NASA Achieves Breakthrough Black Hole Simulation

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.""

IP violation

[Douglas Simmons (628988)]

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?

Yes.

[Vandilizer (201798)]

And I whole heartily encourage all patent and IP lawyers to go to those black holes and ether Subpoena them or deliver a notice of possible infringement.

This should solve all lot of problem here on earth as well, if we can get them to all go.

Unless that is the Black hole decides to show up for its court date.

Headline should read:

[by Anonymous Coward]

"Itanium chips actually get used"

How about something more useful?

[Nom du Keyboard (633989)]

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.

I think what we really want to know is...

[Xest (935314)]

What kind of framerate do you get on that machine when playing Half-Life 2?

Meh

[ichigo 2.0 (900288)]

HL2 is singlethreaded so the performance would be the same as on one Itanium. Also x86 code has to be emulated on Itaniums = slow. Oh and no GPU which means pixel/vertex shaders would have to run on software. Educated guess: 0.1 fps.

If Einstein had had those supercomputers ...

[rewinn (647614)]

...would he have developed General Relativity sooner, or just played WarCraft?

Are there non-spinning black holes?

[by Anonymous Coward]

Based on observations, what percentage of black holes are non-spinning vs spinning?

Re:Are there non-spinning black holes?

[hunterx11 (778171)]

"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]

Re:Are there non-spinning black holes?

[loudambiance (935806)]

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.

And if Einstein is wrong...

[Rik Sweeney (471717)]

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...

translate article

[bigwavejas (678602)]

anyone know if google has a science-nerd-jargon translator?

Are they really testing what they think?

[HiddenL (967659)]

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)

Re:Are they really testing what they think?

[Surt (22457)]

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).

That's new to me.

[ErikZ (55491)]

Non spinning black holes?

Is there such a thing?

Re:That's new to me.

[OverlordQ (264228)]

Can't even spell Coriolis yet we're supposed to believe you know about black holes and physics regarding them?

OAQ

[LouisZepher (643097)]

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!

[Rob T Firefly (844560)]

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!!!

Equations too complex?

[Urban Garlic (447282)]

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.

Re:Equations too complex?

[augustm (147506)]

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]

Black hole simulation

[metamatic (202216)]

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.

From a member of the group

[ChenLing (20932)]

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!

Re:Wasted funding?

[hswerdfe (569925)]

What is the actual outcome from this research?
more knowledge about the universe and how it might work.

Will this help create more energy-efficiency in the world?
maybe, who can say what future developments and understanding of this area of physics will bring.

Will it help us find technology that humanity can actually use to make a better society?
maybe, see above. it depends on the definition of "better".
when general relativity was first thought of in 1915 there was no application, for the average person. today GPS relies on general relativity.

Will it increase our safety, or decrease power of madmen and dictators?
the obvious answer is probably not. and while these are important questions, this one is not topical in this discussion.

Re:Wasted funding?

[A.K.A_Magnet (860822)]

How about making science progress by testing a part of one of the most important theory in physics? It's not my funding, however I'd love my country to invest more in science even if only for the sake of science. We're in an era where everything has to be justified by money, it feels like the Dark Age of information. I'm waiting for the next era where new thoughts, science and knowledge progress get some value back.

Call me utopist if you want, but finding something that "increase our safety, or decrease power of madmen and dictators" gets the #1 naive award (always thinking big shields and weapons, what a world).

Re:OK... Wait...

[republican gourd (879711)]

You use his theories to construct and run a model, and then you compare the results of that model to what you can observe in the sky. The differences between what is observable and what the model indicates are where the new knowledge is, even if things don't match up.