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Limits on size (macro scale)

  1. Oct 21, 2013 #1
    Hopefully this is in the right sub-forum. Anyway, we all know the Planck length placed a limit on how small something can be and still make physical sense. Is there a macro version of this? Is it possible that the universe/multiverse, or some other macro object, can only be so big before it fails to make physical sense?
     
  2. jcsd
  3. Oct 21, 2013 #2

    phinds

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    One of the main contenders for the size of the universe is that it it infinite and I don't think any of the credible arguments against it are that that doesn't make sense.
     
  4. Oct 21, 2013 #3
    If two points are far enough apart that they are both causally disconnected from a 3'rd point half way between them, then I can't think of any sense in which they could be part of the same object.
     
  5. Oct 21, 2013 #4
    Be careful. The plank length is to certain extant a bit arbitrary and we don't really know what happens at that length. It is possible that even smaller scales make sense but have to be dealt with by some physical theories we haven't developed yet.
     
  6. Oct 21, 2013 #5
    My vote's on no since that suggests at larger sizes we have a set definition for what an "object" is
     
  7. Oct 21, 2013 #6
    Infinities supposedly don't occur in nature, though, if I'm not mistaken, though they may occur in black holes. Is it possible a macro sized object could only be so big due to the energy in that space being finite?
     
  8. Oct 22, 2013 #7
    well infinities indeed tend not to exist , and the places where we think they are are rather because either we have a lack of knowledge about them as of yet or because or theories are not perfect enough to give a more precise understanding or maybe mother nature just doesn't let you see in what happens at the center of a BH for example.
    But I doubt one can call the center of a BH a true infinity in the classical sense , as that center still formed from a star that had some finite amount of mass and even after all that matter that has fallen in still has some finite mass not infinite.

    Also I think there are constraints as to how large an object can get and they have to do with the density of that particular object , as when the mass would be large enough and the density too which are actually kinda related then that object would start to form a Black hole.After that I think you have to look upon how big a BH can get.
     
  9. Oct 22, 2013 #8

    jtbell

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