Gravitational waves confirmed...

Discussion in 'General Science' started by cmartinez, Feb 11, 2016.

  1. cmartinez

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  2. nsaspook

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    A very small signal from a billion years ago. Amazing.

    Paper abstract:
    https://dcc.ligo.org/LIGO-P150914/public
     
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  3. cmartinez

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    This is huge! it's a once-in-a-lifetime scientific event. Being here to witness this part of history is exciting for me. Imagine... the Higgs boson and gravitational waves confirmed in the lapse of less than three years!
     
  4. joeyd999

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    Do they have visual/microwave/gamma wave confirmation of the event?
     
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  5. nsaspook

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    http://arxiv.org/abs/1409.2435
    It's part of the detection protocol so I'm pretty sure they have an electromagnetic follow-up
     
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  6. alfacliff

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    the real big thing about it is how much information they got from such a small amount of data. for something that happened 1.3 billion years ago, they can now determine how massive those two black holes were before they hit, and how fast they were traveling. since nobody was looking at that area of the southern sky when the wave got here last september, the actual lcation is not very well known.
     
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  7. joeyd999

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    In fact, they somehow computed each (which are different) to within around 1 solar mass. I find this fishy.
     
  8. nsaspook

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    They are using the same techniques used with radio, sonar and radar arrays for ages for target detection, range , size and analysis. Gravitational waves travel at c much like electromagnetic waves so once you have a high fidelity signal that matches the known constraints of the target signature it's possible to reconstruct that event with good statistical confidence.
     
  9. KL7AJ

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    It's hard to find many science experiments in recent years with BETTER corroboration. This is science at its best.
     
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  10. Wendy

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    If they could get a few more detectors they can even cut the S/N ratio way down, increasing the sensitivity significantly.
     
  11. KL7AJ

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    This is certainly true...however just those two signals are amazingly clean. I would have expected a LOT more "fuzz." :)
     
  12. KL7AJ

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    Oh, if science were this simple again! :)
     
  13. Glenn Holland

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    Pardon me for being the Skunk at the garden party, but I'm very skeptical about this "discovery".

    The science/industrial complex is a money hog and always looking for (and getting) federal funding for all sorts of obscure and fraudulent endeavors. Case in point: According to a group of scientists at the USGS in Menlo Park, claim they successfully predicted over 100 earthquakes and they want even more $$$ for a large scale earthquake prediction program.

    The Obama administration has announced a federal grant for an earthquake early warning system that will supposedly do all sorts of wonderful things like park elevators at floors, stop trains, restrict the operation of nuclear power plants and refineries. Heeeeeeellllllllllllllooooooo !!!! - This technology was successfully invented way back in 1972 and it's been fully implemented since1983.

    Goes to show you that if you pour enough $$$ into political campaign coffers, you can get a federal grant for research or to develop anything. Next thing, someone will announce a break thorough that they've invented a round thing that makes it easier for objects to move over streets and highways and it will revolutionize the future of transportation.

    Caltech is a very politically connected institution and heavily reliant on government funded research projects. If there's enough government $$$, everything will eventually be success.
     
  14. alfacliff

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    so they sent the origional signal out and therefore know the pulse width and shape of it? maybe they use the doppler? for dopler you need to know the origional frequency and the frequency shift. even the military cant tell how far radar pulses have traveled from the source, that data isnt found anywhere in the origional signal without triangulation by two recieving stations. there wasnt enough info to do that, as told by the "swomewhere in the southern sky" direction mentioned in the artical.
     
  15. nsaspook

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    You're smarter than that and know about passive detection/identification of signal sources other than by simple triangulation. The current GW detection method seems pretty close to passive sonar (Passive_sonar_signal_detection_and_classification). We have a physical model (confirmed by experimental data) using GR of how the mass and energy of the signal creating event should interact to transmit waves and how the characteristics of those waves change in time as they travel with finite speed. We have remote detectors separated by space/time to detect that wave signature as it moves across space but the detectors space/time separation is small in relationship to the wavelength of the signal so our directional capability is is poor even if our signal wave signature is exactly what we expected. We've seen the modeled (using GR) signature before with electromagnetic signals so would it have been a real shocker if the gravitational wave signature (also modeled with GR) was missing.
     
    Last edited: Feb 12, 2016
  16. alfacliff

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    passive sonar uses the time difference of incoming signals to determine info such as distance and direction. this requires more than one detector. the more detectors there are, the beter the resolution. there were only two LIGO detectors so far. barely enough to get an "over there somewhere" direction. and since triangulation over such a small baseline compared to the distance from the source is so great, not much could actually be gotten. basicly, 2.8 miliseconds delay is all they got along with the wave signature. is that enough to imply all the information on something which they only have as a theory up to now?
     
  17. nsaspook

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    That 2.8 (actually about 7 ms) milliseconds delay between detectors is very important. First you have signal wave that's not electromagnetic traveling at c (confirmed by the delay) and it allows us to detect minute differences in the phase when we see that signal change in frequency and amplitude over a short time with an energy (gravitational radiation) at almost unimaginable levels. The theory that explains this is a 100 years old so yes, we've had a while to model what that unique wave signature means in physical terms if GR is correct.
    http://arxiv.org/pdf/astro-ph/0302125.pdf
    Two merging black holes fit, all other things do not fit.
     
    Last edited: Feb 13, 2016
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  18. Monika Verma

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    Today black hole is also a mystry. Can we solve it by this detector? Its gravitational force become so high that light also can't comes out from its surface. Then where its gone. Is it no have any capacity? Or light is less thn its capacity?
     
  19. Glenn Holland

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    Black holes capture light that enters the so called "event horizon".

    They can also capture mass by the conventional process of gravitational acceleration. The captured mass then adds to the existing mass and the object supposedly remains stabile.

    My question about mass capacity is whether a black hole can reach a limit where it becomes unstable and it may disintegrate. A similar question can be asked about the original object that produced the big bang. What was there before the bang and why was it stabile up until it exploded.
     
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  20. Monika Verma

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    Its depends on the mass of star that black hole happens or not. If its mass nearly to sun than it becomes so large red giant and also unstable, and it explosed-compression. At this time its outer layer left its surface and become a ring. And immidiately its inner corecompressed and makes white dwarf.
     
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