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Does the universe specify a mass limit?

  1. Aug 11, 2003 #1
    [SOLVED] Does the universe specify a mass limit?

    This may be mad or it could be dumb. But the thought occured and I don't have the tools at my disposal to know. I hope someone could tell me (politely if possible, but I'm not overly sensitive) if the proposition in the attachment makes any sense at all?


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  2. jcsd
  3. Aug 11, 2003 #2


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    I must not know how to open attachments---dont see where
    to click in this case.

    Could you just say roughly what the idea is about

    I think there probably is some implied limit on
    energy DENSITY---that is how much mass or energy you can have
    concentrated per unit volume

    maybe there is no limit on how much mass there can be (I dont know about that) but there probably is a limit on how much
    mass can be concentrated in a small place----some kind of upper limit on density

    but what is your idea?
    and could you say it in a post instead of making us look in an attachment?
  4. Aug 12, 2003 #3
    Pesky attachments

    Sorry about the attachment problem. I couldn't see any attachment either once I'd posted it. I assumed it was being moderated before appearing. Still here we go with the idea.

    I have a problem with infinite answers and this thought occured, but I don't have the background to know if it is ridiculous or not.

    Bekenstein/Hawking entropy implies that if the energy emitted by a black hole is greater than the energy absorbed by a black hole then at a point in the future a black hole could conceivably evaporate.

    However, if the energy absorbed is greater than that released by the Bekenstein/Hawking entropy then at a point the mass of a black hole becomes infinite.

    If an object has an infinite density then wouldn't the curvature of space/time would be warped by the gravitational force to an infinite degree.

    This would appear to be an unacceptable state for a stable universe. Infinite mass producing an infinite gravitational force.

    Given the number of stars that have been born, exhausted their fuel and died during the lifetime of our universe. A proportion of which would have exceeded the Chandrasekhar Limit and formed a black hole upon collapse. Our universe should be a raging storm of competing consuming infinite gravitational forces. Stability should be impossible.

    The existence of a singularity assumes that the curvature of space/time can be warped to an infinite degree.

    If c is the speed limit imposed on all matter/energy in our universe it would seem that a mass limit is not beyond the boundaries of the possible.

    If such a limit on the curvature of space/time existed then the paradox of a singularity should never occur.

    As the mass of a black hole increases the corresponding warping of space/time increases but would never manage to reach an infinite point of mass.

    By exceeding a speculative mass limit the fabric of space/time would no longer be able to support mass of the black hole. The energy accumulated from the vast compressed matter of the black hole could be dumped into a space (universe?) that previously had not existed.

    Andrew Strominger has shown that a tear in a Calabi-Yau shape could, or would be sealed without catastrophic effects on the surrounding space. Presuming that our universe agrees with his maths, an excessively massive black hole could literally disappear from our universe.

    Taking this one step further, disappear from our universe and appear in a universe of it’s own making.

    A supremely dense amount of energy appearing in a space that previously did not exist sounds suspiciously like a big bang.

    A further consequence of this proposition would be the removal of the gravitational effect of the black hole on our universe.

    Without needing an artificially constructed Cosmological Constant or a speculative negative energy of empty space under tension, a counter force to an always-attractive gravitational force could be described. Gravity, under the most extreme of circumstances could be self-eliminating.

    I'm pretty much expecting there to be a simple reason why this is not the case, but it seems answer questions I've read raised about the initial state of our universe.

    Be gentle with me please.
  5. Aug 15, 2003 #4
    My guess would be that the present universe cannot exist in its present state with an infinite mass for a very simple reason - if it had infinite mass, it would collapse back to a point due to gravitation. For a stable universe (I think ours might be like that) the expansion of the universe should more or less counteract the gravity.

    I think that for a universe with infinite mass to not collapse to singularity it should be expanding at infinite speed...

    Oh well, probably I've messed everything up anyway... :wink:
  6. Aug 15, 2003 #5
    Or... there could be negative mass with negative gravity? Just guessing...
  7. Aug 17, 2003 #6
    well, as you said, a black hole will evaporate in a finite time by hawking radiation if the hawking radiation is greater than the infalling matter. If the reverse is true, it depends on the amount of matter available for the hole to absorb (depends on radius of visible universe from P.O.V. of bh). Most of the matter in the universe will be in the form of evaporating black holes.
    what you're talking about sounds similar to the "big-rip." (So what happens when the event horizon of a black hole meets the hubble radius?)
  8. Aug 21, 2003 #7
    Swartz - Looking at the universe as a whole - one can use the black-hole event horizon formula to conclude we are living in a black hole - so the event horizon of the universe is always equal to the Hubble radius. Moreover, if you apply the null universe assumption - the energy contained in the expanding Hubble sphere will always have critical density - in other words - as the absolute magnitude of negative potential energy decreases the totality of the stress energy contained in the vacuum must increase - its always a perfect balance.
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