# Breakdown of the Newton-Einstein Standard Gravity at Low Acceleration in Internal Dynamics of Wide Binary Stars

**Authors:** Kyu-Hyun Chae  
**arXiv:** [2305.04613](https://arxiv.org/abs/2305.04613)  
**Date:** 2023-05-08  
**Summary page:** https://www.summarizepaper.com/en/paper/2305.04613v1/

## Key points

- Researchers have discovered a gravitational anomaly in the internal dynamics of wide binary stars at weak gravitational acceleration.
- They used implicit high-order multiplicities and calibrated the multiplicity fraction to align the internal motions of binaries statistically with Newtonian dynamics at higher accelerations.
- Data from the Gaia EDR3 database was used to analyze observed sky-projected motions and separation using a Monte Carlo method.
- The empirical acceleration relation at weak gravitational accelerations below $10^{-9}$ m s$^{-2}$ deviates systematically from what is expected based on Newtonian dynamics.
- The researchers measured a gravitational anomaly parameter $\delta_{\rm{obs-newt}}$, which represented the difference between observed acceleration and the Newtonian prediction.
- At $g_{\rm{N}} \approx 10^{-8.91}$ and $10^{-10.15}$ m s$^{-2}$, $\delta_{\rm{obs-newt}}$ was found to be equal to $0.034\pm 0.007$ and $0.109\pm 0.013$, respectively, with both deviations in the same direction and significant at a level of $10\sigma$.
- At $g_{\rm{N}} = 10^{-10.15}$ m s$^{-2}$, the observed to Newtonian predicted acceleration ratio was equal to $1.43\pm 0.06$, aligning with predictions from alternative theories like AQUAL for kinematic accelerations in circular orbits under the Galactic external field.
- This study provides compelling evidence for a breakdown of standard gravity at weak gravitational accelerations based on observations of wide binary stars, challenging our current understanding of gravity.
- Further research is needed to fully understand its implications and potential impact on our understanding fundamental physics.

## Summary

In a recent study, researchers have discovered a gravitational anomaly at weak gravitational acceleration in the internal dynamics of wide binary stars. To investigate the dynamics of these systems, they utilized implicit high-order multiplicities and calibrated the multiplicity fraction to ensure that the internal motions of binaries align statistically with Newtonian dynamics at higher accelerations. Data from the Gaia EDR3 database was used to deproject observed sky-projected motions and separation into three-dimensional relative velocity and separation using a Monte Carlo method. This enabled them to compare the statistical relation between Newtonian acceleration ($g_{\rm{N}} \equiv GM/r^2$, where $M$ is the total mass of the binary system) and kinematic acceleration ($g \equiv v^2/r$) with what is predicted by Newtonian dynamics. The empirical acceleration relation at weak gravitational accelerations below $10^{-9}$ m s$^{-2}$ was found to systematically deviate from what is expected based on Newtonian dynamics. The researchers measured a gravitational anomaly parameter $\delta_{\rm{obs-newt}}$, representing the difference between observed acceleration at $g_{\rm{N}}$ and the Newtonian prediction. They found that $\delta_{\rm{obs-newt}}$ was equal to $0.034\pm 0.007$ and $0.109\pm 0.013$ at $g_{\rm{N}} \approx 10^{-8.91}$ and $10^{-10.15}$ m s$^{-2}$, respectively, based on their analysis of a main sample consisting of 26,615 wide binaries within 200 pc - both deviations were in the same direction and represented a significance level of $10\sigma$. At $g_{\rm{N}} = 10^{-10.15}$ m s$^{-2}$, they found that the observed to Newtonian predicted acceleration ratio was equal to $1.43\pm 0.06$. This systematic deviation aligns with the boost factor predicted by the AQUAL theory for kinematic accelerations in circular orbits under the Galactic external field - providing strong evidence for a breakdown of standard gravity at weak accelerations beyond what can be explained by current theories of gravity alone. Overall, this study provides compelling evidence for a breakdown of standard gravity at weak gravitational accelerations based on observations of wide binary stars - challenging our current understanding of gravity and opening up new avenues for exploring alternative theories that can explain these anomalies. Further research is needed to fully understand its implications and potential impact on our understanding fundamental physics.