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Does gravity affect gravity the way gravity affects time?

  1. Apr 18, 2009 #1
    Since time is part of the equation for acceleration, and time slows as gravity increases, would this not limit the amount of gravity a black hole could produce? It seems that this would be a kind of negative feedback that would prevent the formation of a black hole out of an accretion disk.

    What am I missing?

    Now, if this were so, we would observe that the outer reaches of galaxies are more effective in producing gravity than the inner reaches of galaxies where the gravitational field is strongest. Such a condition would skew our calculations about the orbital speed of stars as they move in galactic orbit. Stars with extra massive black holes would show the effect more than less massive galaxies.
    Last edited: Apr 18, 2009
  2. jcsd
  3. Apr 18, 2009 #2
    I am not sure I understand your question. You should probably reword it. I will do my best to answer it though.

    Time is relative that means that relative to the black hole it is experiencing time normally it is only for the outside observers that time seems to have slowed down.
  4. Apr 18, 2009 #3
    I also do not understand your question. Could you please reword it or explain what you're trying to ask, so we can help you? Are you trying to say that because time seems to slow down for the black hole from an outside observer's point of view that this in turn limits the black hole's gravity because the acceleration is limited?
  5. Apr 18, 2009 #4
    An object in a gravity field experiences time more slowly. I was wondering what effect this would have on the ability of a black hole to form. It seems that the slowing of time would also reduce the force of gravity because time is part of the equation for acceleration. I know this may only be noticed by an observer outside the field, but wouldn't the reduction in gravity due to gravity act as negative feedback. Would this prevent a black hole from forming?
  6. Apr 18, 2009 #5
    But wouldn't an inside observer see the time of an outside observer speeding up relative to his own? This is different from relative speed where each observer sees the others time as slowed.
  7. Apr 18, 2009 #6
    Yes an observer in the balck hole would see outside events happen faster.
  8. Apr 18, 2009 #7


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    This has been discussed in the Relativity subforum several times. Try a search.

    For a very distant observer nothing really passes the event horizon in finite time, but it still disappears due to infinite time dilation resulting in infinite red-shift. So the black hole grows.
  9. Apr 18, 2009 #8
    Could you explain how you came to this conclusion?
  10. Apr 18, 2009 #9
    So a black hole could never actually form because the material collapsing into it would take forever to get there?

    (EDIT I had typed something about time slowing down here, but I regret typing it because I'm not clearly expressing myself EDIT)

    Nevertheless, there is a competitor to the idea that black holes are real, called "Eternally Collapsing Objects" (ECOs). Many astronomers consider the ECO theory to be wrong, but in science it's interesting to ask provocative questions.
  11. Apr 19, 2009 #10
    Yes; I have Googled and searched, the puzzle I am left with is that it seems that gravitational force should affect the amount of gravitational force an object can produce. I view the fact that time is part of the equation for gravitational acceleration as a clue that this may be so. Then I think that if this is so, might this not be the cause of the anomaly seen in galaxy orbital rates?
  12. Apr 19, 2009 #11
    Time is part of the equation for gravitational acceleration. Gravitational acceleration determines the rate at which galactic stellar objects rotate. It seems that calculations about the rotation rate of these stellar objects should need adjustment to account for time dilation as a result of the increased gravity toward galactic centres.

    I'm not sure whether the calculations that show galactic rotational anomalies account for this or not.

    I mentioned black holes because the thought came to me while I was considering a possible limiting factor that would prevent the singularity from forming at the centre of a black hole.
    Last edited: Apr 19, 2009
  13. Jan 9, 2011 #12
    Can someone provide the link to the answer to this question. I've had no luck finding the answer in the relativity forum.
  14. Jan 21, 2011 #13
    As far as a link for this? A Simple Google search should provide some information on this for you, But if youre looking for an answer specifically relating to his question on the ability of black holes to form relative to time, the answer lies in the thread.

    Time is relative to the situation. Gravity in large amounts will slow time relative to the source of the gravity, aka the black hole, while outside it would seem to have slowed down near the black hole. Time is going at normal speed for the black hole essentially, but outside observers see it as being slowed. If you fell into the black hole, time wouldnt slow down for you, but you would essentially see everything outside the black hole speed up.

    Everything is relative to the frame of reference.

    Hope this Helps,
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