gravitational waves detected by multiple observatories

Discussion in 'Science and Technology' started by egger, Oct 13, 2017.

  1. egger

    egger Member

    LIGO and Virgo observatories detect gravitational wave signals from black hole collision
    September 27, 2017


    "In August, detectors on two continents recorded gravitational wave signals from a pair of black holes colliding. This discovery, announced today, is the first observation of gravitational waves by three different detectors, marking a new era of greater insights and improved localization of cosmic events now available through globally networked gravitational-wave observatories.

    The collision was observed Aug. 14 at 10:30:43 a.m. Coordinated Universal Time (UTC) using the two National Science Foundation (NSF)-funded Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors located in Livingston, Louisiana, and Hanford, Washington, and the Virgo detector, funded by CNRS and INFN and located near Pisa, Italy."
    2 people like this.
  2. egger

    egger Member

    Gravitational Waves Detected from Neutron-Star Crashes: The Discovery Explained
    By Charles Q. Choi, Contributor | October 16, 2017 11:21am ET


    "There was another main clue that this new signal came from a neutron-star merger: the masses of the objects generating these gravitational waves. The frequency of gravitational waves depends on the mass of the objects that generates them — the higher the frequency, the lower the mass, Kasliwal said. The two merging objects that generated this new signal were about 1.3 and 1.5 times the mass of the sun, respectively, which is typical of neutron stars, Kasliwal said. In comparison, "the first black-hole merger that LIGO detectedinvolves black holes each about 30 times the mass of the sun," Kasliwal said.

    As powerful as this new signal was, it was also much less powerful than ones seen from black-hole mergers. This neutron-star merger converted about 0.025 times the mass of the sun into energy, "which is a stupendous amount of energy," Kasliwal said. However, the first black-hole merger LIGO detected converted three solar masses into energy, "which outshone everything we had ever seen until then," Kasliwal said."
  3. machinist

    machinist Lifetime Supporter Lifetime Supporter

    All this has been known for decades and developed into useable technologies kept under wraps.
  4. Asmodean

    Asmodean Slo motion rider

    Which technologies are you talking about, machinist?
  5. Friar Turk

    Friar Turk Well-Known Member

    It would seem that a gravitational wave (in particular, a focused or highly dense AND, simultaneously, compressed one) would have the capability of compressing space/time;shortening the distance between two relative points in space time.
    1 person likes this.
  6. machinist

    machinist Lifetime Supporter Lifetime Supporter

    Principally aerospace. Propulsion. Who knows what else it has branched off into in addition. We are talking pretty much blowing the lid off tech as we know it. We are essentially still extremely primitive. I believe, based on what I have gathered that there is usable technology developed that is to put it lightly, leaps and bounds beyond what is known. Electromagnetic theory is well over a hundred years old now. Relativity theory over a hundred years old. What we have today is childs play compared to A, what is possible, and B, what we have that is kept secret. Did you know the development of the automobile was postponed by over fifty years after the patent of the pneumatic tire because of horse and railroad industry interests? We are experiencing something similar right now.
    1 person likes this.
  7. egger

    egger Member

  8. Irminsul

    Irminsul Valkyrie

    Q: do you have any doubts
    A: there is no doubt in my mind

    Face value.
  9. egger

    egger Member

    It was explained why it is not simply face value.

    From the article:

    "A: There is no doubt in my mind. The signal is exactly what you’d expect for gravitational waves from two black holes merging in general relativity. I mean this in more than one way.

    First of all, the waveform is almost the same at both detectors (one in Hanford, WA and one in Livingston, LA). Actually’s it’s more than that. The two detectors are rotated almost 90° about the vertical relative to each other (see below). That means that the two waveforms should actually be the negatives of each other. That’s exactly what’s seen (from [1] ):

    Furthermore, the diagnostics of the detectors show that they were performing very cleanly. LIGO has literally tens of thousands of auxiliary channels: acoustic sensors, seismic sensors, radio receivers, magnetometers, monitors for the electrical grid, you name it. All of these were clean at the time of the event. None of them “vetoed” the event.

    Secondly, this gravitational wave signal is exactly the signal that everyone had been expecting to see in LIGO. Well, maybe they were expecting a binary neutron star before a binary black hole, but still, everyone was expecting to see the coalescence of a binary of compact objects. This is what theorists have been modeling for years now.

    I expected the first detection to be kind of marginal, just at the threshold of detectability. Nature was so kind to LIGO—the first thing it saw was a whopping big signal! You don’t need particularly fancy tools to detect that it’s there. In fact, with a bit of filtering, you can even just hear it out of the noise:"
  10. egger

    egger Member


    "Technically, as a physicist, I should always have some tiny doubt in my mind. Technically, it’s possible that the random noise in each detector conspired to make two waveforms with the same signal, but flipped upside down in one, within 7ms of each other. The data analysts have estimated the rate at which random noise fluctuations would make this happen: it should happen roughly once every 203,000 years (or rarer). So as a physicist, I have to admit this conspiratorial possibility. But honestly there’s no doubt in my mind."
  11. egger

    egger Member

    The recent measurement of gravitational waves of colliding neutron stars has the ability to correlate observed electromagnetic emissions of the collision with the gravitational waves, which is different than the situation of the non-emission merging of black holes which was the first discovery. It offers another layer of confirmation that gravitational waves are indeed what are being observed, not highly unlikely spurious signals.
  12. egger

    egger Member

    There is healthy skepticism but there is also denialism. Like flat-earthers, there will probably be a group of dissidents who will continue to contend that it's not really gravitational waves that are being detected but something else.

    From the 1960's through the 1990's the distance of objects generating gamma ray bursts (GRB) was debated when the evidence was not as complete and compelling that they are indeed very distance objects. One of the arguments against large distances was the lack of ability to explain how the vast amount of electromagnetic energy that was being generated by such objects. By the 2000's and later, various lines of evidence, such as the observed visible afterglow of GRB's being associated with very distant galaxies, confirmed that they are very distance objects and it became scientific consensis. There will probably be dissidents who will continue to contend that they are nearby objects using increasingly clever but flawed counter-arguments that have a probability that is orders of magnitude more unlikely than the scientific consensus explanation.
  13. egger

    egger Member

    Detection of extrasolar planets is another example. In the 80's and into the 90's there was debate as to whether periodic variations of output amplitude or position of a star that had one supposed planet were actually due to an orbiting planet or something else. After multiple planets around the same star were measured and the complex motions were exactly what was predicted by orbital mechanics derived from Newton's laws of motion, it became clear beyond any reasonable doubt that planets were orbiting other stars. It would be highly improbable for another mechanism to be producing such variations.

    On youtube there is a video giving 200 reasons why the earth is flat. Many are clever and on the surface sound convincing, especially to those who may not be well-versed in science, but all of them are flawed.

Share This Page