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When Black Holes Collide 127

Posted by samzenpus from the double-event-horizon dept.
EricTheGreen writes "CNN.com reports on a pair of black holes in a mating dance that can only end badly for both of them. Fortunately they've still got several million years for the emotional rush to wear off and realize what a terrible mistake they're both making..."
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When Black Holes Collide More

When Black Holes Collide

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  • Why? (Score:2, Funny)

    by JordanL ( 886154 )
    Why did this remind me of that Family Guy episode?

    "President Douchebag: I just got a call from my challenger.
    Crowd: Boooo!
    President Douchebag: Now now, Mr. Daterape ran a fine campaign."

  • yup... (Score:2, Funny)

    by 3.14159265 ( 644043 )
    gravity sucks...

  • Oh boy (Score:2, Funny)

    by Klowner ( 145731 )
    First blue rings around uranus, now we've got black holes colliding.. This place is really getting to disgusting for me.

  • LISA (Score:3, Informative)

    by alta ( 1263 ) on Friday April 07, 2006 @11:32AM (#15085139) Homepage Journal
    Neat, a new telescope thing called LISA will be able to detect the merger. If they can keep the power on for a few million years.

    • Re: (Score:3, Informative)

      by account_deleted ( 4530225 )
      Comment removed based on user account deletion
    • The LISA telescope won't last that much: it'll soon be replaced by the MACINTOSH telescope.
      • Yeah, but then someone will take the MACINTOSH telescope, clone its lens, and release the clones with added security holes.
        • At the same time the origonal team leader of the LISA telescope will be snubbed and storm off to create an overdesigned and exensive telescope called NEXT - which will be coveted by high-end astronomers, but will be panned by everyone else until it's core tech is purchased by members of the MACINTOSH telescope in which case it will usher in the 10th iteration of tech design.

          There! Try to keep this lame thread going NOW.
          • Eventually an astronomy student will create his own lens after being told he can not modify a telescope built by someone else. Then other astronomers will add more parts to this lens, and the LINUX telescope will be completed. These enthusiasts will then proclaim their telescope the best every created, and some will claim that is impervious to space dust that plagues the popular telescopes. This telescope will battle other popular telescopes with its main claim that it makes astronomy cheaper to do.

            Th

            • Naw - you fell off the apple tree. Good try though. If you were to get away from Apple jokes then you'd have to add Atari, Commodore, Sol, the Altair, IBM Microsoft and all the rest.

  • Sooner than you think (Score:5, Interesting)

    by Skevin ( 16048 ) on Friday April 07, 2006 @11:36AM (#15085184) Journal
    > Fortunately they've still got several million years

    Umm, how many light years away is this? Sure, it might take million years for the *light* from the spectacle of them merging to reach us, but if they're millions of light years away (center of the galaxy?), they may have already merged.

    I've always speculated as whether gravity travels like light. Would "gravity waves" from the merge be felt here on earth the instant it happened, or would it take the same amount of time as light/electromagnetic radiation to reach us?

    • No Information can travel at the speed more than that of light.
      Even if (just a hypothesis) gravity waves reaches here at the instant it happened, it means that it is not detectable, since if we can detect it, it means information travelled at more than the speed of light.

      Anyways, einstein proved that the concept of 'same instant (instantaneous)' is not there anymore.
      So that q itslef is not valid.

      • Even if (just a hypothesis) gravity waves reaches here at the instant it happened, it means that it is not detectable, since if we can detect it, it means information travelled at more than the speed of light.

        Alternatively, it could mean that no information can travel at more than the speed of light, except in the form of gravity waves.

        I mean, shouldn't "No Information can travel at the speed more than that of light" really be "There's no known mechanism by which information can travel at a speed more than
      • The way I humbly understood it, gravity is a deformation of space-time, and thus doesn't really travel and is instataneous, or something like that. Anyways, with that quantum thing about two particles changing of state at the same time, isn't it possible to transmit information instantaneously?
        • Two ways to look at it -
          First way -
          Every force is believed to be set up by a particle as per current theories -
          and gravitational force is caused by gravitons. And gravitons can move at the speed of light and no faster.*
          The second way -
          When black holes merge, the merging will cause a different sort of deformation of space-time. Now, for that effect to reach out to some other particle, it has to travel, and that wave travels at the speed of light and no faster*

          Also, for the second point you mentioned, there i

    • Re:Sooner than you think (Score:4, Insightful)

      by BlewScreen ( 159261 ) on Friday April 07, 2006 @11:47AM (#15085316)
      I've always speculated as whether gravity travels like light. Would "gravity waves" from the merge be felt here on earth the instant it happened, or would it take the same amount of time as light/electromagnetic radiation to reach us?

      If you take a look at this book [amazon.com], you'll find that there is a way to measure the "speed of gravity" (according to the author) and that it is indeed faster than the (current) speed of light.

      I'm not going to agree or disagree with what he puts forth, but if you're interested in questions such as the one you propose above, you'll probably find the book interesting. The supposition is that the speed of light and the speed of gravity were, at the time of the big bang, equal, and that the speed of light has gradually slowed over time.

      I think the answer the author would give to your question is that the "gravity waves" you mention would arrive before the light would, but it would not be instant.

      -bs

      • gravity is a force. it produces acceleration. Using

        F=ma,

        where the mass of earth is 5.9742 × 10^24 kilograms, in order to get an acceleration of 1 meter per second squared toward these black holes (now this black hole), they would need to exert a gravitational pull of

        5.97 x 10^24 meters per second squared, or very roughly 10^24 times earth's gravity.

        This rough calculation does not include the (small amount of) friction present in space, or opposite gravitational pulls from other objects. Plus

        • Re: (Score:3, Informative)

          by account_deleted ( 4530225 )
          Comment removed based on user account deletion
        • Wha? The word "gravity" by itself isn't a force. It's a concept. The "force of gravity" is the force felt by two objects pulling on eachother, which you could calculate using (G(m1)(m2))/(r^2). Since we can calculate the mass of the black holes based on the speed of the dust orbiting a particular distance from the center, we could find the real force that the black holes exert on the earth (which, yes, would be small, since the objects are so far away). The problem, though, is that since the black holes a
      • It's worth bearing in mind that the varying speed of light (VSL as the author puts it) is still considered a crackpot theory, and the book is written by the same person who put it forth. I'm not saying it wasn't an interesting read though.
      • Gravity used to go the same speed as light, but then it pissed off Chuck Norris and has to go faster now to get away.
        • Gravity used to go the same speed as light, but then it pissed off Chuck Norris and has to go faster now to get away.

          Heresy!
          You're claiming something managed to get away from Chuck Norris?!?
          No, my friend, it pissed off Chuck Norris who roundhouse kicked it past the speed of light.

    • Will it really matter? Their respective gravity wells are already in (relative) proximity. when they converge There shouldnt be a huge gravity spike or anything should there?
      • If you consider that the Earth/Moon gravitational playground affects the very earth we stand on.
        It is strong enough to move the oceans, and thats just a tiny moon around a tiny star at the outer edge of a smallish galaxy.
        Imagine how the tidal forces of these two monsters would be playing and distorting and twisting their surroundings.
        Hurling entire star systems great distances at a time, suddenly one system comes out from behind the shadow of another system and is thrown into the path of an oncoming blackho
    • never mind.. I just RTFA.

    • Re:Sooner than you think (Score:5, Informative)

      by Luyseyal ( 3154 ) <swaters@NOSpAm.luy.info> on Friday April 07, 2006 @12:33PM (#15085898) Homepage
      Scientists measured the speed of gravity [newscientist.com] a few years ago... short answer: it travels at the speed of light as predicted by Einstein's equations.

      Cheers,
      -l

    • According to this http://www.space.com/scienceastronomy/gravity_spe e d_030107.html [space.com] Gravity travels at light speed.

      However, it was immediately attacked http://www.space.com/scienceastronomy/gravity_spee d_030116.html [space.com]

      Contrary to some of the other posts there is no current reason to exclude the idea that gravity is faster than the speed of light. Some experiments have shown that it is possible. ( http://physics.about.com/cs/gravity/a/speedofgravi ty_2.htm [about.com] ) We do not know what gravity is, exactly, so its impo

      • Comment removed (Score:5, Informative)

        by account_deleted ( 4530225 ) on Friday April 07, 2006 @03:03PM (#15087290)
        Comment removed based on user account deletion
        • 'Mod parent down: -1 nonsense.'

          Err thanks.

          'The article to which you link mentions a paper by Kopeiken that has been discredited.'

          Really? How'd you work that out? Was it from the second link I posted discrediting him perhaps...

          'Measurements of binary pulsars, the canonical example of which is PSR B1534+12, have demonstrated that the speed of gravity is equivalent to the speed of light to within +/-1.5%.'

          Yes and the study I posted, while less accurate, said more or less the same thing.

          'Quite apart from these
          • Comment removed based on user account deletion
            • No, my first claim was that there were studies proving gravity moves around light speed.
              My second claim was that there are also studies proving these are flawed.
              My third claim was that there is no reason to exlude the idea that it moves faster than light.
              My fourth claim was that we just werent entirely sure.

              and not one of them is inacurate. There _are_ studies proving and attacking all of our current methods of measuring its speed. There _isnt_ as far, as I am aware, hard evidence that it moves at the speed
    • Consider that the speed of light really is just the maximum speed at which causality can propogate and you'll understand why gravitational effects cannot propogate faster.

      Now whether gravity can propogate slower than light would be an interesting question.

    • Speed of gravity (Score:1, Informative)

      by Anonymous Coward
      Replying in one place regarding several responses.

      First, the speed of gravity was measured decades ago, inferred by the rate at which the orbits of two neutron stars in a binary pair decayed. The rate of decay agreed exactly with what general relativity predicts due to energy loss via gravitational radiation traveling at the speed of light. The 1993 Nobel Prize was awarded for this work. See this FAQ [ucr.edu].

      Some poster mentioned Magueijo's work; it is, to put it politely, not well accepted. In point of fact, t
    • Umm, how many light years away is this? Sure, it might take million years for the *light* from the spectacle of them merging to reach us, but if they're millions of light years away (center of the galaxy?), they may have already merged.

      Time is all relative. The idea of "simultaneity" gets more and more ambiguous as distances increase. Does the fact that something is happening "now" even matter, if the effects of that occurrence can't reach us in less than millions of years? The entire concept of "now" lo

  • What...Goatse Guy met Tubgirl? (Score:5, Funny)

    by R2.0 ( 532027 ) on Friday April 07, 2006 @11:37AM (#15085193)
    Come on - tell me no one else thought of that?
  • That could also be a good title for a porn flick!
  • How else are they going to figure out what to do with the stuff which is left over after their pairing collapses?

  • Stop! (Score:4, Funny)

    by Hikaru79 ( 832891 ) on Friday April 07, 2006 @11:44AM (#15085280) Homepage
    Fortunately they've still got several million years for the emotional rush to wear off and realize what a terrible mistake they're both making...

    Black holes hate it when you anthropomorphise them!

  • something I always wondered (Score:3, Interesting)

    by Fëanáro ( 130986 ) on Friday April 07, 2006 @11:58AM (#15085450)
    Something I always wondered:
    When two black holes are close together, then something that has exactly the same distance to each of them should not fall into either one.

    What happens when they are so close that their event horizons overlap?

    Shouldn't there always be some flat zone between them that is not part of either event horizon?

    So how can they merge?
    • I'm just speculating here, but I'm betting you have a RAZOR thin 'line' between the two. You're still squished into spaghetti at that line, and once they 'touch' event horizons, it's only a (short?) matter of time before their center's merge and form one, larger black hole, whith one, larger event horizon. It's not like there is any force that will cause them to repell one another, so they likely arc together in an ever tightening vortex until they merge. The closer they get, the faster they go, as well.
      • Well, at the "line", they would cancel each other out exactly, but close to the line they would still almost cancel each other out, so a small object might be able to hold together there. It would be an instable position, but a small spaceship might be able to maintain that position?

        What if they don't collide exactly head-on, but just circle each other? They would circle closer and closer, whithout ever actually coliding, so would this "line" stay?
        • See wikipedia on black holes. Any spinning black hole has a ring-shaped singularity. Anything that sits on the line thru the center will never hit the singularity, but everything else will. *cue twilight zone theme*
        • It would be an instable position, but a small spaceship might be able to maintain that position?

          I'd have to give a big resounding no. IANAAP (I Am Not An Astrophysist), but it would be generally assumed that since we are 3 dimensional, some of our atoms would fall on one black hole's event horizon and then some on the other resulting in the space craft and those inside of it to be ripped into two bits sans the atoms that fall along the razor edge.

          However, if you were a 2d entity, you might be able to pull t
          • However, if you were a 2d entity, you might be able to pull this off... But I'm not sure how a 2d entity can survive in a 3d world much less transport itself between two black holes.

            Wasn't that covered in a ST:TNG episode?

        • Well, at the "line", they would cancel each other out exactly, but close to the line they would still almost cancel each other out, so a small object might be able to hold together there. It would be an instable position, but a small spaceship might be able to maintain that position?

          You'd be ripped in half.
        • What do you mean by a "small" spaceship? Compared to what?
        • The area where they "almost" cancel each other out wouldn't be large enough to worry about as the tidal forces are extremely intense near a black hole. In fact, they are strong enough that you would be torn apart by just falling into a single black hole, you don't need the tug of another singularity to do the damage.
    • when two black holes are close to each other they become surrounded by a common horizon and for all practical purposes they look like a distorted black hole

    • Re:something I always wondered (Score:4, Informative)

      by Bob3141592 ( 225638 ) on Friday April 07, 2006 @12:33PM (#15085897) Homepage
      Something I always wondered: When two black holes are close together, then something that has exactly the same distance to each of them should not fall into either one. What happens when they are so close that their event horizons overlap? Shouldn't there always be some flat zone between them that is not part of either event horizon? So how can they merge?

      There's a difference between the strength of a gravitational field and a gravitational gradient. It's like at the center of the Earth. The gravitational gradient there (relative to the Earth's field) is zero, but the force of all that overhanging rock is pretty high. You wouldn't float there comfortably with no force acting on you. You'd be squished.

      And that's in a conventional, Nwtonian view of gravity, which is where most people are comfortable thinking about these things. In the relativistic world things get a bit more complicated. The gravitational field itself has energy, and energy at sufficiently high densities has an appreciable mass equivalence and so itself gravitates. At high enough values, like at the event horizon of a black hole, this kind of positive resonance causes the equations describing the system to diverge and the solutions go to infinity, and this divergence is called a singularity.

      The event horizon isn't a physical thing, it's the point where the divergence is assured. You can't really think of a black hole as a single hard little ball agt the center of a black hole surrounded by black empty space up to the event horizon, though I believe that's now most people think of it. All spatial and temporal points within the event horizon are indistinguishable - but it's be somewhat misleading to say that they're all the same point either, because the equations that describe those points can't be solved rationally since they contain infinities and it's like asking how infinity +1 is different from infinity + 2.

      If you were able to maneuver in space such that you were always equidistant from two black holes of identical mass, you would float around comfortably as long as the bh's were sufficiently far from you. As they approached, you'd feel significant tidal stretching. As the bh's got closer, you would be stretched further, and smaller regions even closer to that exact midpoint would feel increased stretching. At the point where they merged, even the infinitestimal point at the exact center would be stretched to infinity (that one zero volume point could not resist the force that was stretching it out to fill the volume of the whole universe). Of course, this is a somewhat poetic way to describe events that cannot really be described because the physical equations contain infinities and have no meaningful interpretations.

      At times like that, poetry is all you can do. It's hard to resist making analogies with this scenario and the creation of the universe, but such analogies, like any other analogy what talk about on or inside the event horizon of a black hole, are meaningless here. But it's still fun.

      • Wow. After that explanation I think I need a cigarette.

      • Comment removed (Score:5, Insightful)

        by account_deleted ( 4530225 ) on Friday April 07, 2006 @03:16PM (#15087395)
        Comment removed based on user account deletion

      • There's a difference between the strength of a gravitational field and a gravitational gradient. It's like at the center of the Earth. The gravitational gradient there (relative to the Earth's field) is zero, but the force of all that overhanging rock is pretty high. You wouldn't float there comfortably with no force acting on you. You'd be squished.

        Doesn't Newton's shell theory state that when within a large spherical body of mass you can treat the mass as a shell of radius to where you are within it be

        • Nope, the gravitational attraction of all the Earth's mass points in one direction: down. When you are at "down", you've got 5.972e19kg of rock trying to get to where you are. It wouldn't be pretty. (Although the strength of the gravitional field does drop as you approach "down", at no point does it reverse, let alone strongly enough to counteract weight of the outer mass). A hollow earth isn't stable, either. Especially for a mostly-liquid mantle. As soon as the center of the hollow sphere (the "bubble")
        • To paraphrase the above: If the center of the Earth was hollow, then there wouldn't be any rocks there, so there wouldn't be any rocks to squish you.

          (but it's not hollow, so there are rocks there, so they would.)

          And this is currently up to +3 Insightful how?

          There is no "mass canceling out" involved. Even though in a hollow shell, the gravetational attractions for rocks in the shell on you at the center all cancel, the gravitational attractions of those rocks on each other don't, so big hollow shells of rock

      • Re:something I always wondered (Score:4, Informative)

        by ScriptedReplay ( 908196 ) on Friday April 07, 2006 @04:03PM (#15087802)
        There's a difference between the strength of a gravitational field and a gravitational gradient. It's like at the center of the Earth. The gravitational gradient there (relative to the Earth's field) is zero, but the force of all that overhanging rock is pretty high. You wouldn't float there comfortably with no force acting on you. You'd be squished.

        ouch! no. At least, not if you assume spherical symmetry. Baby analytical mech. example: the uniform sphere. Gravitational force is linear inside, going to zero.

        You'd be squashed, alright, but not by gravity. It's the pressure in all that rock around you that you have to watch for. But if you manage to stabilize the hole you supposedly dug in the center of the Earth against the surrounding pressure, then you'd be floating quite comfortably.
    • There is nothing magic about the event horizon of the black hole. When two things pass an equal distance from any two objects that are big enough that they would normaly fall toward one thing or the other, the net force is zero. This is not to say that the force on the object is zero however, and if something passed between two black holes that were close to each other, they would be ripped in half. Due to the massive forces involved, however, people invariably talk of a slice of atoms that are in the ex
      • In the fraction of those atoms in the center plane who ARE exactly blanced

        Then you hit a problem when the electron moves to a different position, throwing off the balance. Or maybe in this position, the electron gets ripped off in one direction and the nucleus goes another -or part of the nucleus goes one way and part goes the other...

    • Re:something I always wondered (Score:3, Informative)

      by Anonymous Coward
      The event horizon of a black hole can be thought of as the surface from which no information (particles, energy, whatever) can escape. It's the event horizon because it's where observable events (time) ends; you can't see what happens inside a black hole.

      Now, merging black holes. If you're in the exact center (or maybe not the very exact center, since black holes drag space-time around them and other funky effects), then maybe you don't get "pulled" into either black hole before the merger. But you still
    • In a perfect, hypothetical universe of infinite size which contained only those two black holes, and if both were far enough apart that you and your ship could be centered between them without being close enough to either black hole for the gravity to tear you / your ship apart, yes, maybe you could maintain a central position. Given those two, there's the third problem of movement...The two black holes will be in motion, and it while you may be able to calculate where the 'safe spot' will be at a given in
  • Anyone running odds on which one eats the other? Or what happens post eating?
    • I will bet anyone any amount they want as long as I get to hold the money until we discover the outcome in a few million years.
  • that '80s classic, Mondern English's I Melt With You? A pair of dancers whirling together in the darkness...

    Meh, I must be getting sentimental in my old age.

  • CNN.com reports on a pair of black holes in a mating dance

    Sounds like there's a party at the Goatse guy. :-S
  • I dunno, but here on Earth, mergers of Supermassive companies usually end up in additional service charges.

    - RG>

  • If I was sufficiently advanced (Score:3, Funny)

    by cnflctd ( 69843 ) <tom.j.lambrecht@NosPam.gmail.com> on Friday April 07, 2006 @12:20PM (#15085745)
    Two supermassive black holes are spiraling closer and closer, leading to an inevitable merger.

    But is it really inevitable, I ask myself? What would it take to pry them apart? Welcome to einstein's tractor pull!

    Imaging the black holes 1 and 2 falling straight towards each other. (Trying to do this with them spinning makes my head hurt). You take a third supermassive BH, call it 3, and give it a large velocity relative to the other two. Send it thru the system at a slight angle.

    As it hurtles by the hole 1, it drags it along -- has to come real close, but not too, noam sayin?

    As 1 and 3 zip by 2, 1 gets slowed down some, but still has excape velocity from 2. See? No sweat. Now if DARPA will give me a grant, I'd hire a math major to solve orbiting BH case.

    • But is it really inevitable, I ask myself? What would it take to pry them apart? Welcome to einstein's tractor pull!

      Imaging the black holes 1 and 2 falling straight towards each other. (Trying to do this with them spinning makes my head hurt). You take a third supermassive BH, call it 3, and give it a large velocity relative to the other two.

      Man, I always hated word problems. So ... which one is leaving Chicago again?

  • "Can only end badly"? (Score:4, Funny)

    by ElMiguel ( 117685 ) on Friday April 07, 2006 @12:29PM (#15085849)
    They are black holes. How much worse can it get?

  • "The funny part, was when the Black Holes collided."

  • Let it bee let it beee let it beee oh let it beeeee -aslongasitdoesntdestroythewholeuniverse- let it beeeeeee eeee
  • My astrophysics professor actually does work simulating black hole collisions. There are some cool images and movies of galaxies containing black holes colliding at http://web.phys.cmu.edu/~tiziana/BHGrow/ [cmu.edu]

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