4 ms·

Since gravitational waves travel at the speed of light there should be a delay as well where the gravity of one body is affecting another from where it was not

• rocqua 7y ago
  I recall hearing that another effect in GR compensates for the delay of gravitational waves to make a binary system act according to newton's laws.
• gbear605 7y ago
  In fact, this is not how it works. My understanding is that whatever the gravitational force is carried by (ie. gravitational waves) is also affected by the velocity and rotational velocity of the gravitating object (in this case, the Sun), so the Earth really is attracted to the Sun’s current position, not where it was 8 minutes ago. Of course, this only works if no net forces are applied to the sun in those eight minutes, but that’s almost definitely the case. I believe, although it’s been a while since I did the calculations, that if this were the case then the galaxy would gradually become funnel shaped before eventually dissipating after the center gets too far away from the rest. It would have similar effects on the solar system as well.
  • Simon_says 7y ago
    > current position Careful there, buddy.
    • gbear605 7y ago
      Okay, yes, current position is not quite correct, but you can replace each instance of it with “the position of the Sun after the same amount of time as it takes for light to get to the Earth from the Sun, according to an observer that is stationary and on neither,” but that’s a mite clumsy (and still not totally correct, but good enough)
      • Simon_says 7y ago
        What does “stationary” mean?
        • gbear605 7y ago
          Poor wording there as well :) Perhaps “not experiencing net force“
          • Simon_says 7y ago
            You have reinvented inertial reference frame, but that doesn’t give you what you want either.