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Thread: BLACK HOLES:HOW DO THEY SUCK THINGS IN AND CRUSH THEM?

  1. #1 BLACK HOLES:HOW DO THEY SUCK THINGS IN AND CRUSH THEM? 
    Forum Freshman ADAMA's Avatar
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    I THINK THAT THERE IS SO MUCH DENCETY THAT THE MATTER JUST GETS CRUSHED.


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  3. #2  
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    IS THIS A DISCUSSION, OR DID YOU JUST WANT TO STATE THAT? I MEAN NO OFFENSE IF:

    A) THE CAPS LOCK IS ACIDENTAL
    B) YOU WERE ACTUALLY INTENDING TO DISCUSS THIS RATHER THAN JUST SPAM WHICH IT LOOKS A BIT LIKE YOU ARE

    ANYWAY, YES, THE BASIC PRINCIPLE OF A BLACK HOLE WOULD BE THAT MATTER ENTERS DUE TO GRAVITATIONAL FORCES, AND IS BROKEN DOWN INTO CONSTITUENT PARTICLES, PACKED CLOSELY TOGETHER, TO RESULT IN THE HIGH DENSITY.

    The capitals are annoying, no?


    "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." ~ Douglas Adams
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  4. #3  
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    Is there actual evdence of the existance of black holes or is it still a theory?
    if so where is one.
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  5. #4  
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    Quote Originally Posted by fizzlooney
    Is there actual evdence of the existance of black holes or is it still a theory?
    if so where is one.
    You can not see blackholes through light, because their horizon emits the light itself. But you can calculate the gravitational repsonses. There is a considerable debate going on that the centre of galaxies have (actually "are") super massive black holes. That's why we end up galaxy pictures when we search "black holes" on internet. Even Nasa has a catalogue of galaxy merging pictures as examples (aka evidences) of black hole activities. What you see as a galaxy is actually matter collapsing into black hole's gravitational horizon, but it takes time, sometimes billions of years in process.
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  6. #5  
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    Quote Originally Posted by fizzlooney
    Is there actual evdence of the existance of black holes or is it still a theory?
    if so where is one.
    Along with a black hole there is predicted to be energy emitted by the matter that is in close orbit around the hole. A hole does not "suck" anything. It simply has a gravitational effect, and outside of the event horizon that effect is quite ordinary -- it simply that same gravity that you would expect from a body of the same mass as the black hole at the same distance from the center of it. It is only near the event horizon and beyond it, where space-time curvature is extreme that things get weird.

    The energy that is released by the material orbiting it is detectable. So is the gravitational field as reflected in the orbits of objects around the black hole. Based on those sorts of observations it is believed that astronomers can "see" black holes in other galaxies -- that is detect some of the energy emitted and see groups of objects orbiting something that is consistent with a black hole. That same sort of observation and reasoning has led to the widely-held belief that a massive black hole exists in the center of the Milky Way galaxy as well as many other galaxies.

    Observation is pretty subtle. But you can find articles with an internet search. Here is one. http://www.sciencedaily.com/releases...0111182222.htm
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    Have they detected gravitation waves. Like the LIGO experiment?
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    It's rare to hear of blackholes spoken of in other than defacto language.

    Is there is any observational evidence that would distinguish a black hole from an object that is collapsing according to external clocks?
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  9. #8  
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    Black holes have also been observed while "feeding" on matter. While "feeding" they are shooting out jets of matter showing that some very powerful force is at work where matter goes in, is changed substantially, and some of it is shot back out. Do a search for "black hole jets" you should find something.
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  10. #9  
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    Quote Originally Posted by marcusclayman
    Black holes have also been observed while "feeding" on matter. While "feeding" they are shooting out jets of matter showing that some very powerful force is at work where matter goes in, is changed substantially, and some of it is shot back out. Do a search for "black hole jets" you should find something.
    Thanks. I was actually looking for evidence of another sort.

    Rather than the claim
    "black holes can have jets,"
    something like
    "pre black holes cannot have jets,"
    or
    "pre black holes can have jets too."
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  11. #10  
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    pre-black holes, typically, aren't 'dense' enough to make a jet, it takes densities on the order of the event horizon to accomplish the feat
    Wise men speak because they have something to say; Fools, because they have to say something.
    -Plato

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    I haven't gone to re-find the info in Hawking, but I recall something about the point singularity not actually being a point - instead just an extremely dense physical object. A circuit engineer friend of mine disagreed with me.

    Anyone know it off the top of their heads? I'm lazy about looking stuff up I had once read. Would the neutron-core material that would make up a black hole be called "Neutronium"?
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  13. #12  
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    Quote Originally Posted by C_Sensei
    I haven't gone to re-find the info in Hawking, but I recall something about the point singularity not actually being a point - instead just an extremely dense physical object. A circuit engineer friend of mine disagreed with me.

    Anyone know it off the top of their heads? I'm lazy about looking stuff up I had once read. Would the neutron-core material that would make up a black hole be called "Neutronium"?
    The singularity predicted that is associated with a black hole is not a point.

    If you use Einstein-Cartain theory instead of GR then I am led to believe that you don't have a singularity at all.
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    Quote Originally Posted by Arcane_Mathematician
    pre-black holes, typically, aren't 'dense' enough to make a jet, it takes densities on the order of the event horizon to accomplish the feat
    Maybe I should look into jets. From what you say, pre-black holes seem to fit the bill nicely.
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    Quote Originally Posted by Arcane_Mathematician
    pre-black holes, typically, aren't 'dense' enough to make a jet, it takes densities on the order of the event horizon to accomplish the feat
    Maybe I should look into jets. From what you say, pre-black holes seem to fit the bill nicely.

    But maybe my objections are moot. Is there a metric describing spherically collapsing matter?
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  16. #15  
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    If you use Einstein-Cartain theory instead of GR then I am led to believe that you don't have a singularity at all.
    Are you talking about a 2D disc or something else?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    a 2D disc still goes back to the question: can you have a physical object that eliminates one dimension or more?
    If it's a "point" singularity, with no actual dimensions, or at least retreating from them to the point of infinity, or a 'perfectly' flat disk along the equator...does it make a difference?

    There might be some difference in the attraction at the poles? If Earth varies it's gravity locally due to a mountain or concentrated metallic deposits in one area, it seems reasonable that a 2D disk would have "local" variations in its extreme gravitational 'map' depending on the distance out from the axis of rotation? (looking straight down the pole, at the 33 1/3 record lying flat)...(how many people in here have no clue what I'm talking about vs how many who understand it immediately?)
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    A 2D disc is what is actually predicted to occur with any rotating singularity (which would be all of them, since angular momentum is conserved). I was just wondering if it is predicted by conventional GR or by Einstein-Cartan theory.

    I would imagine that the exact shape of the disc might be a bit contorted by other masses that have not yet fallen all the way into the singularity and also that the singularity itself would probably orbit a centre of mass, which would produce an area where matter could be actively eaten as the event horizon moves in and out.
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    Well that 2D disc might also have anomalies as the mass of infalling matter joins it in different locations, mightn't it?
    Or is any variation so small compared to the terrific gravity overall that the ripples are totally lost among the tsunami?


    Has anyone postulated theories on this?
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  20. #19  
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    Quote Originally Posted by C_Sensei
    Well that 2D disc might also have anomalies as the mass of infalling matter joins it in different locations, mightn't it?
    Or is any variation so small compared to the terrific gravity overall that the ripples are totally lost among the tsunami?


    Has anyone postulated theories on this?
    Not sure what the math says, but I'd imagine that the moment the matter is infinitely compressed when it joins the singularity it pretty much is indistinguishable from it, i.e. totally merges with it. For variations to be present within the disc itself would require density variations which would be impossible in an already infinitely compressed object. At least, this is how I think about it, but would very much like the opinion of someone way more into the know (hint: Dr R).
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    It begs the questions:

    How fast does it merge with the disc into "infinite" compression?

    Is the compression actually "infinite" or merely approaching that?

    At what point during the infall are electrons stripped form their orbits, and at what point crushed into the protons?

    Is the disc made of the same material we find in the core of a Neutron star/pulsar, or is it likely that Neutrons themselves are even broken down further?
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  22. #21  
    Forum Professor marcusclayman's Avatar
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    "How fast does it merge with the disc into "infinite" compression? "
    I'm sure my answer will deceive my ignorance, but my blind guess would be: infinitely fast, once it reaches close enough to interact with the singularity.
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    But when 'gravity' i.e. curvature goes to infinity, doesn't time also go to infinity?

    The thing about these equations is that they might not describe what actually happens inside the hidden singularity, point, disk, or 3D core.

    Perhaps the religious twits we shoot into the black hole will take an infinite amount of time to reach the singularity from their frame of reference, but for us, on the outside, they would hit it at the normal rate we would expect for any object falling down any stellar-scale gravity well?
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  24. #23  
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    Quote Originally Posted by C_Sensei
    But when 'gravity' i.e. curvature goes to infinity, doesn't time also go to infinity?

    The thing about these equations is that they might not describe what actually happens inside the hidden singularity, point, disk, or 3D core.

    Perhaps the religious twits we shoot into the black hole will take an infinite amount of time to reach the singularity from their frame of reference, but for us, on the outside, they would hit it at the normal rate we would expect for any object falling down any stellar-scale gravity well?

    What is going on is that the solutions to the Einstein field equations result in a curvature tensor that has infinite components on some hypersurface. That hypersurface is a singularity, which simply means that the equations become undefined and the theory has broken down.

    It does make sense to say that "time goes to infinity".

    Someone crossing the event horizon, would, in his reference frame, hit the singularity in a finite time. To someone outside the event horizon, they would seem to hang just outside the event horizon indefinitely. That is a result of the extreme curvature of space-time.

    The singularity itself gets a lot of play in the popular press. But don't take it too seriously. Most physicists would tell you that the singularity is probably just an indication that general relativity has broken down and other phenomena come into play -- quantum mechanics for instance. It is known that general relativity and quantum mechanics are incompatible. Perhaps a theory capable of addressing both quantum effects and gravitation will provide a better explanation. Or perhaps the problem lies elsewhere.

    There is an alternate theory to general relativity, called Einstein-Cartan theory. EC theory gives predictions that are sufficiently close to GR in most situations that it is not possible to distinguish between EC and GR with current measurement technology. But EC does not predict a singularity for black holes or for the big bang.

    Bottom line: The thing that is important with regard to a black hole is the event horizon, not the singularity.
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    I would disagree - I would say the event horizon is simply a boundary you pass, that is nothing more than like a guarded border: it can be passed easily (one way!), but you sure know it's there, and the game changes entirely when you do pass it.

    It's the singularity I am extremely interested in. Since GR breaks down near it, could we not hypothesize that the singularity therefore leaves our universe?
    Or does a proven takeover of Quantum Mechs disprove this?

    Don't physicists really really want to know what happens at the singularity?
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  26. #25  
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    I think what DrR is saying is that what makes a black hole a black hole is the event horizon, not the possible existence of a singularity.
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  27. #26  
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    Quote Originally Posted by salsaonline
    I think what DrR is saying is that what makes a black hole a black hole is the event horizon, not the possible existence of a singularity.
    Precisely.
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    Agreed.

    But do we have much proof or precedent to suspect a naked singularity?
    I don't see how it can exist; by definition at a certain radius, light cannot escape and thus we will see the event horizon.

    In either case, isn't the singularity what we have to investigate? How can we? With Tachyons?
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  29. #28  
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    Quote Originally Posted by C_Sensei

    In either case, isn't the singularity what we have to investigate?
    No.
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    Do you think it's entirely un-investigable? Ineffible? Why can't we eff it?
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  31. #30  
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    Quote Originally Posted by C_Sensei
    Do you think it's entirely un-investigable? Ineffible? Why can't we eff it?
    First, a singularity is not a thing. It is the lack of mathematical consistency at a location modeled in space-time.

    Second, if there is something odd at the predicted location, it is inside the event horizon of a black hole. That makes it causally removed from our little corner of the universe. We simply cannot get any signal from that place.

    Third, there is no particular reason to believe that the singularity is real. Most physicists interpret the singularity as simply an indication that general relativity has broken down and that it will probably take a theory that can simultaneously handle quantum phenomena and gravity to explain what is happening. An alternate perspective is offered by the fact that if one uses Einstein-Cartan theory rather than general relativity to model gravitation, then there is no singularity.

    If you can find a taxi cab that will take you to the event horizon of a black hole (there is probably one at the center of our galaxy) then go right on in. You will hit the singularity pretty quickly if it exists. You might be in a somewhat different state from "as issued" when that happens. But you can eff to your heart's content.

    You may find it difficult to publish the results of your exploration.
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  32. #31  
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    What does Einstein-Cartan theory predict if not a singularity? A small, closed universe type deal?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    If tachyons DO travel faster than light, why can we not use them to explore the singularity inside the event horizon?

    Are you entirely sure that
    a singularity is not a thing
    ?

    Why can it not be simply a larger pulsar; a larger core made of neutronium?
    Only one so massive that c is insufficient to escape its gravity well.

    Does the math show it must be a flat disk/dimensionless point?
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  34. #33  
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    Well, if it were anything other than a dimensionless point, it wouldn't be a singularity. In reality, it probably isn't a dimensionless point. We still call it a singularity because our current best understanding of the way things work says that it should be one, but it also says there are some infinities involved, which doesn't make physical sense, so all that means is that our current best understanding is probably not perfect under such extreme conditions.
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    Quote Originally Posted by C_Sensei
    If tachyons DO travel faster than light, why can we not use them to explore the singularity inside the event horizon?...
    Tachyons are impossible.
    The cause:
    Coordinate velocity of light is 299792458 m/s.
    Proper velocity of light is infinity.
    By the way: speedometer of your car measures the proper velocity, and, as a result, the upper limit of the proper velocity of the ideal car is infinity, as a result, tachyons must move with proper velocity, which is more then infinity. Is it possible?

    PS:
    Black holes are objects, whose gravity field energy, outside of Schwarzschild radius, is equal to the rest energy, mc^2, the energy of mass m, concentrated on the Schwarzschild sphere.
    Magnetic holes are objects, whose magnetic field energy, outside of critical magnetic radius is equal to the rest energy, mc^2, of mass m, concentrated inside the critical magnetic radius.
    Magnetic holes were invented by alternative-physicists, as a result, this theory will not be accepted by orthodox-physicists, as a result, microscopic magnetic holes will be created soon (may be in November 2009)… Fasten your belts…
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