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NASA Achieves Breakthrough Black Hole Simulation 281

Posted by ScuttleMonkey
from the pretty-pictures dept.
DoctorBit writes "NASA scientists have achieved a breakthrough in simulating the merging of two same-size non-spinning black holes based on a new translation of Einstein's general relativity equations. The scientists accomplished the feat by using some brand-new tensor calculus translations on the Linux-running, 10,240 Itanium processor SGI Altix Columbia supercomputer. These are reportedly the largest astrophysical calculations ever performed on a NASA supercomputer. According to NASA's Chief Scientist, "Now when we observe a black hole merger with LIGO or LISA, we can test Einstein's theory and see whether or not he was right.""
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NASA Achieves Breakthrough Black Hole Simulation

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  • by Douglas Simmons (628988) * on Wednesday April 19, 2006 @11:30AM (#15157491) Homepage
    From the article: "when two massive black holes merge, all of space jiggles like a bowl of Jell-O"

    Wouldn't Kraft Foods have prior art on this?
  • Finally.... (Score:2, Funny)

    by smaerd (954708)
    ....a machine that can tell me where my lost left socks have gone!
  • by Anonymous Coward on Wednesday April 19, 2006 @11:31AM (#15157508)
    "Itanium chips actually get used"
    • a year ago Itanium2 actually lead the floating point benchmarks, they do after all have a vector supercomputer architecture. But of course with delays and scaling back the operating frequencies, the dual cores still aren't out yet and the clock will be about the same, 1.6 GHz as the older models. So unless intel does something really suprising and stellar, I don't see Itanium leading in the supercomputing field anymore, and SGI is stubbornly refusing to consider AMD, so the chip and SGI may soon be toast
  • by Nom du Keyboard (633989) on Wednesday April 19, 2006 @11:32AM (#15157527)
    How about something more useful to everyday life?

    The catastrophic results of merging Microsoft and Linux?

    The hilarious results of merging Intel and AMD.

    The unexpected results of merging a spinning Steve Jobs (Intel is Evil/Intel is the best, brightest, future of Apple) and the O'Reilly No-Spin Zone.

    Those I'd buy tickets for.

    • According to TFA The scientists accomplished the feat by using some brand-new tensor calculus translations on the Linux-running, 10,240 Itanium processor SGI Altix Columbia supercomputer.

      They finally managed to use up all of those Itanium processors hanging about in storage. Well done!


    • Seriously, I'd imagine there are a total of probably 30 people on earth who understand the math behind what's going on here. Not really news, even for nerds.
  • by Xest (935314) on Wednesday April 19, 2006 @11:33AM (#15157536)
    What kind of framerate do you get on that machine when playing Half-Life 2?
  • by rewinn (647614) on Wednesday April 19, 2006 @11:33AM (#15157541) Homepage
    ...would he have developed General Relativity sooner, or just played WarCraft?
  • by Anonymous Coward on Wednesday April 19, 2006 @11:34AM (#15157545)
    Based on observations, what percentage of black holes are non-spinning vs spinning?
    • by hunterx11 (778171) <`hunterx11' `at' `gmail.com'> on Wednesday April 19, 2006 @11:40AM (#15157615) Homepage Journal
      "Rotating black holes are thought to be formed in the gravitational collapse of a massive rotating star or from the collapse of a collection of stars with an average non-zero angular momentum. Most stars rotate and therefore it is expected that most black holes in nature are rotating black holes." Rotating black hole - Wikipedia [wikipedia.org]
      • by loudambiance (935806) on Wednesday April 19, 2006 @12:13PM (#15157900)
        According to theory, the event horizon of a black hole that is not spinning is spherical, and its singularity is (informally speaking) a single point. If the black hole carries angular momentum (inherited from a star that is spinning at the time of its collapse), it begins to drag space-time surrounding the event horizon in an effect known as frame-dragging. This spinning area surrounding the event horizon is called the ergosphere and has an ellipsoidal shape. Since the ergosphere is located outside the event horizon, objects can exist within the ergosphere without falling into the hole. However, because space-time itself is moving in the ergosphere, it is impossible for objects to remain in a fixed position. Objects grazing the ergosphere could in some circumstances be catapulted outwards at great speed, extracting energy (and angular momentum) from the hole, hence the name ergosphere ("sphere of work") because it is capable of doing work. Once all the angular momentum is extracted from a spinning black hole, what do you think happens, it stops spinning.
        • Hmm, this begs the question. Do the simulations for a non-spinning black hole approximate a very slowly spinning BH, or is it a step function, spinning vs. non-spinning? Since just about everything in the universe has some angular momentum, you'd think all BH'es would be spinning with the older ones just doing it very slowly.

          Another question would be: Can the ergosphere apply energy to the BH making it spin faster? I.E. If a body crashes into the ergosphere almost grazing, but is captured, does it tr
        • According to theory, the event horizon of a black hole that is not spinning is spherical, and its singularity is (informally speaking) a single point. If the black hole carries angular momentum (inherited from a star that is spinning at the time of its collapse), it begins to drag space-time surrounding the event horizon in an effect known as frame-dragging. This spinning area surrounding the event horizon is called the ergosphere and has an ellipsoidal shape. Since the ergosphere is located outside the eve
      • Most stars rotate and therefore it is expected that most black holes in nature are rotating black holes."

        I think you'll find it a given that ALL stars rotate..., even if some rotate very slowly or they're too far away for us to detect the rotation signature in their spectra, but they ALL rotate

    • The reason for doing a non-spinning black hole is that it's an easier calculation to make. Once they have some experience with this simulator I'm sure they will move on to spinning black holes.


      • Once they have some experience with this simulator I'm sure they will move on to spinning black holes.


        True. In fact, some steps have already been taken in this direction by other groups. For instance, my group at U.T. Brownsville -- whose non-spinning simulations were published simultaneously with the NASA results (but we don't have the same PR machine) -- have put up a preprint on the orbits of black-hole binaries where the individual holes have spins parallel to (or antiparallel to) the orbital angular mo
  • ... non-spinning black holes ...

    Must've been playing Nowhere Man [lyricsfreak.com] in the background when they came up with this idea.
  • by Rik Sweeney (471717) on Wednesday April 19, 2006 @11:39AM (#15157605) Homepage
    Now when we observe a black hole merger with LIGO or LISA, we can test Einstein's theory and see whether or not he was right.

    And if he's wrong then all the scientists can make "loser" signs at him on their foreheads...
  • by bigwavejas (678602) on Wednesday April 19, 2006 @11:40AM (#15157614) Journal
    anyone know if google has a science-nerd-jargon translator?
    • "NASA scientists have achieved a breakthrough in simulating the merging of two same-size non-spinning black holes based on a new translation of Einstein's general relativity equations. The scientists accomplished the feat by using some brand-new tensor calculus translations on the Linux-running, 10,240 Itanium processor SGI Altix Columbia supercomputer. These are reportedly the largest astrophysical calculations ever performed on a NASA supercomputer. According to NASA's Chief Scientist, "Now when we observ
  • by HiddenL (967659) on Wednesday April 19, 2006 @11:41AM (#15157619)
    Now when we observe a black hole merger with LIGO or LISA, we can test Einstein's theory and see whether or not he was right.
    More likely: Whether or not the equations used are a correct approximation for Einstein's equations.

    And even more likely: Whether or not the computers performed the calculations correctly (the chips are made from Intel, and we all know the history of Intel screwing up floating point math)
    • The simplest tensor calculus equations require thousands of lines of computer coding. The expansions, called formulations, can be written in many ways. Through mathematical intuition, the Goddard team has found the appropriate formulations to lead to suitable simulations.

      More like, did they guess right with their "mathematical intuition" in creating the computer code. Or did they just muck with it until they got a pretty video that wouldn't crash the system. This could be just another NASA problem with
    • by Surt (22457) on Wednesday April 19, 2006 @12:28PM (#15158052) Homepage Journal
      This is really not the case.

      First, with regard to intel, there is essentially no risk from this, as the math libraries used by everyone involved in such work wave test exercises that verify the accuracy of the hardware. It's not uncommon to run every calculation on two physical processors to assure that no single processor malfunction can introduce a significant error.

      Second, with regards to the correct approximation of Einsteins equations, either the approximation is exact, in which case there is no risk, or the error size for the approximation is closely known, in which case when we observe the black hole merger, we will have one of 3 conditions: confident to some error size that he was right (actual results match simulation, but we can't rule out his theory being slightly wrong at a finer level), confident that he was wrong (actual results lie outside of error range for simulation), or no result (actual results indicate the possibility he was wrong, but lie within error range).
    • How often do we hear - "And the real world observations are EXACTLY what scientists predicted" versus "Based on these unexpected results, scientists will have to go back to the drawing board"
  • That's new to me. (Score:4, Interesting)

    by ErikZ (55491) on Wednesday April 19, 2006 @11:42AM (#15157627)
    Non spinning black holes?

    Is there such a thing?
    • Non spinning black holes?

      Is there such a thing?


      Can a single point spin?

      Although, I don't know if the center of a black hole is more than a single point
      • Spin is one of the fundamental identifying characteristics of a black hole (in addition to mass and electric charge). Also, if I understand correctly, not all of the mass is necessarily contained at the singularity.
  • OAQ (Score:5, Funny)

    by LouisZepher (643097) on Wednesday April 19, 2006 @11:42AM (#15157634)
    Not mentioned in the article of course, is that shortly after the simulation, the software collapsed in on itself as it underwent a Massive Total Existence Failure.
  • Ick! (Score:4, Funny)

    by Rob T Firefly (844560) on Wednesday April 19, 2006 @11:48AM (#15157670) Homepage Journal
    TFA: when two massive black holes merge, all of space jiggles like a bowl of Jell-O

    Watching massive things merging.. jiggling like jell-o... Good heavens, space is a pervert!!!

    • Watching massive things merging.. jiggling like jell-o... Good heavens, space is a pervert!!!

      I don't think it's space/the universe which is being a pervert. Just FYI. ;-)
  • They're not black holes, they're just a result of Intelligent Darkness. Seriously, why do we teach kids today the theory of black holes without not also teaching them about Intelligent Darkness?
  • by rotenberry (3487) on Wednesday April 19, 2006 @11:55AM (#15157735)
    Scientists has been doing similar calculations for a long time. For example

    Larry Smarr, "Gravitational Radiation from Distant Encounters and Head-On Collisions of Black Holes: The Zero Frequency Limit," Phys. Rev., D15, 2069-2077, 1977.

    I cite this paper because Larry Smarr is one of the Nasa panelists for this project, and I heard his talk on this paper at the University of Texas at Austin in the late 1970s. Come to think of it, I remember seeing one of the other panelists, Joan Centrella, at the same talk.
  • by Urban Garlic (447282) on Wednesday April 19, 2006 @11:56AM (#15157741)
    OK, I'm no general relativist, but I am a computational physicist -- what could the article possibly mean when it says earlier attempts were "plagued by computer crashes -- the equations were far too complex"?

    I can imagine a situation where a poorly-arranged computation of an equation might give you an underflow in an intermediate result, or where a badly-arranged summation might give you noise. But crashing the computer? Sounds more like array-bounds, which can happen no matter how simple the equations are.
    • by augustm (147506) on Wednesday April 19, 2006 @12:19PM (#15157965)
      A major technical problem of integrating field equations is in
      the propagation of /constraints/ on the components. Ie GR
      describes the time evolution of a tensor for which all the
      components are not independent- for instance they obey
      Bianchi identities.
      http://mathworld.wolfram.com/BianchiIdentities.htm l [wolfram.com]


      Simple numerical integrators destroy these identities
      at order dt^n for some small but finite n. Run the code
      forwards and one can find finite time blow ups due to
      the stepping algorithm- however even after a single
      time step the numerical solution has unphysical aspects


      Finding /constraint conserving/ algorithms is tricky
      http://www.ima.umn.edu/nr/abstracts/6-24abs.html [umn.edu]

    • OK, I'm no general relativist, but I am a computational physicist -- what could the article possibly mean when it says earlier attempts were "plagued by computer crashes -- the equations were far too complex"?

      The article is a bit wooly. Basically, Einstein's equations are a system of constrained partial differential equations. The horrible thing about them is that they are all coupled and nonlinear too. There exist several mathematical ways to analyse these sorts of things in the continuum, mainly cent
    • But crashing the computer? Sounds more like array-bounds, which can happen no matter how simple the equations are.

      "Black holes are where God divided by zero." -- Steven Wright
    • My guess is that they would mean crashing the simulation or crashing the model, in other words: "And the answer is... NaN".
  • by metamatic (202216) on Wednesday April 19, 2006 @12:29PM (#15158069) Homepage Journal
    That's nothing--the WB and UPN are merging in September, producing a vortex of TV so sucky that not even brain cells will be able to escape.

    The interesting question is whether the CW black hole will rotate or not. I for one hope that TV execs will be able to sit on it and spin.
  • This sounds more like a "milestone" then a "breakthrough". non-spinning sounds like a huge simplifying assumption as I doubt there are many non-spinniong black holes except for very, very small ones.
  • by kurbchekt (890891)
    This isn't the only testing that NASA is doing of Einstein's theories. For those that are interested, there is also the Gravity Probe-B [stanford.edu]. Really interesting stuff!
  • Stats.. (Score:2, Informative)

    by modi123 (750470)

    In case anyone was wondering how Columbia stacks against their rig, check out:

    http://www.top500.org/ [top500.org]

    Here's the November 2005 list:

    http://www.top500.org/lists/2005/11/TOP10_Nov2005. pdf [top500.org]

    It shows Columbia with:

    51.87 Rmax (teraflops/second).. It also states that it moved from #3 ranking to #4.

  • "Now when we observe a black hole merger with LIGO or LISA, we can test Einstein's theory and see whether or not he was right."
    I'm reserving my seat tickets for 12,006 A.D right now. I'll just will them to my descendants.
  • What, they sent another budget request to Congress ? :-)
  • If these scientists are not careful, they could start a chain reaction and convert ALL of cyberspace into one big blackhole!!
  • If the simulation results seem to say that Einstein was wrong, that still doesn't prove that he was wrong, because they have not actually merged two black holes together in the real world. Simulation != real world. If there are any flaws in the assumptions, parameters, or algorithms they use to perform the simulation, then it invalidates the whole exercise.
  • The oontributions of Einstein never cease to amaze me.

    Decades after his death, they're still finding new ways to look at his work, and really appreciate the stuff he did work out. And much of what he said still seems to turn out to be right.

    I'm fairly sure I can't accurately predict what will be for dinner tonight, let alone how the whole freaking Universe seems to work.

    Ah well, if he was wrong about everything, he probably wouldn't be nearly as famous. =)
  • by ChenLing (20932) <.slashdot. .at. .ilovedancing.org.> on Wednesday April 19, 2006 @04:03PM (#15160015) Homepage
    I'm a recent member of this group, so I'd like to put in my 2 cents.

    1) This is a first -- no other group has achieved this before. yay! (after decades of work!)

    2) This is hard for the following reasons:
        a) since you are doing calculations near (or on/in) a black hole, you tend to get a lot of
              infinities, which 1) crash your code and 2) exacerbate your errors
        b) for most simulations, your grid remains fixed. For black holes though, they *deform* the
            spacetime around them -- which means your grid points have to move (in a non-predictable
            manner)!
        c) what happens when two black holes merge is not well understood (ie, what should happen?),
            so this is new science
        d) initial data is hard to get and unreliable. If two black holes are far apart, you can
            write an exact solution (at least within some error), but to get them close to where they
            are interating, you pretty much need this kind of simulation anyways. This is such a large
            problem that there are only a handful (a dozen or two?) initial data sets currently.

    3) Everything is written in Fortran! :) (some competing groups use Cactus which is C++ based, although it also allows C and Fortran).

    4) It runs on a variety of architectures (x86, Itanium, PA-RISC, Alpha, etc etc)...pretty much
    anything that supports ifc (faster) or gcc.

    5) There are several approaches to some of the issues above, from puncture splitting (using a
    different spacetime metric like 1/r vs r to remove the singularity), excision (not evolving
    inside the event horizon, since that's not "interesting" anyways), and other methods. Our
    new method actually doesn't need any of those "tricks", which is pretty interesting.

    6) This data helps drive the LISA and LIGO projects from a theoretical standpoint--basically
    knowing what kind of gravitional waves they should be seeing, and to correlate what they see
    and what their data may represent (ie, if you see a waveform like this, this means that it's
    two merging black holes, vs just co-rotating black holes).
    6a) We study black holes b/c they are pretty much the only thing that'll generate detectable
    gravitational waves.

    so yay!

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