Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The expansion of gravity

  1. Aug 22, 2004 #1
    I'm aware that all matter generates their own Gravity, and thus everything is held together, for the Gravity part anyway. However, my question is: Is Gravity all existant, or does it expand/collapse at a rate?

    To clairify my question a bit, I'll ask this. If we were 2 apples in space at quite a large distance apart, and we were to create a planet inbetween them, that had the gravity to pull the apples in, within a short time frame.
    Now, is the Gravity instantly existant at the apples, when the planet is created, or does it take time for the Gravity to reach the apples?

    Similarly, if we were to nullify the planet, would the gravity instantly dissapear, or would it gradually nullify?

    Thanks =)
  2. jcsd
  3. Aug 22, 2004 #2
    Gravity, as proposed by Einstein, travels at the speed of light. Put a planet in betweent he apples, and the gravity will travel in ripples until reaching it's destination. If you remove the planet, I must ask the question, "Are the apples on the planet?" If so, then the affects of removing the planet will be immideately. Otherwise, it will take time to notice the change.
  4. Aug 22, 2004 #3
    Ah, thank you :)
  5. Aug 22, 2004 #4
    No problem, dude.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook