# Action at a Distance Can Explain Dark Matter, Physicists Show Source: https://www.youtube.com/watch?v=1WgNON-OWAc Recap page: https://rapidrecap.app/video/1WgNON-OWAc Generated: 2026-01-08T16:55:30.585+00:00 --- ## 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. ![Screenshot at 00:15: The video displays a slide with the text 'Dark Matter FALSE' stamped over an image of a telescope under the Milky Way, visually signaling the presenter's skepticism toward the standard Dark Matter hypothesis.](https://ss.rapidrecap.app/screens/1WgNON-OWAc/00-00-15.jpg) **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. ## Detailed Analysis The video discusses the persistent problem of dark matter, which physicists have searched for decades to find, noting that it constitutes about 24% of the universe's energy density according to the standard cosmological model (which includes 71.4% Dark Energy and 4.6% Normal Matter, as shown in a pie chart around 2:34). The presenter highlights that both Newtonian gravity (instantaneous 'action at a distance') and Einstein's General Relativity (GR, where curvature changes propagate at the speed of light) are fundamentally local theories. The new paper by Deffayet and Woodard proposes a theory of Nonlocal Gravity that provides a consistent description for both cosmological observations (like galaxy clusters, which usually require dark matter) and smaller-scale galaxy rotation curves, where Modified Newtonian Dynamics (MOND) has historically performed better than the standard dark matter model. The authors claim their nonlocal modification of gravity explains these phenomena without introducing any new matter. The presenter notes that while the mathematical framework seems sound, the theory's complexity (involving differential equations) and its unverified status (not peer-reviewed, as shown by a stamp at 2:34) leads her to rate it relatively low (5/10) on her 'Bullshit Meter,' concluding that dark matter remains the standard explanation despite these alternative proposals. ### Dark Matter Problem - Standard model requires 24% Dark Matter to explain galaxy rotation curves and cluster dynamics - The proposed Nonlocal Gravity theory aims to explain these observations without new matter - Standard theories (Newtonian and GR) are local, but the proposed theory is nonlocal. ### MOND vs. Dark Matter - MOND explains galaxy rotation curves well but fails for galaxy clusters - Dark Matter successfully explains both, but remains undetected - The new theory interpolates between MOND's success on galaxy scales and GR's success on cosmological scales. ### Paper Assessment - The paper by Deffayet & Woodard (arXiv:2512.10513) is not yet peer-reviewed - The presenter gives it a 5/10 on her 'Bullshit Meter' due to lack of peer review and mathematical difficulty in handling the full differential equations. ### Brilliant.org Promotion - The video promotes Brilliant.org, offering viewers a 30-day free trial and 20% off an annual subscription using the link brilliant.org/Sabine. ![Screenshot at 00:00: Sabine Hossenfelder introduces the topic of what the universe is made of, specifically questioning the existence of Dark Matter.](https://ss.rapidrecap.app/screens/1WgNON-OWAc/00-00-00.jpg) ![Screenshot at 00:15: A visual graphic labels the concept of Dark Matter as 'FALSE' over an image of a telescope, emphasizing the video's skeptical stance on the conventional explanation.](https://ss.rapidrecap.app/screens/1WgNON-OWAc/00-00-15.jpg) ![Screenshot at 01:34: Einstein's concept of 'Action at a Distance' \(which he disliked regarding Newtonian gravity\) is contrasted with the locality principle in General Relativity.](https://ss.rapidrecap.app/screens/1WgNON-OWAc/00-01-34.jpg) ![Screenshot at 02:34: A pie chart illustrates the standard cosmological composition: 71.4% Dark Energy, 24% Dark Matter, and 4.6% Normal Matter, highlighting the dominance of unknown components.](https://ss.rapidrecap.app/screens/1WgNON-OWAc/00-02-34.jpg) ![Screenshot at 04:54: A man overwhelmed by complex equations on a blackboard illustrates the difficulty physicists face when trying to reconcile gravity with other theories.](https://ss.rapidrecap.app/screens/1WgNON-OWAc/00-04-54.jpg)