Mastodawn

The Atacama Cosmology Telescope - A Test of the #GravitationalForce Law on Cosmological Scales Using the Kinematic Sunyaev-Zeldovich Effect: https://arxiv.org/abs/2604.14327 -> Gravity follows Newton and Einstein’s rules, even at cosmic scales: https://penntoday.upenn.edu/news/gravity-follows-newton-and-einsteins-rules-even-cosmic-scales - by tracking galaxy clusters hundreds of millions of lightyears apart, Penn physicist Patricio Gallardo and collaborators find that the laws of gravity written by Newton and Einstein still hold, leaving little doubt that invisible dark matter exists.

The Atacama Cosmology Telescope: A Test of the Gravitational Force Law on Cosmological Scales Using the Kinematic Sunyaev-Zeldovich Effect

The mean pairwise velocity of massive halos reflects the gravitational force law on cosmic scales. We combine cosmic microwave background intensity maps from the Atacama Cosmology Telescope and a galaxy catalog from the Sloan Digital Sky Survey to estimate the mean pairwise velocity using the kinematic Sunyaev-Zeldovich (kSZ) effect. On scales from 30 -- 230 megaparsecs, we constrain the gravitational acceleration between pairs of halos at separation $r$ to be $g\propto 1/r^n$ with $n=2.1\pm 0.3$, which is consistent with Newtonian gravity in an expanding spacetime (\textit{i.e.}, the standard $Λ$CDM model). This constraint shows agreement with an inverse quadratic radial dependence over the large distances separating galaxy halos, as expected in standard cosmology. Upcoming surveys have the potential to rule out $n = 1$ at $10σ$ significance. Our results establish the kSZ effect as a powerful tool for testing gravity on cosmological scales.

arXiv.org

PhET Sims Apr 22, 2025

Our Kepler's Laws simulation lets students visualize “swept area of a planet’s orbit” and its relationship with equal time intervals in the context of Kepler’s second Law.
https://phet.colorado.edu/en/simulations/keplers-laws
#Astronomy #GravitationalForce #AvailableInPhETStudio

Kepler's Laws

Interact with the variables to discover how planetary objects moves in elliptical orbits, and the other characteristics of these orbits described by the three Kepler’s Laws. Connect Astronomy with Math, by experimenting with ellipses, areas, and graphs.

PhET

PhET Sims Feb 25, 2025

How does gravity control the motion of our solar system? Move the Sun, Earth, Moon and Space Station to see how it affects their gravitational forces and orbital paths in Gravity and Orbits https://phet.colorado.edu/en/simulations/gravity-and-orbits/ #Astronomy #GravitationalForce

Gravity and Orbits

Move the sun, earth, moon and space station to see how it affects their gravitational forces and orbital paths. Visualize the sizes and distances between different heavenly bodies, and turn off gravity to see what would happen without it!

PhET

PhET Sims Jun 12, 2024

How does gravity controls the motion of our solar system?
With Gravity and Orbits, students can explore the relationship between the Sun, Earth, Moon and space station, including orbits and positions.
https://phet.colorado.edu/en/simulations/gravity-and-orbits
#GravitationalForce #CircularMotion #Astronomy

Gravity and Orbits

PhET

Corrado May 2, 2024

#Gravity is part of our everyday life. Still, the #gravitationalforce remains mysterious: to this day we do not understand whether its ultimate nature is #geometrical, as #Einstein envisaged, or governed by the laws of #quantummechanics.

https://phys.org/news/2024-05-reveals-quantumness-gravity.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter

New work reveals the 'quantumness' of gravity

Gravity is part of our everyday life. Still, the gravitational force remains mysterious: to this day we do not understand whether its ultimate nature is geometrical, as Einstein envisaged, or governed by the laws of quantum mechanics.

Phys.org

Norobiik @[email protected]Mar 12, 2024

One consequence of the new approach is that at the human scale, #gravity is entirely #Newtonian. But another is that at galactic scales, the acceleration due to gravity can vary by a small but random amount, as if #spacetime were eliciting some kind of #BrownianMotion on the masses within it - generating the extra #GravitationalForce that holds galaxies together.

Spacetime's "Brownian Motion" Could Spell The Death of #DarkMatter
https://www.discovermagazine.com/the-sciences/spacetimes-brownian-motion-could-spell-the-death-of-dark-matter

MSN link: https://www.msn.com/en-us/news/technology/spacetime-s-brownian-motion-could-spell-the-death-of-dark-matter/ar-BB1jIxWG?ocid=emmx-mmx-feeds&PC=EMMX01