Very low note...

Discussion in 'After Hours Lounge (Off Topic)' started by David_Moechnig, Sep 10, 2003.

  1. David_Moechnig

    David_Moechnig Stunt Coordinator

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    http://www.msnbc.com/news/963885.asp

    I did the calculations assuming sound travels close to the speed of light in the vaccum of space and with a wavelength of 30000 light-year the frequency is 1.057(10)^-12 Hz.
     
  2. CharlesD

    CharlesD Screenwriter

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    How can sound travel in the vacuum of space?
     
  3. David_Moechnig

    David_Moechnig Stunt Coordinator

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    Good question, I hadn't thought of that.
     
  4. Malcolm R

    Malcolm R Executive Producer

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    Careful, it might be the "brown noise." (South Park reference [​IMG] )
     
  5. Andrew Testa

    Andrew Testa Second Unit

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    Here's another wire release on this.

    Sound cannot travel through vaccuum. It travels as pressure waves through the rarified gasses that surround celestial bodies, particularly the accretion disks and ejected matter from collapsed stars. The speed of sound is proportional to the density of the medium it travels through, so it travels fast through metal, and slower through air. The gas clouds of ejected matter from stars are so rarified that if you were inside the cloud it would still be almost a vaccuum (no hiding spaceships inside nebula ala Star Trek, I'm afraid). But it's not quite a vaccuum, so pressure waves can traverse the gas, although very slowly. Since the speed is so slow, almost anything moving through it is moving supersonic, which creates the shock waves that show up as colorful wisps in those photos from the Hubble Space Telescope.

    The second article mentions that the time between wave crests is 10 million years, making the frequency roughly 8e-15 Hz. How much power would you need to dump into a Linkwitz transform circuit to produce that at 100 dB? You can work in terms of Solar Power Units, at 1 SPU = 3.6 X 10^26 Watts. Show all work. [​IMG]

    Andy
     
  6. Garrett Lundy

    Garrett Lundy Producer

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    Attention SVS and Bob Carver of Sunfire. Science has discovered a new refrence level for subwoofers. Please reply with LFE equipment to match this new natural subwoofer. [​IMG]
     
  7. Andrew Testa

    Andrew Testa Second Unit

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    Jeeze I'm such a geek.

    Lugging out my handy Linkwitz transform spreadsheet, an ideal speaker with an Fs of 18 Hz and 0.707 Q will be down -614 dB at 8e-15 Hz. If its efficiency is 100 dB @ 1 W/M, and the transform has to compensate by adding 611 dB above baseline to bring us to -3 at 8e-15 Hz, then it adds a total of 1,225 dB. Doubling power is required for every 3 dB increase, and that's 408.3 doublings, or 2^407.3 W, or 4 X 10^122 Watts, Which is roughly 1 X 10^96 SPU.

    Think that one through.

    That's 1 followed by 96 0s. That many suns would be required to power that note at 100 dB. If the average galaxy contains 400 billion stars, then it would take the total output of 3 x 10^84 galaxies. If there are 1 trillion galaxies in the universe, then ~10^73 universes would be required to produce that note at 100 dB.

    If we assume that only the output of 1 million stars is available (a huge black hole), then thats 1 million SPU (3.6 X 10^32 W). Crap, it's base 2 logarithm time. So that's about 108 doublings, at 3dB each, so thats 324 dB gain. If the driver is already at -614 dB from 100, then add our 324 dB gain, and we're producing a pressure wave of only -190 dB. Since 1 dB is defined as the threshold of hearing, -109 dB is roughly an intensity 10^-10.9 times the threshold of hearing.

    So a black hole outputting 1 million suns worth of energy can produce a 8e-15 Hz note at only ~10e-10, or an intensity of one ten billionth of the threshhold of human hearing.

    BTW, the capacitor and Resistor values are:
    (in kOhms)
    R1= 0.00
    R2= 1250448.40
    R3= 1421022954636400000000.00

    (in uF)
    C1= 99225000000000000000000000.000
    C2= 0.00001
    C3= 0.0000

    Reality Check: there is likely a lower limit to the decibel scale since we eventually reach individual quanta of energy and space with which to measure pressure intensity. If you want to calculate the minimum pressure exerted by a single particle near absolute zero be my guest. I'm not masochistic enough to try and calculate that however.

    Andy
     
  8. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

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    Andy,

    That's hilarious! [​IMG]

    JKS
     
  9. Zen Butler

    Zen Butler Producer

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    I heard this story yesterday on KCRW. A Bflat 57 octaves below middle C! Barry White would have been jealous.
     
  10. Thomas Newton

    Thomas Newton Screenwriter

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  11. BrianW

    BrianW Cinematographer

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