Action at a Distance Can Explain Dark Matter, Physicists Show

Quick Overview

Physicists C. Deffayet and R. P. Woodard proposed a new theory of Nonlocal Gravity that successfully explains observations traditionally attributed to Dark Matter, such as galaxy rotation curves and galaxy cluster dynamics, without requiring the introduction of any new, unobserved matter component.

Key Points: The standard model relies on Dark Matter (24% of the universe's mass-energy density) to explain galactic rotation curves and galaxy cluster dynamics, but this component remains undetected. Deffayet and Woodard propose a theory of Nonlocal Gravity that interpolates between cosmology and gravitationally bound systems, explaining observations without invoking Dark Matter. Newtonian gravity is local (instantaneous interaction regardless of distance), which Newton himself disliked, but Einstein's General Relativity (GR) is also local, meaning spacetime curvature changes propagate at the speed of light. The proposed Nonlocal Gravity theory differs from GR by allowing non-local interactions, which successfully explains galaxy rotation curves (where MOND works) and galaxy cluster dynamics (where Dark Matter is usually required). The authors assign the paper a low score (5/10) on their 'Bullshit Meter' because the theory, while mathematically sound according to the presenter, has not yet undergone peer review and is difficult to test practically. The presentation concludes by promoting Brilliant.org, offering viewers 20% off an annual subscription after a 30-day free trial using the link brilliant.org/Sabine.

Context: This video segment from 'Science News with Sabine Hossenfelder' critiques a recent, non-peer-reviewed paper by physicists C. Deffayet and R. P. Woodard. The paper suggests that the gravitational anomalies currently explained by postulating the existence of Dark Matter (which comprises about 24% of the universe's energy density) might instead be explained by a modified theory of gravity called Nonlocal Gravity, which bypasses the need for dark matter particles.