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Space Science

The Sound of a Black Hole 78

Posted by michael from the subwoofer dept.
Snags writes "Astronomers have used the Chandra X-ray Observatory to observe the deepest, lowest-frequency sound waves ever observed. By my calculations, the 'B-Flat 57 octaves below middle-C' has a period of 9.8 million years. Despite arguments that explosions in space movies should be silent, it is legitimate to call these sound waves because at that frequency, particles of space dust can 'see' each other through gravity. These notes are 'over a million billion times deeper than the limits of human hearing', so to call it infra-sound would be a bit of an understatement."
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The Sound of a Black Hole More

The Sound of a Black Hole

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  • That explains! (Score:5, Funny)

    by orkysoft ( 93727 ) <orkysoft@m y r e a l b ox.com> on Tuesday September 09, 2003 @07:11PM (#6915900) Journal
    Infrasound! Now that explains why many people have this irrational fear of black holes! :-)

  • My vivid imagination... (Score:4, Funny)

    by Anonvmous Coward ( 589068 ) on Tuesday September 09, 2003 @07:23PM (#6915985)
    When I read "The Sound of a Black Hole"
    the sound I heard in my mind was "oh shit there's a black hole!"

  • Wow - and I thought Germany had a long concert (Score:5, Interesting)

    by MerlynEmrys67 ( 583469 ) on Tuesday September 09, 2003 @07:46PM (#6916131)
    bbc.co.uk [bbc.co.uk]

    So this is a 639 year concert that has started in Germany. The concert has been ongoing for 17 months (the initial "quiet period" of the organ filling) however the first three note chord has been hit.

    Boy wish I had that kind of time to waste... Imagine the monks 630 years from now going - "Well, this is over now - what the hell are we going to do now ?"

  • GSS (Score:5, Funny)

    by falsification ( 644190 ) on Tuesday September 09, 2003 @08:22PM (#6916388) Journal
    B-Flat 57 octaves below middle-C

    AKA "a giant sucking sound."

  • B-Flat 57 octaves below middle-C? (Score:3, Funny)

    by Anonymous Coward on Tuesday September 09, 2003 @08:26PM (#6916412)

    B-Flat 57 octaves below middle-C, and it's the sound of a black hole. My , they've discovered the brown note!

    Umm, sorry for that...

  • No matter. (Score:5, Funny)

    by bobdotorg ( 598873 ) on Tuesday September 09, 2003 @08:54PM (#6916540)
    My extreme audiophile friend now has to replace his whole system to capture the experience of these new sounds.

    • Re:No matter. (Score:2, Funny)

      by mlush ( 620447 )
      My extreme audiophile friend now has to replace his whole system to capture the experience of these new sounds.

      Make that replace his whole Star system.

  • Why is everything good always in B-flat? The only good B-sharp ever was a Simpsons episode: Homer's Barbershop Quartet [snpp.com]. Ah, a classic. Now, where can I find Homer at the Bat [snpp.com]?
    • But isn't B# the same as C?

      Yeah, I know (you?) musicological types like to talk about B sharp or F flat or whatever, but I've never understood why.
      • I think it comes in useful when dealing with instruments whose key is not C. It makes transposing the key easier. In the final form, I guess they would be converted to the "actual" notes.
      • It depends on the scale you're playing in, if you're not playing in any particular key (just bashing on the keyboard) it doesn't matter which way you call the notes. The third note in a C-minor scale is E flat, and the second note in a C#-major scale is D#, and even so they're the same note. Play it on a piano and you'll see why the different names.

  • Alien (Score:2, Funny)

    by DeltaStorm ( 118517 )
    In space no once can hear you hum...
  • "These sound waves are thought to have been produced by explosive events occurring around a supermassive black hole (bright white spot) in Perseus A, the huge galaxy at the center of the cluster. The pitch of the sound waves translates into the note of B flat, 57 octaves below middle-C. This frequency is over a million billion times deeper than the limits of human hearing, so the sound is much too deep to be heard."

  • Concert (Score:5, Funny)

    by Molina the Bofh ( 99621 ) on Tuesday September 09, 2003 @10:08PM (#6917042) Homepage
    I wouldn't buy tickets to a music-playing blackhole concert. They suck.
  • Seems that Satchmo (Louis Armstrong) found his soul home. Of course, there have been other infra-bass singers, too. PRE
  • Seems that Satchmo (Louis Armstrong [satchmo.net] found his 'soul home' among the stars... PRE

  • play the "brown note" ?

  • On the team (Score:3, Interesting)

    by xiox ( 66483 ) on Wednesday September 10, 2003 @04:25AM (#6919205)
    I'm on the team that did this. Ask any questions you like!

    • Re:On the team (Score:4, Funny)

      by FrostedWheat ( 172733 ) on Wednesday September 10, 2003 @09:33AM (#6920492)
      I'm on the team that did this. Ask any questions you like!

      Would you like some toast?

      -Talkie Toaster

      • Re:On the team (Score:4, Funny)

        by xiox ( 66483 ) on Wednesday September 10, 2003 @02:58PM (#6923617)
        Look, I don't want any toast, and he doesn't want any toast. In fact, no one around here wants any toast. Not now, not ever. No toast!

        Or muffins! Or muffins! We don't like muffins around here! We want no muffins, no toast, no teacakes, no buns, baps, baguettes or bagels, no croissants, no crumpets, no pancakes, no potato cakes and no hot-cross buns and definitely no smegging flapjacks!
    • What's the error on the frequency of the note?

      • Re:On the team (Score:3, Informative)

        by xiox ( 66483 )
        Good question. If you look at the ripple image [cam.ac.uk] (generated by unsharp masking), you'll see the waves aren't perfectly spaced, so there's an error there. We estimate a wavelength of about 11 kpc. You then need the sound speed, which is a function of temperature (about 1170 km/s in gas of about 5 keV). The calculation of the period of 10^7 years is probably a good estimate, but it isn't precise. If you're really interested in the details read the original paper here [cam.ac.uk].
        • How can sound travel at 1170km/s through space, but only 340m/s at sea level?
          • The gas is actually a plasma (we tend to just call it gas in astronomy, though). It is much less dense than the air (there's only one atom per 10 or 100 cubic cm), and a lot hotter (around 50 million degrees). The atoms are ionised as many of the electrons have been stripped off the atoms.

            Roughly, the speed is so fast as the gas is hot. The particles move much faster and so they propagate any pressure fluctations faster.

    • What's the frequency in Hz?
      • The period of the wave is 9.6 million years. A quick calculation (haven't checked my sums) suggests the frequency is about 3.3 x 10^-15 Hz (or 0.0000000000000033 Hz)

  • Do black holes exist? (Score:3, Interesting)

    by nimblebrain ( 683478 ) on Wednesday September 10, 2003 @06:15AM (#6919488) Homepage Journal

    Black holes rely on an assumption that gravity has no limits on its strength, and to some extent on it following a strict Newtonian curve.

    Thinking of "curves" in space-time is an interesting analogy for gravity, but still doesn't address the mechanism - sure, the planet may be on a "45 degree" incline in spacetime, but what forces it down... and not up? You would nearly have to posit the existence of some constant stream of gravitons coming at 'right angles' to three-dimensional space in order to actually push things 'down the well'.

    There are alternate corpuscular (i.e. caused by particles; "quantum") models of the mechanism of gravity. There's the LeSagian model [wikipedia.org], with modern reworks that range from the bizarre-yet-possible theories of Tom Van Flandern, to the more "moderate" theories of Paul Stowe explaining how the "drag" factor that detractors expect doesn't show up, in exactly the sort of way that Feynman expressed it for electromagnetism.

    The LeSage-type theories are, in general, "push" theories, which operate in a medium filled with gravitons (just as space is filled with photons) that are deflected/absorbed near bodies and cast 'shadows' that create a low "pressure" area close to surfaces and, to a lesser extent, between bodies.

    The formulae calculate out approximately to Newton's/GR's gravity equation, but with some interesting exceptions:

    • There is a stronger fall-off at greater distances, which limits the effective range of gravity (surprisingly, this reduces the need for 'dark matter' to keep galaxies in the shape they're in)
    • Inside denser and denser bodies, graviton absorption reaches a point where matter on the inside hardly contributes at all (a complete gravity "shadow")

    This upper limit on the strength of gravity may prevent the ultimate collapse that black hole theory requires.

    Black holes are still a theoretical construct. Even the jets [nasa.gov], now often taken as a 'sign' of a black hole, are still a largely unexplained phenomenon, one that is also associated with accretion disks for newly-forming stars.

    So if something's singing in that cloud, it may not be as dense as it's accused of being.

    I apologize for all the jargon. I shall go read another thread on SCO as just punishment :)

    • Re:Do black holes exist? (Score:4, Informative)

      by Bonker ( 243350 ) on Wednesday September 10, 2003 @10:59AM (#6921320)
      Thinking of "curves" in space-time is an interesting analogy for gravity, but still doesn't address the mechanism - sure, the planet may be on a "45 degree" incline in spacetime, but what forces it down... and not up? You would nearly have to posit the existence of some constant stream of gravitons coming at 'right angles' to three-dimensional space in order to actually push things 'down the well'.

      The best explantion for this I've ever heard deals entirely with special relativity and never touches quantum mechanics. The author I read (Epstein) discusses what he calls 'Slow Time'. An object is always moving in four dimenions, even if it appears at rest to an observer, because it is moving forward in time as well. Since all dimensions of space and time are warped by the presence of matter, and not just space, if the object being observed is closer to a source of gravity (on a steeper part of the curve of space-time), he will start to experience time shortening or time dialation sooner and more strongly than you, the observer. His straight-line path through time starts to curve toward the source of gravity. This time-dialation acts as a vector force to 'push' him towards the source of gravity.

      You can read more about the interperatation of Special Relativity in this book: Relativity Visualized [amazon.com]
    • Doesn't a stronger fall off at greater distances actually go against the data we have for anomalous gravitational effects? If anything, both cosmological ("dark matter") and experimental data point to gravity being stronger than Newton at long distances.

      See also:
      "Study of the anomalous acceleration of Pioneer 10 and 11", Anderson, J.D., Laing, P.A., Lau, E.L., Liu, A.S., Nieto, M.M., and Turyshev, S.G., Physics Review D, v65, 082004, (2002)

      • The attenuation of gravity, according to one of the papers I ran across is about a kiloparsec, or about 3,300 light years from each single source.

        It can help get around the apparent contradiction that intact spiral galaxies present.

        Regardless, the attenuation is one of the predictions of one of the theories, and can be used to prove or disprove it. Currently, very little resources are being expended on such observations. Even Majorana's careful gravity shielding experiments have not yet been redone.

        Ot

    • Thinking of "curves" in space-time is an interesting analogy for gravity, but still doesn't address the mechanism - sure, the planet may be on a "45 degree" incline in spacetime, but what forces it down... and not up?

      That is the wrong question. Curvature is an intrinsic property of any spacetime; unless you are standing on something, there is no notion of down, up, or 45 degree incline. These notions arise only when using simplified "rubber-sheet" analogies to describe the effect of mass on the geomet

    • I don't know too much about the physics of gravity (yet), at least mathematically, beyond F=Gm1m2/d^2. However, my interpretation of general relativity was that a collection of mass (or energy) moves inertially through spacetime, that is, without inherent acceleration, and the acceleration we see occurs because the object is following the topology of space as it goes along. If spacetime is curved, the shortest distance between two points is some sort of curve.

      That's why I think the term "gravity well" is
  • Is this the Brown Note. Is it real?
  • I wonder what the energy associated with these sound waves are. It's got to be rather sizeable, right? I'm too far out of college to remember all my energy equations but still retaining enough to be curious.

    In a simplistic level, think of a stereo's tweeter speaker...short soundwaves that just hurt the ears if turned up too high. Then you've got the bass...longer soundwaves that you can feel the "punch". So I wonder what these soundwaves from the black holes are capable of doing. They've got to have some
    • We expect the waves to dissipate most of their energy in the inner 100 kpc (~300,000 light-years) of the cluster (if you look at the published images, that's about the region you see). The idea is this heating effect may be able to balance the cooling of the gas in the core of the cluster. Stopping the cooling means that the central galaxy doesn't grow much bigger.

      We expect the actual sound amplitude to be similar to that produced by a human voice!
    • I should add the even though the sound is as loud as a human voice, as it travels over a massive volume, there are very large amounts of energy involved.

      You need massive amounts of energy to heat the centre of a cluster and stop it cooling (an estimate is 10^36 erg/s).

    • Whoops! (Score:2)

      by xiox ( 66483 )
      Make that 10^36 Joules per s
    • One of the authors [slashdot.org] posted [slashdot.org] a link [cam.ac.uk] to the original paper. They say that the amplitude of the ripples is about 20-30% of the X-ray brightness. I don't know what density variations that corresponds to, but it sounds huge. The amount of energy carried by the wave would be correspondingly huge.
  • Thanks for the Harvard link! Here are some more images from Space.com. This one is a composite photo [space.com]. of the images picked up by the various types of telescopes.
  • Maybe the chills and sensations we feel that we assume are ghosts, are the interferance patterns from many blackhole wavefronts?

  • B Flat (Score:1, Funny)

    by Aspasia13 ( 700702 )
    If you were in a black hole, you'd B Flat too!
  • Or . . . . Infrastatement?

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