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Worm and black holes

  1. Nov 22, 2007 #1
    a black hole is basicaly a massice rip in space with an invisible gravity source.
    a wormhhole is a rip in time and space.

    so if a black hole ran into a worm hole or a pair of each then what would happen,:confused:
     
  2. jcsd
  3. Nov 22, 2007 #2
    Assuming wormholes can exist...

    If the black hole was comparatively small, it could just pass through.

    Otherwise.. you'd expect to end up with two black holes. Quite odd..
     
  4. Nov 22, 2007 #3

    PhY

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    You must find the cause of these holes.
    Black holes are caused by the death of a planet imploding I think.
    Black holes have magnetism, do worm holes have magnetism?
    Then again do they move and go into an orbit like a satellite or do they just run through like a comet?
    Worm holes have forces of attraction?
    such that M>m ? and a worm hole is attracted to a black hole?

    Wait ... I don't know what i'm talking about...but hope these questions I've asked helped.
     
  5. Nov 22, 2007 #4

    Chris Hillman

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    Wormhole?

    I wouldn't put it like that. See Geroch, General Relativity from A to B for an accurate geometrical picture.

    There are many things one could mean by a wormhole, and for the ones I know about, again, I wouldn't put it like that. But the most important thing you need to recognize is that astronomers have by a combination of strong theory and strong observations accumulated a wealth of evidence that black holes exist in nature, and also have a good idea how they would form and a good idea of many of their properties. The notion of a "traversable wormhole" (the notion you most likely have in mind) is in contrast a theoretical speculation which has been severely criticized on theoretical grounds and for which there is at present absolutely no observational or experimental evidence (that I am aware of).

    Well, first, can you clarify what you mean by a wormhole and what your math/sci background is? It sounds like you read something on some website or in some popular magazine, so the best procedure might be for you to simply quote in full the paragraph (?) you read which mentions wormholes. Or tell us the title and date of the mag, or give a link to the website.

    That doesn't sound correct under any circumstances, at least not in classical gtr. If you really believe this, can you write down a model of a traverseable wormhole and show me some mathematical argument for how you think this might work, according to gtr?

    No. There are plenty of popular books which discuss how astrophysicists believe black holes can form in nature; try Kip. S. Thorne, Black Holes and Time Warps, Norton, 1994.

    Actually, in these models, the ionized matter outside the black hole itself supports a magnetic field.

    [EDIT: PhY, I didn't see the word " these questions I've asked", so I misunderstood the tenor of your post. I deleted my previous comments. There is a PF feature whereby you have something like 24 hours to choose to delete your own post, and I hope you will do that with your Post #5. Then we can start afresh with, I hope, no hard feelings. TIA, and thanks for your positive comments.]
     
    Last edited: Nov 22, 2007
  6. Nov 22, 2007 #5

    PhY

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    I really enjoyed reading your well explained post, and I learnt something new,

    Unnecessary editorial comments removed

    Integral

    [
     
    Last edited by a moderator: Nov 22, 2007
  7. Nov 22, 2007 #6
    Cosmic censorship.
     
  8. Nov 22, 2007 #7

    Chris Hillman

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    Either I misunderstood what you were trying to tell the OP, or else you'll need to explain more fully.
     
  9. Nov 22, 2007 #8
    Firstly, what evidence I know of suggests that wormhole topologies probably aren't physical. Frequently the metrics require material that is "exotic" (ie. probably doesn't exist), and even the block-universe philosophy requires something almost as abhorrent as super-determinism to deal with the potential CTCs. Having pointed this out, what follows is necessarily speculative.

    I assume you agree that if a black-hole was small compared to a wormhole, it could pass through it just like any other particle. All that remains is to consider the opposite limit in which the black-hole is large compared to the wormhole (since the intermediate case would obviously demand a more quantitative approach):

    Note that it is the mouth of the wormhole which I am considering to be small compared to the black hole, and that I am presuming that the other end ("tail"?) is well separated (say, in a different galaxy, noting that typical wormhole solutions treat the ends as effectively in different "universes"). By a similar argument as before, the mouth of the wormhole should be free to pass beyond the black hole event horizon.

    This means that in the other galaxy, the "tail" of the wormhole now connects to the interior of a black hole. By the (weak) cosmic censorship conjecture, there must necessarily be another event horizon, say across the "throat" of the wormhole, to prevent information from the singularity escaping to this second galaxy. Hence, the tail of the wormhole behaves as a second black hole (accepting radiation but emitting nothing).

    Admittedly, this all rests on the WCCC, which is on no firmer foundation than the non-existance of wormholes (particularly noting this month's surprising Physical Review Letter regarding the ability of quantum processes to spin the event horizon off of a large classical near-critical black hole, assuming we believe in the likes of Hawking radiation). But what reasonable alternative possibility is there in this limit? (E.g., wouldn't expect the wormhole connection to suddenly sever off, since there is nothing locally special about the event horizon.)
     
    Last edited: Nov 22, 2007
  10. Nov 22, 2007 #9

    Chris Hillman

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    Agreed, and I assume we are talking here only about the hypothetical (and highly dubious!) notion of "traverseable wormholes", treated according to gtr (and assuming exotic matter with appropriate physical properties, such as not resisting the passage of ordinary matter).

    I don't see why not, assuming we can neglect possible "exotic matter drag".

    So we are agreeing not to try to draw any conclusions about that case at all? Fair enough.

    Something like different exterior regions in a Carter-Penrose diagram for an AF spacetime? I quibble, but never mind that. OK, so you are basically thinking of a long thin handle with one end approaching a Flamm paraboloid thingie with a throat much larger than the wormhole throats (I misunderstood this previously).

    Well, its handwaving, even assuming CC, but at least I think I understand now what you had in mind... Thanks for clarifying!
     
  11. Nov 25, 2007 #10
    black holes are cused by a star imploding
     
  12. Nov 26, 2007 #11

    Chris Hillman

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    Better say something like this: "Astronomers believe that under some circumstances, a (solar mass) black hole is formed when the core of an exploding supernova undergoes complete gravitational collapse". (The outer layers of the star are blown off in the explosion and form a visible remnant made of ordinary matter.)
     
    Last edited: Nov 26, 2007
  13. Nov 27, 2007 #12
    yeah, wormholes mean many things and aren't exactly fully understood *as are black holes). But we think that aa worm allows people to travel, and may also be a rip in space time. If you think that a ormhole is the same as a black hole, then they would collide to f orma larger blackhole. However if the ormhole is not a black hole, and as i earlier suggested a form of travel, then it may just pass through it as i think somebody said a while ago. But you should do some research about"tearing" space-time.
     
  14. Nov 27, 2007 #13

    Chris Hillman

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    athrax, I can't understand what rubecuber was trying to tell you, but to repeat:

    The notion of a traversable wormhole is a theoretical speculation so far unsupported by experimental evidence. It seems that to make one you need so-called "exotic matter", which would have properties much stranger than anything humans have ever succeeded in making, and there are many reasons to doubt that such stuff can exist. Even worse, it appears that traverseable wormholes would require large amounts of this alleged stuff, which seems to involve infeasible transport of large amounts of mass-energy. Even worse than that, there is little theoretical justification for positing the existence of stuff with the properties of "exotic matter"; basically the only reason is that stuff with these properties would be required to hold open the alleged wormhole!

    All in all, at present the notion of a traverseable wormhole appears theoretically dubious and utterly unsupported by experimental evidence. In contrast, the notion of a black hole is theoretically well understood and well motivated in theoretical astrophysics, and in addition is solidly supported by a wealth of observational evidence.

    There are some slight caveats about the implausibility of exotic matter (effective field theory approximations of certain QFT effects do bear some resemblance, but when you look deeper the implausibility is apparent), but I think discussing these would only distract from the main point.
     
  15. Dec 3, 2007 #14
    you know what chris just because you don't understand doesn'tmean other's can't, so just think about other's feelings next time! << edited by berkeman >>
     
    Last edited by a moderator: Dec 3, 2007
  16. Aug 27, 2008 #15
    please exuse me for the missinformation. i now understand what a black hole is but has a wormhole go substance?
     
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