8 ms·

What’s Up with LIGO?

75 points by valeg 7y ago

mehrdadn 7y ago
My jaw just dropped reading this: > According to two members of the collaboration, the Nobel-prize winning figure of LIGO’s seminal detection was “not found using analysis algorithms” but partly done “by eye” and “hand-tuned for pedagogical purposes.” To this date, the journal that published the paper has refused to comment. In the provided link: > Brown, part of the LIGO collaboration at the time, explains this as an attempt to provide a visual aid. “It was hand-tuned for pedagogical purposes.” He says he regrets that the figure wasn’t labelled to point this out.
- tobinfricke 7y ago
  I think this is referring to the figure on the cover of the issue of Science in which the detection was first reported. I think you will find that any ambiguities are resolved in one of the thirteen peer-reviewed publications on the detection available here: https://www.ligo.caltech.edu/page/detection-companion-papers https://www.ligo.caltech.edu/page/detection-companion-papers
dlphn___xyz 7y ago
“The Nobel-Prize winning figure. We don’t know exactly what it shows.” nice
antognini 7y ago
This is just a bit of idle speculation on my part as a former astronomer, but I wonder the extent to which the LIGO pipeline allows for non-zero eccentricities in the orbit. Because the signal-to-noise ratio is so low the pipeline has to find events by matching the observed data with precomputed templates. Thus in some sense you need to already know what you're looking for in order to find it. My understanding is that the LIGO team generally assumes that the orbits are perfectly circular before merger. This is normally quite a good assumption because gravitational waves will circularize the orbit, so if the orbit began with any modest eccentricity the eccentricity right before zero would be nearly zero. The interesting thing is that if the original system was not a two-body system but was a three-body system, then the influence of the third body could have driven the inner two to extremely high eccentricities (say, 0.999). Although gravitational waves would still reduce the eccentricity, there could plausibly still be a residual eccentricity of ~0.1 at merger. It's not clear to me how signals like that would match with the pre-calculated templates. Back when I was in the field (four years ago now) there was just starting to be a pretty good awareness in astronomy about the importance of three-body systems for various astronomical events, but I had the sense that that awareness hadn't yet spread to the LIGO community.
- tobinfricke 7y ago
  Matched filters are indeed necessary to get the most sensitivity. However, in addition to the matched filter searches, LIGO performs "waveform agnostic" searches that will find a signal regardless of its waveform. However, these searches are necessarily less sensitive than the matched-filter searches. No unmodeled events have yet been detected.
pdonis 7y ago
One factor that this article does not take into account is the signal correlation between detectors. LIGO only counts signals as a detection of an event if the same signal appears in multiple detectors with the appropriate time delays (indicating light speed travel time in a particular direction through the Earth). The same signal in multiple detectors rules out detector errors, and the relative timing rules out terrestrial origin: no signal of terrestrial origin will travel at anywhere close to the speed of light through the Earth (earthquake waves travel orders of magnitude slower).
- comex 7y ago
  Then why were 9 events for which alerts were sent later “downgraded because they were identified as likely of terrestrial origin”?
  - tobinfricke 7y ago
    It is always possible for a random signal to appear by coincidence in several detectors simultaneously. LIGO also gathers data from a huge number of "auxiliary channels" that monitor the local environment (seismometers, microphones, radio receivers, etc). Possible detections are heavily scrutinized by ensuring that the detectors were operating normally during the time of detection, and no local disturbances are seen in the auxiliary channels.
  - pdonis 7y ago
    Because looking at the signal correlation is not the only test that is applied. But it is a significant test that was not discussed in Hossenfelder's article.
  - throwaway2048 7y ago
    Because analyzing them takes time, and they want to inform telescopes as soon as possible so optical/EM data can be captured while the event (possibly) occurs. A false positive is a lot better than a false negative here.
- tobinfricke 7y ago
  Moreover, it is through these time delays, and knowledge of the angular "antenna pattern" of the detectors, that it is possible to localize the sky position of a gravitational wave source.
tobinfricke 7y ago
I did my PhD working on LIGO, but haven't been involved in the project for about five years. To me this article sounds like a crackpot hit-piece akin to the 9-11 deniers claiming that jet fuel can't melt steel. Most of the claims in this article have been refuted elsewhere, and I am sure current LIGO scientists will jump in here to further refute its claims. The matter of "retractions" is, for example, not a fair criticism. LIGO generates automatic low-latency notifications of potential detections in order to allow optical telescopes and other detectors to aim at the location of the potential event. Upon further analysis -- which takes time and can't be done at low latency -- many of these event notifications are downgraded. These retractions should not diminish your confidence in LIGO. Indeed, the team fine tunes the "false alarm rate" to avoid sending out too many false positives while not missing real events. The gravitational wave community is _extremely conservative_ in its scientific statements, and you can be assured that every scrutiny has gone into the analysis of detected events and the associated papers. The LIGO detections should not be considered controversial. There is 30+ years of science behind them, and the effort of thousands of professional scientists.
- mehrdadn 7y ago
  > The matter of "retractions" is, for example, not a fair criticism. LIGO generates automatic low-latency notifications of potential detections in order to allow optical telescopes and other detectors to aim at the location of the potential event. Upon further analysis -- which takes time and can't be done at low latency -- many of these event notifications are downgraded. These retractions should not diminish your confidence in LIGO. The post itself explained this... >> "The alerts must go out quickly in order for telescopes to be swung around and point at the right location in the sky." The rest of your criticism doesn't really match up with the post for me either. (See "I do not have the same concerns as were raised by the LIGO critics", etc.)
  - tobinfricke 7y ago
    Every paragraph of this blog post consists of FUD that has been debunked elsewhere. The blog post repeats all of these various sources of doubt without including the follow-up that has been done bolstering support for the LIGO results. It seems like the purpose of the blog post is to sow doubt in the LIGO results, which is not warranted. > Already in 2017, a group of physicists around Andrew Jackson in Denmark reported difficulties when they tried to reproduce the signal reconstruction of the first event. This has been solidly debunked by several independent groups. Here's the first Google result I found on the topic: https://www.quantamagazine.org/studies-rescue-ligos-gravitational-wave-signal-from-the-noise-20181213/#disqus_thread https://www.quantamagazine.org/studies-rescue-ligos-gravitat... > It further fueled the critics’ fire when Michael Brooks reported last year for New Scientist that, according to two members of the collaboration, the Nobel-prize winning figure of LIGO’s seminal detection was “not found using analysis algorithms” but partly done “by eye” and “hand-tuned for pedagogical purposes.” I'm not sure what this is about -- it sounds like some off-hand remark taken out of context -- but the numerous, extremely detailed follow-up publications, not to mention that the public data release, should clear up any ambiguities. https://www.ligo.caltech.edu/page/detection-companion-papers https://www.ligo.caltech.edu/page/detection-companion-papers > "Since April, the collaboration has issued 33 alerts for new events, but so-far no optical counterparts have been seen. " That should say that no NEW optical counterparts have been seen. GW170817 was a stunning success wherein a neutron star collision was observed by LIGO in gravitational waves and by numerous optical detectors. https://www.ligo.caltech.edu/page/press-release-gw170817 https://www.ligo.caltech.edu/page/press-release-gw170817 > The number of retractions is fairly high partly because the collaboration is still coming to grips with the upgraded detector. True. These aren't really "retractions," but low-latency event notifications that are downgraded on further analysis. > With the still lacking independent confirmation that LIGO sees events of astrophysical origin False. GW170817. > "Alexander Unzicker – author of a book called “The Higgs Fake” – contemplates whether the first event was a blind injection, ie, a fake signal. The three people on the blind injection team at the time say it wasn’t them, but Unzicker argues that given our lack of knowledge about the collaboration’s internal proceedings, there might well have been other people able to inject a signal." This is simply a conspiracy theory. Note that the author (Mr. Unzicker) claims that CERN, a completely separate experiment and group of people, was subject to the same kind of conspiracy. > And then there are the “glitches”. LIGO data is indeed very non-stationary (in the spectral sense) and contains various instrumental artifacts. A great deal of effort is put into understanding these effects.
ISL 7y ago
On the subject of glitches: There is an entire branch of the LIGO Scientific Collaboration dedicated to "Detector Characterization". The article implicitly, and incorrectly in my opinion, casts doubt upon the excellent work of a great many smart and dedicated people. At sufficient precision, every experiment will face unknown non-gaussian stochastic fluctuations. It is the single most-important job of an experimentalist to discern how to accurately assess the uncertainty in a measurement. LIGO's false-alarm-rate approach to significance estimation is data-driven and, to me, compelling. The false-alarm-rate approach uses a simple fact: any detector signals at different observatories separated by more than an Earth-light-crossing-time cannot be a gravitational wave. By placing time-shifted signals from the two (or three) detectors into the gravitational-wave analysis pipeline, one can determine the accidental-detection rate, no matter what kinds of glitches might occur. Detections and candidates are reported with such a data-driven false-alarm rate. Gravitational-wave searches, in the context of the post, are searches for transient disturbances in the detectors. Glitches are initially-unexplained transients. It is, in general, folly to believe that any instrument capable of sensing, in one second, an object's displacement by 1/20,000th of a proton diameter won't see the occasional unexplained transient. It is, as mentioned above, essential that a scientist using such an instrument credibly assesses measurement uncertainties. If you are a gravitational-wave skeptic, keep your ears open for binary-neutron-star mergers. A simultaneous bang-and-a-flash are nigh-impossible to fake. I'm a skeptical experimentalist (experimentalists are skeptical, as a species), and I've found GW170817 sufficiently-compelling so as to remove any remaining doubt that LIGO/LVC has seen gravitational waves (They almost certainly discovered the site of the R-process at the same time! What more do you want?). As neutron star observations accumulate, the case will only get more compelling. All of us are waiting for the next bang-and-a-flash, as the potential for discovery and wonder is enormous.
jl2718 7y ago
It’s a little bit ridiculous to hear that scientists are now so often acting as politicians and clergy, as in, defending their ideas as ‘proven’. A scientific theory is tautologically impossible to prove. It can only be disproven, and scientists should be trying to disprove theories rather than advocating for them.
- throwaway2048 7y ago
  There is nothing wrong with defending valid science against discredited, unsubstantiated, repeatedly debunked crap. Accepting their points as valid and not disputing them just leads to the perception there are two equally valid opinions about the topic, when one of them is fringe and makes bad arguments. We do ourselves no favors by that sort of attitude being common and accepted.
- erikpukinskis 7y ago
  Disproving requires discarding non-sensical counterarguments though. You don’t find a strong counterexemplar by believing every bad thing anyone says about the exemplar.
zyxzevn 7y ago
Possible false signals in LIGO via the detection of radio-waves. See: Ultra sensitive detection of radio waves with lasers https://www.nbi.ku.dk/english/news/news14/ultra-sensitive-detection-of-radio-waves-with-lasers/ https://www.nbi.ku.dk/english/news/news14/ultra-sensitive-de... It would be interesting to see how this method of EM-wave detection interferes with the GW-detection.
- tobinfricke 7y ago
  Radio signals could definitely interfere with LIGO, and show up with consistent time delays corresponding to some sky position. There are two defenses against this: 1. At the LIGO observatories there are numerous auxiliary sensors, including radio receivers, that are used as "vetoes" for candidate gravitational wave events. 2. For binary black hole or neutron star inspirals, the gravitational wave waveforms are well-modeled using numerical general relativity. The fact that the observed detection matches the prediction so well lends additional credibility to the detection. Regarding #2, we are of course hoping to detect something unexpected, with an unknown waveform. In those cases we'll rely on the veto channels to ensure that we have not detected contamination from a radio event.
  - zyxzevn 7y ago
    Good reply, but.. Regarding 1: In the article, they describe an antenna that is MORE sensitive than the normal antennas. So you may not be able to detect the low frequency radio-waves without a similar sensitive apparatus. Regarding 2: There is the problem that Electric signals can have high similarities with the "Chirps" that LIGO is looking for. For example: even in space, you can find all kinds of "chirps" caused by solar plasma. google "noises from space".
    - tobinfricke 7y ago
      1. I took a look at the attached article. The device they describe is an optomechanical setup specifically engineered to be very sensitive to radio waves. LIGO, by contrast, is engineered to be sensitive to gravitational waves and not radio waves. 2. This point is valid.
aaron695 7y ago
I remember when it came out there was something clear in the announcement that it was fake. It pattern matched the normal fake science cycle somehow. I could dig it up, but HN cares about things it likes to be true. Not things that are true. In this article not sure about the stupid release quickly then have to retract, since obviously it's needed for confirmations. But LIGO is clearly missing support. But more importantly no one is explaining why it's missing support. It's a big flag. We know its a true event. We know how to test for it. It's not hard to fake (aka not carefully analysing messy data, cold reading essentially)
deleted 7y ago
[deleted]
guest_198273 7y ago
LIGO is bunk. Zero optical counterparts since April. It's all noise. 170817 is no proof, LIGO was hours late. You guys are real crackpots and fringe cargo-cult fakers.
stefco_ 7y ago
I'm a LIGO Ph.D. student and this is a crackpot hit piece. I won't go through everything, but let me address this point: > But, as critics have pointed out correctly, the LIGO alert for this event came 40 minutes after NASA’s gamma-ray alert. I was there the day of, when this alert went out, and the reason for that delay was that one of our detectors had its data vetoed due to a loud glitch minutes earlier and our European counterparts, Virgo, had problems getting us their data in a timely manner. As a result of that, and the fact that we had human-in-the-loop checks for everything that went public, our first announcement was slow and poorly localized, with improved data products being released throughout the day. All of this is well-described in our publications [0] on the event and can be corroborated by any one of hundreds of scientists who know what they are talking about. [0] https://www.ligo.caltech.edu/page/detection-companion-papers https://www.ligo.caltech.edu/page/detection-companion-papers
- ISL 7y ago
  Hossenfelder is not a crackpot: https://scholar.google.com/citations?user=NaQZcyYAAAAJ https://scholar.google.com/citations?user=NaQZcyYAAAAJ
  - SiempreViernes 7y ago
    No, but these LIGO pieces do get pretty thin. I've been following her writing for a long time, and it seems that writing a book about how "naturalness" hasn't been very good for particle physics got her somewhat radicalised, having far more scepticism than what seems warranted. When BICEP2 was announced in 2014 Hossenfelder wrote "some people say this is wrong, I'll just say what it might mean" and then never returned to the topic with a full post as far my searches can tell. Now some danes wrote a paper with a pretty large technical flaw and LIGO representatives where a bit rude to a theorist asking about said paper and apparently this is a controversy good enough for at least 3 posts about how shaky the detections are...
  - stefco_ 7y ago
    She may not be a crackpot within her field of expertise, but she is writing confidently without doing background research. I stand by my characterization of this piece as being of crackpot quality, and while I trust that she is perfectly capable in her own field, I think her willingness to write such a slapdash post—a post that will be read and trusted by very many given her large platform—indicates a pretty cavalier approach to physics writing in general. As someone with a reasonably large platform, I think she has a responsibility to do more research before writing a piece like this; I can immediately tell that she didn’t talk to any one of the hundreds of people who could have addressed many of her points. Instead, she cites hearsay that has been addressed in detail. I don’t consider that to be good faith writing; it’s lazy and she doesn’t deserve praise for it, regardless of the quality of her other work.
worlov 7y ago
In the end, LIGO's fraud will hurt the credibility of physical science. This comparison with edited and cut templates is already a dirty trick. There is not much left of the results of relativistic computer simulations. The rest is a snippet (so-called "chirp"). You can never recover the original oscillation from this. Here the evidence chain is broken. The filtered out signal matches the prepared template, but the prepared template itself does not match the relativistic computer simulation.
- worlov 7y ago
  I mean the following: https://physicsprivate.blogspot.com/2019/09/manipulation-of-results-of-numerical.html https://physicsprivate.blogspot.com/2019/09/manipulation-of-...

75 points by valeg 7y ago

My jaw just dropped reading this: > According to two members of the collaboration, the Nobel-prize winning figure of LIGO’s seminal detection was “not found using analysis algorithms” but partly done “by eye” and “hand-tuned for pedagogical purposes.” To this date, the journal that published the paper has refused to comment. In the provided link: > Brown, part of the LIGO collaboration at the time, explains this as an attempt to provide a visual aid. “It was hand-tuned for pedagogical purposes.” He says he regrets that the figure wasn’t labelled to point this out.

tobinfricke 7y ago
I think this is referring to the figure on the cover of the issue of Science in which the detection was first reported. I think you will find that any ambiguities are resolved in one of the thirteen peer-reviewed publications on the detection available here: https://www.ligo.caltech.edu/page/detection-companion-papers https://www.ligo.caltech.edu/page/detection-companion-papers

dlphn___xyz 7y ago

“The Nobel-Prize winning figure. We don’t know exactly what it shows.” nice

antognini 7y ago

This is just a bit of idle speculation on my part as a former astronomer, but I wonder the extent to which the LIGO pipeline allows for non-zero eccentricities in the orbit. Because the signal-to-noise ratio is so low the pipeline has to find events by matching the observed data with precomputed templates. Thus in some sense you need to already know what you're looking for in order to find it. My understanding is that the LIGO team generally assumes that the orbits are perfectly circular before merger. This is normally quite a good assumption because gravitational waves will circularize the orbit, so if the orbit began with any modest eccentricity the eccentricity right before zero would be nearly zero. The interesting thing is that if the original system was not a two-body system but was a three-body system, then the influence of the third body could have driven the inner two to extremely high eccentricities (say, 0.999). Although gravitational waves would still reduce the eccentricity, there could plausibly still be a residual eccentricity of ~0.1 at merger. It's not clear to me how signals like that would match with the pre-calculated templates. Back when I was in the field (four years ago now) there was just starting to be a pretty good awareness in astronomy about the importance of three-body systems for various astronomical events, but I had the sense that that awareness hadn't yet spread to the LIGO community.

tobinfricke 7y ago
Matched filters are indeed necessary to get the most sensitivity. However, in addition to the matched filter searches, LIGO performs "waveform agnostic" searches that will find a signal regardless of its waveform. However, these searches are necessarily less sensitive than the matched-filter searches. No unmodeled events have yet been detected.

pdonis 7y ago

One factor that this article does not take into account is the signal correlation between detectors. LIGO only counts signals as a detection of an event if the same signal appears in multiple detectors with the appropriate time delays (indicating light speed travel time in a particular direction through the Earth). The same signal in multiple detectors rules out detector errors, and the relative timing rules out terrestrial origin: no signal of terrestrial origin will travel at anywhere close to the speed of light through the Earth (earthquake waves travel orders of magnitude slower).

comex 7y ago
Then why were 9 events for which alerts were sent later “downgraded because they were identified as likely of terrestrial origin”?
- tobinfricke 7y ago
  It is always possible for a random signal to appear by coincidence in several detectors simultaneously. LIGO also gathers data from a huge number of "auxiliary channels" that monitor the local environment (seismometers, microphones, radio receivers, etc). Possible detections are heavily scrutinized by ensuring that the detectors were operating normally during the time of detection, and no local disturbances are seen in the auxiliary channels.
- pdonis 7y ago
  Because looking at the signal correlation is not the only test that is applied. But it is a significant test that was not discussed in Hossenfelder's article.
- throwaway2048 7y ago
  Because analyzing them takes time, and they want to inform telescopes as soon as possible so optical/EM data can be captured while the event (possibly) occurs. A false positive is a lot better than a false negative here.
tobinfricke 7y ago
Moreover, it is through these time delays, and knowledge of the angular "antenna pattern" of the detectors, that it is possible to localize the sky position of a gravitational wave source.

tobinfricke 7y ago

I did my PhD working on LIGO, but haven't been involved in the project for about five years. To me this article sounds like a crackpot hit-piece akin to the 9-11 deniers claiming that jet fuel can't melt steel. Most of the claims in this article have been refuted elsewhere, and I am sure current LIGO scientists will jump in here to further refute its claims. The matter of "retractions" is, for example, not a fair criticism. LIGO generates automatic low-latency notifications of potential detections in order to allow optical telescopes and other detectors to aim at the location of the potential event. Upon further analysis -- which takes time and can't be done at low latency -- many of these event notifications are downgraded. These retractions should not diminish your confidence in LIGO. Indeed, the team fine tunes the "false alarm rate" to avoid sending out too many false positives while not missing real events. The gravitational wave community is _extremely conservative_ in its scientific statements, and you can be assured that every scrutiny has gone into the analysis of detected events and the associated papers. The LIGO detections should not be considered controversial. There is 30+ years of science behind them, and the effort of thousands of professional scientists.

mehrdadn 7y ago
> The matter of "retractions" is, for example, not a fair criticism. LIGO generates automatic low-latency notifications of potential detections in order to allow optical telescopes and other detectors to aim at the location of the potential event. Upon further analysis -- which takes time and can't be done at low latency -- many of these event notifications are downgraded. These retractions should not diminish your confidence in LIGO. The post itself explained this... >> "The alerts must go out quickly in order for telescopes to be swung around and point at the right location in the sky." The rest of your criticism doesn't really match up with the post for me either. (See "I do not have the same concerns as were raised by the LIGO critics", etc.)
- tobinfricke 7y ago
  Every paragraph of this blog post consists of FUD that has been debunked elsewhere. The blog post repeats all of these various sources of doubt without including the follow-up that has been done bolstering support for the LIGO results. It seems like the purpose of the blog post is to sow doubt in the LIGO results, which is not warranted. > Already in 2017, a group of physicists around Andrew Jackson in Denmark reported difficulties when they tried to reproduce the signal reconstruction of the first event. This has been solidly debunked by several independent groups. Here's the first Google result I found on the topic: https://www.quantamagazine.org/studies-rescue-ligos-gravitational-wave-signal-from-the-noise-20181213/#disqus_thread https://www.quantamagazine.org/studies-rescue-ligos-gravitat... > It further fueled the critics’ fire when Michael Brooks reported last year for New Scientist that, according to two members of the collaboration, the Nobel-prize winning figure of LIGO’s seminal detection was “not found using analysis algorithms” but partly done “by eye” and “hand-tuned for pedagogical purposes.” I'm not sure what this is about -- it sounds like some off-hand remark taken out of context -- but the numerous, extremely detailed follow-up publications, not to mention that the public data release, should clear up any ambiguities. https://www.ligo.caltech.edu/page/detection-companion-papers https://www.ligo.caltech.edu/page/detection-companion-papers > "Since April, the collaboration has issued 33 alerts for new events, but so-far no optical counterparts have been seen. " That should say that no NEW optical counterparts have been seen. GW170817 was a stunning success wherein a neutron star collision was observed by LIGO in gravitational waves and by numerous optical detectors. https://www.ligo.caltech.edu/page/press-release-gw170817 https://www.ligo.caltech.edu/page/press-release-gw170817 > The number of retractions is fairly high partly because the collaboration is still coming to grips with the upgraded detector. True. These aren't really "retractions," but low-latency event notifications that are downgraded on further analysis. > With the still lacking independent confirmation that LIGO sees events of astrophysical origin False. GW170817. > "Alexander Unzicker – author of a book called “The Higgs Fake” – contemplates whether the first event was a blind injection, ie, a fake signal. The three people on the blind injection team at the time say it wasn’t them, but Unzicker argues that given our lack of knowledge about the collaboration’s internal proceedings, there might well have been other people able to inject a signal." This is simply a conspiracy theory. Note that the author (Mr. Unzicker) claims that CERN, a completely separate experiment and group of people, was subject to the same kind of conspiracy. > And then there are the “glitches”. LIGO data is indeed very non-stationary (in the spectral sense) and contains various instrumental artifacts. A great deal of effort is put into understanding these effects.

ISL 7y ago

On the subject of glitches: There is an entire branch of the LIGO Scientific Collaboration dedicated to "Detector Characterization". The article implicitly, and incorrectly in my opinion, casts doubt upon the excellent work of a great many smart and dedicated people. At sufficient precision, every experiment will face unknown non-gaussian stochastic fluctuations. It is the single most-important job of an experimentalist to discern how to accurately assess the uncertainty in a measurement. LIGO's false-alarm-rate approach to significance estimation is data-driven and, to me, compelling. The false-alarm-rate approach uses a simple fact: any detector signals at different observatories separated by more than an Earth-light-crossing-time cannot be a gravitational wave. By placing time-shifted signals from the two (or three) detectors into the gravitational-wave analysis pipeline, one can determine the accidental-detection rate, no matter what kinds of glitches might occur. Detections and candidates are reported with such a data-driven false-alarm rate. Gravitational-wave searches, in the context of the post, are searches for transient disturbances in the detectors. Glitches are initially-unexplained transients. It is, in general, folly to believe that any instrument capable of sensing, in one second, an object's displacement by 1/20,000th of a proton diameter won't see the occasional unexplained transient. It is, as mentioned above, essential that a scientist using such an instrument credibly assesses measurement uncertainties. If you are a gravitational-wave skeptic, keep your ears open for binary-neutron-star mergers. A simultaneous bang-and-a-flash are nigh-impossible to fake. I'm a skeptical experimentalist (experimentalists are skeptical, as a species), and I've found GW170817 sufficiently-compelling so as to remove any remaining doubt that LIGO/LVC has seen gravitational waves (They almost certainly discovered the site of the R-process at the same time! What more do you want?). As neutron star observations accumulate, the case will only get more compelling. All of us are waiting for the next bang-and-a-flash, as the potential for discovery and wonder is enormous.

jl2718 7y ago

It’s a little bit ridiculous to hear that scientists are now so often acting as politicians and clergy, as in, defending their ideas as ‘proven’. A scientific theory is tautologically impossible to prove. It can only be disproven, and scientists should be trying to disprove theories rather than advocating for them.

throwaway2048 7y ago
There is nothing wrong with defending valid science against discredited, unsubstantiated, repeatedly debunked crap. Accepting their points as valid and not disputing them just leads to the perception there are two equally valid opinions about the topic, when one of them is fringe and makes bad arguments. We do ourselves no favors by that sort of attitude being common and accepted.
erikpukinskis 7y ago
Disproving requires discarding non-sensical counterarguments though. You don’t find a strong counterexemplar by believing every bad thing anyone says about the exemplar.

zyxzevn 7y ago

Possible false signals in LIGO via the detection of radio-waves. See: Ultra sensitive detection of radio waves with lasers https://www.nbi.ku.dk/english/news/news14/ultra-sensitive-detection-of-radio-waves-with-lasers/ https://www.nbi.ku.dk/english/news/news14/ultra-sensitive-de... It would be interesting to see how this method of EM-wave detection interferes with the GW-detection.

tobinfricke 7y ago
Radio signals could definitely interfere with LIGO, and show up with consistent time delays corresponding to some sky position. There are two defenses against this: 1. At the LIGO observatories there are numerous auxiliary sensors, including radio receivers, that are used as "vetoes" for candidate gravitational wave events. 2. For binary black hole or neutron star inspirals, the gravitational wave waveforms are well-modeled using numerical general relativity. The fact that the observed detection matches the prediction so well lends additional credibility to the detection. Regarding #2, we are of course hoping to detect something unexpected, with an unknown waveform. In those cases we'll rely on the veto channels to ensure that we have not detected contamination from a radio event.
- zyxzevn 7y ago
  Good reply, but.. Regarding 1: In the article, they describe an antenna that is MORE sensitive than the normal antennas. So you may not be able to detect the low frequency radio-waves without a similar sensitive apparatus. Regarding 2: There is the problem that Electric signals can have high similarities with the "Chirps" that LIGO is looking for. For example: even in space, you can find all kinds of "chirps" caused by solar plasma. google "noises from space".
  - tobinfricke 7y ago
    1. I took a look at the attached article. The device they describe is an optomechanical setup specifically engineered to be very sensitive to radio waves. LIGO, by contrast, is engineered to be sensitive to gravitational waves and not radio waves. 2. This point is valid.

aaron695 7y ago

I remember when it came out there was something clear in the announcement that it was fake. It pattern matched the normal fake science cycle somehow. I could dig it up, but HN cares about things it likes to be true. Not things that are true. In this article not sure about the stupid release quickly then have to retract, since obviously it's needed for confirmations. But LIGO is clearly missing support. But more importantly no one is explaining why it's missing support. It's a big flag. We know its a true event. We know how to test for it. It's not hard to fake (aka not carefully analysing messy data, cold reading essentially)

deleted 7y ago

[deleted]

guest_198273 7y ago

LIGO is bunk. Zero optical counterparts since April. It's all noise. 170817 is no proof, LIGO was hours late. You guys are real crackpots and fringe cargo-cult fakers.

stefco_ 7y ago

I'm a LIGO Ph.D. student and this is a crackpot hit piece. I won't go through everything, but let me address this point: > But, as critics have pointed out correctly, the LIGO alert for this event came 40 minutes after NASA’s gamma-ray alert. I was there the day of, when this alert went out, and the reason for that delay was that one of our detectors had its data vetoed due to a loud glitch minutes earlier and our European counterparts, Virgo, had problems getting us their data in a timely manner. As a result of that, and the fact that we had human-in-the-loop checks for everything that went public, our first announcement was slow and poorly localized, with improved data products being released throughout the day. All of this is well-described in our publications [0] on the event and can be corroborated by any one of hundreds of scientists who know what they are talking about. [0] https://www.ligo.caltech.edu/page/detection-companion-papers https://www.ligo.caltech.edu/page/detection-companion-papers

ISL 7y ago
Hossenfelder is not a crackpot: https://scholar.google.com/citations?user=NaQZcyYAAAAJ https://scholar.google.com/citations?user=NaQZcyYAAAAJ
- SiempreViernes 7y ago
  No, but these LIGO pieces do get pretty thin. I've been following her writing for a long time, and it seems that writing a book about how "naturalness" hasn't been very good for particle physics got her somewhat radicalised, having far more scepticism than what seems warranted. When BICEP2 was announced in 2014 Hossenfelder wrote "some people say this is wrong, I'll just say what it might mean" and then never returned to the topic with a full post as far my searches can tell. Now some danes wrote a paper with a pretty large technical flaw and LIGO representatives where a bit rude to a theorist asking about said paper and apparently this is a controversy good enough for at least 3 posts about how shaky the detections are...
- stefco_ 7y ago
  She may not be a crackpot within her field of expertise, but she is writing confidently without doing background research. I stand by my characterization of this piece as being of crackpot quality, and while I trust that she is perfectly capable in her own field, I think her willingness to write such a slapdash post—a post that will be read and trusted by very many given her large platform—indicates a pretty cavalier approach to physics writing in general. As someone with a reasonably large platform, I think she has a responsibility to do more research before writing a piece like this; I can immediately tell that she didn’t talk to any one of the hundreds of people who could have addressed many of her points. Instead, she cites hearsay that has been addressed in detail. I don’t consider that to be good faith writing; it’s lazy and she doesn’t deserve praise for it, regardless of the quality of her other work.

worlov 7y ago

In the end, LIGO's fraud will hurt the credibility of physical science. This comparison with edited and cut templates is already a dirty trick. There is not much left of the results of relativistic computer simulations. The rest is a snippet (so-called "chirp"). You can never recover the original oscillation from this. Here the evidence chain is broken. The filtered out signal matches the prepared template, but the prepared template itself does not match the relativistic computer simulation.

worlov 7y ago
I mean the following: https://physicsprivate.blogspot.com/2019/09/manipulation-of-results-of-numerical.html https://physicsprivate.blogspot.com/2019/09/manipulation-of-...