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Thread: Gravitational Wave Rumors Rumble Social Media

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    Gravitational Wave Rumors Rumble Social Media

    Discovery: Gravitational Wave Rumors Rumble Social Media

    In a tweet by Lawrence Krauss this morning, the well-known Arizona State University theoretical physicist and cosmologist wrote: “My earlier rumor about LIGO has been confirmed by independent sources. Stay tuned! Gravitational waves may have been discovered!! Exciting.”
    These waves are a roller coaster ride.
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    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

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    We should wait till there is a result before discussing it in detail. I would like for there to be a result, but I think it is likely it will be barely distinguishable from noise. The best thing about a result will be that it justifies using even more money to look with bigger/better tools.
    Forming opinions as we speak

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    Hope so. But as Tony says, don't go off the deep end believing what we want to believe. First, peer review, second, reproduciable results. For right now, wait and see.
    Last edited by John Mendenhall; 2016-Jan-12 at 07:07 PM. Reason: typo
    I'm not a hardnosed mainstreamer; I just like the observations, theories, predictions, and results to match.

    "Mainstream isn’t a faith system. It is a verified body of work that must be taken into account if you wish to add to that body of work, or if you want to change the conclusions of that body of work." - korjik

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    Wasn't it only two or three years ago that people were getting exciting over neutrino's possibly travelling faster than light... Lets remember how that turned out !
    Far away is close at hand in images of elsewhere...

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    Actually, I think this would be a lot different-- no one got that excited about the neutrinos that I know, we all pretty much expected the other shoe to drop. It was a very difficult measurement, and we had plenty of reason to doubt it was true. For gravitational waves, it's also a difficult measurement, but we have every reason to expect it is true-- due to binary pulsar data. No one was saying "if we don't detect superluminal neutrinos soon, we are badly mixed up about something"-- but that's just the situation with gravitational waves. We'd like to detect them, to show that physics works, but we'd also like to not detect them-- to show that there's more to know! So in a way, it's almost too much to hope that LIGO won't detect them.

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    Hm, yes, good point, KenG.

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    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

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    Even APOD is getting in on the act. The website shows a placeholder image until the LIGO presser at 11:00 EST. (Which means my post essentially self-destructs then.)

    http://apod.nasa.gov/apod/astropix.html

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    Well, this is sounding more and more promising. A couple more hours and we'll know. What's the link for the press conference?
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by kevin1981 View Post
    Wasn't it only two or three years ago that people were getting exciting over neutrino's possibly travelling faster than light... Lets remember how that turned out !
    Kevin1981. True, that some people were excited over that, but not all of them were..including myself. I've held steadfast that neutrinos and photons both travel at c and that both are massless, complying with the precepts of Special Relativity, and not violating it. They both have energy of E=hv...and momentum of hv/c. The issue of neutrino mass is that carried by the Particle Data Group, that any possible mass of a neutrino cannot exceeed the latest allowable limits of a few ev,...but that the possibility that they are still massless has not been ruled out yet.
    The experiments which have shown that neutrinos can flavor switch from electron-type, to muon-type, to tau-type, have all been carried out in experiments involving pathways through matter. There the eigenstates of the neutrinos can superimpose on the matter eigenstates, allowing fluctuations to occur without the neutrinos themselves being required to be massive. .....(see MSW matter oscillations...) If they are, then they violate SR traveling at c.
    As far as the gravitational waves go...the work of Guido Pizella @ Neutrino 88, Tufts University..showed that the Rome and Maryland bar gravitational-wave detectors, and the IMB, Mont Blanc, Kamiokande, and Baksan neutrino detectors were coincident @ 3.2 sigma...(Larry Suluk ,principal investigator of IMB @ talk @ MIT's Winter Course in Nuclear and Particle Physics 1991-2)...but the journals had switched to a requirement of 5 sigma...and disallowed it.) I never told him that the paper I wrote in April, 1982...predicting the coincidence of those two effects...that a change in the ambient neutrino flux would be seen in a sensitive gravimeter as a gravitational wave....and rewrote the paper which was submitted to Gravity Research Foundation, Babson College in their annual competition.
    I did tell him that the "funny" distortion of the walkways in the IMB tunnels....where they would "bump up" in the middle....was likely the slow flow of the salt dome under the pressure of the overburden, and that eventually, on a geologic scale....the roof of their allegedly stable cavern would fall in. It did so in the IMB 3 months later. There had been an article in Scientific American on Salt Tectonics.
    It was George Gamow, in his Harvard Project Physics Reader " Gravity" who said a neutrino/antineutrino pair could be a graviton....and the Z, the carrier of the neutral current can be any particle/antiparticle pair, so I coupled it to the Standard Model using Howard Georgi's article ,also in Sci. American, and made the prediction.
    Seen @ 6 major International Labs....3.2 sigma. Supernova 1987a. pete
    Last edited by trinitree88; 2016-Feb-11 at 02:37 PM. Reason: typo

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    Here's the short blurb, and here's the full press release. Confirmed, gravitational waves from a black hole merger. Cool.
    Conserve energy. Commute with the Hamiltonian.

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    Quote Originally Posted by Grey View Post
    Here's the short blurb, and here's the full press release. Confirmed, gravitational waves from a black hole merger. Cool.
    Wow! It's not a rumor anymore.
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by Grey View Post
    Here's the short blurb, and here's the full press release. Confirmed, gravitational waves from a black hole merger. Cool.
    Grey. That's cool indeed. I'll extend that confirmation to predict that a search of the neutrino detector database...IMB, SuperKamiokande, etc. will yield a 5 sigma coincidence of events with the timing of the seen BH merger. Betting a hot fudge sundae, three scoops, whip cream, and three cherries on top. pete

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    Can someone please explain how they know the signal came from 2 merging black holes and not the Sun nor Earth?

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    Quote Originally Posted by trinitree88 View Post
    Grey. That's cool indeed. I'll extend that confirmation to predict that a search of the neutrino detector database...IMB, SuperKamiokande, etc. will yield a 5 sigma coincidence of events with the timing of the seen BH merger. Betting a hot fudge sundae, three scoops, whip cream, and three cherries on top. pete
    Hmm, I think you're wrong that neutrionos have anything to do with mediating gravity, but I could also imagine that if those black holes had accretion disks, we might see some conventional particle interactions that could have produced a neutrino burst. Still, on the whole I think that's not too likely, so I'll take the bet. Should there be a time frame for it to be reported? Oh, and no cherries for me. I don't like Maraschino cherries.

    But I also think you already owe me a hot fudge sundae from here. It's been over five years, and I think that the astronomical community still doesn't know exactly what makes up the dark matter. I think most of them still expect it to be something non-baryonic, and at the very least there's certainly no consensus that it's all been somehow accounted for by normal baryonic matter, as you suggested would be the case.

    And of course, there's this one that still has seven years to go. I have a feeling that I might lose that one, because even if dark matter does turn out to be non-baryonic, it still might not be detected soon enough.
    Conserve energy. Commute with the Hamiltonian.

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    Quote Originally Posted by SRH View Post
    Can someone please explain how they know the signal came from 2 merging black holes and not the Sun nor Earth?
    These kinds of detectors are unbelievably sensitive, so there's a fair amount of noise, not just from the Sun and the Earth, but from trucks driving by. That's why they have more than one detector, separated by a large distance. They can tell by the fact that they got the same signal on both that it's not anything local, and they can tell by the delay between when it arrived at one and the other the speed and direction that the signal had to be travelling, so that let's them easily rule out anything nearby. And by looking at the form of the signal itself (it's not just a big spike, it has a particular pattern including a frequency, changes in amplitude, a specific time scale, and so on), and comparing that to predictions from general relativity, they can tell a lot about the details of the interaction that had to produce it.

    Something that would be exciting would be if this prompts building a couple more similar facilities. With more gravitational wave observatories(!) working together, we'd be able to get a pretty precise location for future events, and we could then take a look with optical and radio telescopes and see if we can see more detail.
    Conserve energy. Commute with the Hamiltonian.

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    Are there any such detectors outside of the US?

    I hate to rain on the parade here, but if there are any LIGO detectors outside of the US, should they not have waited for independent confirmation of the results outside of the US before going public?

    How many times have we had ground breaking discoveries announced, only for the claims to be retracted later because errors in the data came to light?

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    What are the implications for theoretical physics? Gravitons?

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    From the LIGO paper itself (which you can read for free at http://journals.aps.org/prl/pdf/10.1...ett.116.061102)

    Only the LIGO detectors were observing at the time of
    GW150914. The Virgo detector was being upgraded,
    and GEO 600, though not sufficiently sensitive to detect
    this event, was operating but not in observational
    mode.

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    Quote Originally Posted by Sticks View Post
    Are there any such detectors outside of the US?
    To my knowledge, none with the sensitivity of the two LIGO facilities. Virgo, in Italy (which has worked closely with LIGO in the past and expects to do so in the future) is in the process of upgrading their equipment. There are other ongoing and proposed collaborations. So there's probably no way to corroborate this specific event, but it seems likely that there will be such for future events. Detection of gravitational waves pretty much requires having multiple separated facilities coordinating together, so they actually have agreements to share data and publish jointly.


    Quote Originally Posted by Sticks View Post
    I hate to rain on the parade here, but if there are any LIGO detectors outside of the US, should they not have waited for independent confirmation of the results outside of the US before going public?

    How many times have we had ground breaking discoveries announced, only for the claims to be retracted later because errors in the data came to light?
    I think this is very different than, for example the OPERA experiment that seemed to point to superluminal neutrinos. In that case, the researchers more or less came forward and said they thought there was probably an error someplace, and were hoping the rest of the scientific community could help them track it down. I think this one looks solid.
    Conserve energy. Commute with the Hamiltonian.

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    Quote Originally Posted by gzhpcu View Post
    What are the implications for theoretical physics? Gravitons?
    Perhaps we can measure how stiff spacetime is with respect to rapid fluctuations vs the usual long term steady-state.

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    It's incredible what they've managed to deduce from just one event!

    - Full confirmation of the existence of gravitational waves
    - Existence of binary black holes
    - Strong upper limit on the mass of the Graviton
    - Black holes in a peculiar mass range - these are quite heavy for stellar mass black holes

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    Quote Originally Posted by gzhpcu View Post
    What are the implications for theoretical physics? Gravitons?
    I don't think this gives anything either way on gravitons. Gravitational waves are a purely classical prediction from general relativity. So this confirms that prediction, and adds a new constraint to any hypothetical theory of quantum gravity, but doesn't specifically provide any evidence for or against such a quantum theory.
    Conserve energy. Commute with the Hamiltonian.

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    Really amazing how Einstein continues to be right a full century later.
    “Of all the sciences cultivated by mankind, Astronomy is acknowledged to be, and undoubtedly is, the most sublime, the most interesting, and the most useful. For, by knowledge derived from this science, not only the bulk of the Earth is discovered, but our very faculties are enlarged with the grandeur of the ideas it conveys, our minds exalted above their low contracted prejudices.” - James Ferguson

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    Quote Originally Posted by Sticks View Post
    Are there any such detectors outside of the US?...
    People have mentioned Virgo, plus there is one being built in Japan that should come online in 2018, and some talk about building a new aLIGO site in India.
    Forming opinions as we speak

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    I hope they accounted for solar flare interference...

    http://www.spaceweather.com/images20...q47kpq90k0q6p2

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    That chart also matches up with the "about 4 detections" Sept 14 through January.

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    Site detection separation was 7 milleseconds, btw

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    Quote Originally Posted by Ken G View Post
    Actually, I think this would be a lot different-- no one got that excited about the neutrinos that I know, we all pretty much expected the other shoe to drop. It was a very difficult measurement, and we had plenty of reason to doubt it was true. For gravitational waves, it's also a difficult measurement, but we have every reason to expect it is true-- due to binary pulsar data. No one was saying "if we don't detect superluminal neutrinos soon, we are badly mixed up about something"-- but that's just the situation with gravitational waves. We'd like to detect them, to show that physics works, but we'd also like to not detect them-- to show that there's more to know! So in a way, it's almost too much to hope that LIGO won't detect them.
    I think part of the reason nobody got excited is that something was required for some sub-atomic decays, like neutron decay, , to satisfy conservation of momentum, which nobody wanted to give up, even at the subatomic level. It just took a long time to find it, the cost was modest relative to LIGO.
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    The one thing that puzzles me somewhat is the luminosity function of these events.

    LIGO ran for roughly a decade and detected nothing.
    ALIGO runs for, what, a week, and detects an event which according to Kip Thorne was not much below the sensitivity limit of LIGO.

    And there's rumors that they've seen more. 4 of them so far, I hear. My best guess is that this has to do with the large volume increase, the "broadening of the horizon. 10-fold increase in detector sensitivity gets you ten times deeper into the Universe, but in terms of scannable volume, the increase is a 1000-fold.
    Last edited by Don Alexander; 2016-Feb-11 at 08:19 PM.

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