cosmos. Already several missions have been proposed to address the science case of faint objects in motion using high precision astrometry missions: NEAT proposed for the ESA M3 opportunity, micro-NEAT for the S1 opportunity, and Theia for the M4 and M5 opportunities. Additional new mission configurations adapted with technological innovations could be envisioned to pursue accurate measurements of these extremely small motions. The goal of this White Paper is to address the fundamental science questions that are at stake when we focus on the motions of faint sky objects and to briefly review instrumentation and mission profiles.

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Section: Directly Testing Gravitymentioning

confidence: 74%

Faint objects in motion: the new frontier of high precision astrometry

et al. 2021

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“…Accurate observations of our nearest wide binary should allow for a decisive test of the low-acceleration gravity law (Banik & Kroupa 2019a). By considering Proxima Centauri as a test particle subject to the combined gravity of the much more massive α Centauri A and B, those authors showed that its orbital acceleration should be 0.60 a 0 in Newtonian gravity but 0.87 a 0 in MOND, with a similar expected direction.…”

Section: Using the Acceleration Of Proxima Centaurimentioning

confidence: 91%

From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity

Banik,

Zhao

2021

Preprint

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Astronomical observations reveal a major deficiency in our understanding of physics − the detectable mass is insufficient to explain the observed motions in a huge variety of systems given our current understanding of gravity, Einstein's General theory of Relativity (GR). This missing gravity problem may indicate a breakdown of GR at low accelerations, as posited by Milgromian dynamics (MOND). We review the MOND theory and its consequences, including in a cosmological context where we advocate a hybrid approach involving light sterile neutrinos to address MOND's cluster-scale issues. We then test the novel predictions of MOND using evidence from galaxies, galaxy groups, galaxy clusters, and the large scale structure of the Universe. We also consider whether the standard cosmological paradigm (ΛCDM) can explain the observations, and review several previously published highly significant falsifications of it. Our overall assessment considers both the extent to which the data agree with each theory and how much flexibility each has when accommodating the data, with the gold standard being a clear a priori prediction not informed by the data in question. We also consider some future tests, including on scales much smaller than galaxies. Our conclusion is that MOND is favoured by a wealth of data across a huge range of astrophysical scales, ranging from the kpc scales of galactic bars to the Gpc scale of the local supervoid and the Hubble tension, which is alleviated in MOND through enhanced cosmic variance.

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“…Note, importantly, that velocities remain the same under spacetime scaling. 4. As an additional, small-print tenet we add, in deference to parsimony, the requirement that no other new dimensional constants appear in MOND.…”

Section: A Mond -Basic Tenetsmentioning

confidence: 99%

MOND vs. dark matter in light of historical parallels

Milgrom

2020

Studies in History and Philosophy of Science Part B: Studies in

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MOND is a paradigm that contends to account for the mass discrepancies in the Universe without invoking 'dark' components, such as 'dark matter' and 'dark energy'. It does so by supplanting Newtonian dynamics and General Relativity, departing from them at very low accelerations. Having in mind readers who are historians and philosophers of science, as well as physicists and astronomers, I describe in this review the main aspects of MOND -its statement, its basic tenets, its main predictions, and the tests of these predictions -contrasting it with the dark-matter paradigm. I then discuss possible wider ramifications of MOND, for example the potential significance of the MOND constant, a0, with possible implications for the roots of MOND in cosmology. Along the way I point to parallels with several historical instances of nascent paradigms. In particular, with the emergence of the Copernican world picture, that of quantum physics, and that of relativity, as regards their initial advent, their development, their schematic structure, and their ramifications. For example, the interplay between theories and their corollary laws, and the centrality of a new constant with converging values as deduced from seemingly unrelated manifestations of these laws. I demonstrate how MOND has already unearthed a number of unsuspected laws of galactic dynamics (to which, indeed, a0 is central) predicting them a priori, and leading to their subsequent verification. I parallel the struggle of the new with the old paradigms, and the appearance of hybrid paradigms at such times of struggle. I also try to identify in the history of those established paradigms a stage that can be likened to that of MOND today.

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Directly testing gravity with Proxima Centauri

Cited by 12 publications

References 77 publications

Faint objects in motion: the new frontier of high precision astrometry

Faint objects in motion: the new frontier of high precision astrometry

From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity

MOND vs. dark matter in light of historical parallels

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