1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gravitational Paradox

  1. Sep 1, 2015 #1
    Galaxies outside the observable universe are moving away from the Earth faster than the speed of light. As the two bodies move apart, the gravitational force between them should weaken however as the speed of gravity is equal to the speed of light, the gravitational force would not do so. It is now that a paradox arises, for if the gravitational force between the two bodies is unable to weaken, then Newton's law of universal gravitation is compromised. The issue can be solved if the change in the force of gravity between two bodies occurs not at the speed of light but is instead instantaneous. This, however, would compromise Einstein's general theory of relativity. How can this paradox be solved or simply dismissed?
  2. jcsd
  3. Sep 1, 2015 #2


    Staff: Mentor

    Newton's law of Gravitation is compromised. It simply doesn't work at cosmological scales.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook