Gravity waves detected for the first time ever

Discussion in 'Physics & Math' started by Plazma Inferno!, Jan 12, 2016.

  1. danshawen Valued Senior Member

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    3,951
    That's too far away to observe optically, even if such an event emitted EM. So, how was it that LIGO managed to rule out seismic disturbances (like another North Korean underground nuclear test, for example) as the cause of both events? The speed of light can circle the Earth seven times in a second, and a number for the delay between the two LIGO installations was provided. Another hint, something may not have been synchronized.

    The television news program I was watching last night in Pizza Hut, as well as several internet sources I consulted when I got home all mentioned the Hulse Taylor pulsar.

    There would be no way that the pair of LIGO instruments in Loisianna and Washington State would be separated sufficiently in order to triangulate a position as distant as a billion light years. Your sources of information are, unfortunately, as flawed as this experiment, rpenner.

    If there was no optical confirmation, that is already a problem. And it isn't as if we haven't been down this well worn road before. Another fiasco like bicep2, OPERA, or the Penrose rings may have just happened. In this case, I would be happier to be wrong.

    Doesn't the uncertainty principle come into play at all for measuring distances on the order of "thousands of times smaller than a proton? " How cold / small are those interferometer mirrors? I am familiar with the most recent upgrades. It should not have worked the way they claimed it did. This was a very new and unproven / UNCALIBRATED technology, and we already know they were desperate. Would you trust a new speed camera or police laser that had never been calibrated before it was used to clock the velocity of your vehicle sufficiently to pay a large fine without question? (A fine as large as the cost of operating LIGO for several decades, for example). Me either.

    Ignored members take careful notes. This is what actual skepticism looks like. I'm not attacking rpenner. I already know, he could teach all of us here a thing or three about skepticism.

    Liked the McLaughlin impression, rpenner.
     
    Last edited: Feb 12, 2016
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  3. danshawen Valued Senior Member

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    3,951
    The supporting details about the masses of the merging black holes completed the illusion that the GW "chirp" was something observed other than acoustically. They were evidently derived by means of computer simulation. It isn't clear whether the simulations were done before, after the event or both, but according to Krauss, a means for calibrating the system was somehow arrived at beforehand, and a means of introducing "TEST SIGNALS" was also implemented.

    So, this signal was only "heard" by both installations, not visually corroborated.

    And if the system could have detected gravity waves IN AN ACOUSTIC MODE, it most certainly would have registered the recent test of a North Korean underground H-bomb test. Did it? Or if it did not, why not?
     
    Last edited: Feb 12, 2016
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  5. origin Heading towards oblivion Valued Senior Member

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    11,888
    Seismic waves travel at the speed of sound so it is very easy to rule them out. LIGO picked many false signals over the years such as trees being felled in Lousiana by loggers. The 5 sigma agreement pretty much rules out your skepticism.
     
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  7. origin Heading towards oblivion Valued Senior Member

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    11,888
    Not sure what you are talking about. My reading of the finding indicates that the detection was done with inferometers so they were in fact seen.
     
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  8. danshawen Valued Senior Member

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    3,951
    In a manner of speaking. These devices have no preferred direction, so only delays in different parts of the signal, and their relative amplitudes are actually detected. Like sonar.

    I didn't know about the logging, but obviously this would affect only one of the facilities. So neither of them are totally acoustically isolated. Then bolides and solar mass ejections (all sizes) aren't completely ruled out either. Note that it took since last September to decide whether they had detected anything at all.

    If this had been an actual bet, I wouldn't be poorer today.
     
    Last edited: Feb 12, 2016
  9. Fednis48 Registered Senior Member

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    725
    danshawen's weird skepticism notwithstanding, this is extremely cool! Between this and the Higgs boson, it's an exciting (and vindicating) time for super-delicate mega experiments.
     
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  10. danshawen Valued Senior Member

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    3,951
    FYI, I have been associated with the use of geophones deployed by a government contractor for the purpose of monitoring compliance with the terms of nuclear test ban treaties, as well as an acoustic engineer.

    Computer simulations of what you would expect to see is fine, but they can hardly be characterized as incontrovertible proof that you have detected something that you fully expected to see before it occurred. It would probably not hold up as evidence in court.

    It is also amusing to compare the dynamics of what supposedly happened for real last September with the effects of a gravity wave as depicted in the movie Interstellar, another consulting project of Thorne's. Why was it so different, in terms of magnitude?
     
    Last edited: Feb 12, 2016
  11. origin Heading towards oblivion Valued Senior Member

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    11,888
    For a minute there I thought you were going to admit that you were wrong based on the obviously convincing evidence that the rest of the scientific community embraced, but nope, you continue to move to the fringe. (you like this)
     
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  12. danshawen Valued Senior Member

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    3,951
    This detection of gravity waves has not exactly been "embraced" by the rest of the scientific community as yet, as far as I can tell.

    Lawrence M. Krauss (on twitter today):

    "My earlier rumor about LIGO has been confirmed by independent sources. Stay tuned! Gravitational waves may have been discovered!! Exciting."

    Those words are usually employed whenever there is some reasonable doubt.
     
  13. origin Heading towards oblivion Valued Senior Member

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    11,888
    I don't know Dan he seems pretty sure in these twitter posts...
     
  14. PhysBang Valued Senior Member

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    2,422
  15. origin Heading towards oblivion Valued Senior Member

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    11,888
    It would certainly seem so, his post now appears to be rather disingenuous.
     
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  16. rpenner Fully Wired Valued Senior Member

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    4,833
    In addition to the main LIGO paper in PRL, there's a flood of related papers in the references.

    Other LIGO publications referenced in the above.
    https://dcc.ligo.org/LIGO-P1500213/public/main (comparing event GW150914 to General Relativity)
    https://dcc.ligo.org/LIGO-P1500217/public/main (how often do pairs of black holes merge?)
    https://dcc.ligo.org/LIGO-P1500218/public/main (more details of analysis)
    https://dcc.ligo.org/LIGO-P1500222/public/main (GW background noise and black hole mergers)
    https://dcc.ligo.org/LIGO-P1500227/public/main (coming next week, search in space for origin of signal)
    https://dcc.ligo.org/LIGO-P1500229/public/main (alternate analysis)
    https://dcc.ligo.org/LIGO-P1500237/public/main (design details of LIGO)
    https://dcc.ligo.org/LIGO-P1500238/public/main (comparing event GW150914 to noise)
    https://dcc.ligo.org/LIGO-P1500248/public/main (calibration details of LIGO)
    https://dcc.ligo.org/LIGO-P1500262/public/main (how event GW150914 demonstrates binary black holes and thoughts about how they form)
    https://dcc.ligo.org/LIGO-P1500269/public/main (statistics on search for merger of black holes)
     
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  17. Schmelzer Valued Senior Member

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    5,003
    There is nothing specific about this. All one can say is that behind this are a lot computer simulations to obtain some approximate solution for collapsing black holes, and the observations seem to fit all this. This is beyond what laymen can do, and even scientists would need to have access to powerful computers and a lot of software written for this over quite a long time.
     
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  18. rpenner Fully Wired Valued Senior Member

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    4,833
    All the locally hosted reports have been uploaded to arXiv following the press release and the PRL journal article has had references updated to point at arXiv.

    http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.061102 (open access PDF of paper available) → http://arxiv.org/abs/1602.03837

    Other LIGO publications referenced in the above.
    https://dcc.ligo.org/LIGO-P1500213/public/main (comparing event GW150914 to General Relativity) → http://arxiv.org/abs/1602.03841
    https://dcc.ligo.org/LIGO-P1500217/public/main (how often do pairs of black holes merge?) → http://arxiv.org/abs/1602.03842
    https://dcc.ligo.org/LIGO-P1500218/public/main (more details of analysis) → http://arxiv.org/abs/1602.03840
    https://dcc.ligo.org/LIGO-P1500222/public/main (GW background noise and black hole mergers) → http://arxiv.org/abs/1602.03847
    https://dcc.ligo.org/LIGO-P1500227/public/main (coming next week, search in space for origin of signal)
    https://dcc.ligo.org/LIGO-P1500229/public/main (alternate analysis) → http://arxiv.org/abs/1602.03843
    https://dcc.ligo.org/LIGO-P1500237/public/main (design details of LIGO) → http://arxiv.org/abs/1602.03838
    https://dcc.ligo.org/LIGO-P1500238/public/main (comparing event GW150914 to noise) → http://arxiv.org/abs/1602.03844
    https://dcc.ligo.org/LIGO-P1500248/public/main (calibration details of LIGO) → http://arxiv.org/abs/1602.03845
    https://dcc.ligo.org/LIGO-P1500262/public/main (how event GW150914 demonstrates binary black holes and thoughts about how they form) → http://arxiv.org/abs/1602.03846
    https://dcc.ligo.org/LIGO-P1500269/public/main (statistics on search for merger of black holes) → http://arxiv.org/abs/1602.03839
     
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  19. sweetpea Valued Senior Member

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    1,329
    Higgs boson now gravitational waves...what next?
    Just to think, these black holes were moving at half light speed when they collided, think of the energy density at that contact point, and you can see why this caused such a big disturbance in the existing gravitational field. ( I think I got that right).
    I have picked five out of rpenner's list, now to try and understand them.
     
    Last edited by a moderator: Feb 12, 2016
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  20. rpenner Fully Wired Valued Senior Member

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    4,833
    From http://arxiv.org/abs/1602.03837 (The PRL paper)
    That peak luminosity ( \((3.2-4.1) \times 10^{49} \, \textrm{watts}\) ) in gravitational waves is greater than the total EM luminosity of all the stars in the observable universe. The total energy was about ( \((4.5-6.3) \times 10^{47} \, \textrm{joules}\)) or about 3750-5250 times the estimated lifetime energy output of the Sun.

    https://en.wikipedia.org/wiki/Orders_of_magnitude_(power)#Greater_than_one_thousand_yottawatts
     
    Last edited: Feb 12, 2016
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  21. danshawen Valued Senior Member

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    3,951
    The analysis appears to be satisfactory. In the coming week, observatories will evidently begin submitting corroborating optical and/or radio frequency/infrared/and microwave surveys of the area of interest. We won't know until then what, if anything was found to corroborate or how long they have searched for it.

    A nice Valentine's day present.

    So, yeah. Convinced.
     
  22. Waiter_2001 Registered Senior Member

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    459
    Radio.Activity?
     
  23. brucep Valued Senior Member

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    4,098
    Those kind of numbers always astound me. Thanks for picking up the paper from the arxiv.
     

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