LIGO's detection of GWR and "the VETO"

[Reality Check]

How science works includes that scientists test science!
Observation of Gravitational Waves from a Binary Black Hole Merger was published on 11 February 2016 and had a 5.1 sigma signal. The data is available and presumably scientists have been analyzing the data to see whether the signal is really that good. A year and a half later we have one pre-print from a group casting doubts on the signal.

On the time lags of the LIGO signals by Creswell,von Hausegger, Jackson, Liu, Naselsky. In short they find a correlation in the noise in the 2 detectors that matches the time lag between the signals.

Described at Was It All Just Noise? Independent Analysis Casts Doubt On LIGO's Detections where a possible flaw is that they use methods based on tutorials from the LIGO website, not the higher quality methods used by LIGO in their papers.

A Response to “On the time lags of the LIGO signals” by a member of the LIGO collaboration

There are a number of reasons why this conclusion is incorrect: 1. The frequency-domain correlations they are seeing arise from the way they do their FFT on the filtered data. We have managed to demonstrate the same effect with simulated Gaussian noise. 2. LIGO analyses use whitened data when searching for compact binary mergers such as GW150914. When repeating the analysis of Creswell et al. on whitened data these effects are completely absent. 3. Our 5-sigma significance comes from a procedure of repeatedly time-shifting the data, which is not invalidated if correlations of the type described in Creswell et al. are present.

ETA: The above blog article points out something that I did not know

We first look through all our data to look for loud events within the 10ms time-window corresponding to the light travel time between the two observatories. Then we look again. Except the second time we look we shift ALL of the data from Livingston by 0.1s. This delay is much larger than the light travel time so if we see any interesting “events” now they cannot be genuine astrophysical events, but must be some noise transient. We then repeat this process with a 0.2s delay, 0.3s delay and so on up to time delays on the order of weeks long. In this way we’ve conducted of order 10 million experiments. For the case of GW150914 the signal in the non-time shifted data was louder than any event we saw in any of the time-shifted runs—all 10 million of them.

This analysis rules out signals not travelling at the speed of light, anything else is some noise transient.

 

[SelfSim]

... ETA: The above blog article points out something that I did not know

This analysis rules out signals not travelling at the speed of light, anything else is some noise transient.

I think another implication here is that noise transients, such as 'blip' or 'chirp' transients, occurring non-simultaneously (within the c window 'lag') across both detectors, would be also be ruled out as being at play here using this technique. If the 'signatures' of either of these phenomena remained following this process, then this would be evidence of propagation at c. Where no corresponding EM evidence exists in the PEM sensor array logs, one could then perhaps deduce a celestial (GW) cause. If such evidence did appear in the corresponding PEM sensor array logs however, then one couldn't deduce celestial GW type causal mechanisms (eg: a BH-BH merger).

As it turns out, there was no corresponding simultaneous PEM log data, so celestial GW causal mechanisms thus account for what remains in the combined site h(t) data.

Harry's refutation of the Creswell etal paper also rules out Fourier data transformation parasitic causes and thereby, Creswell's implied systemic causes as well.

Three classical signal processing techniques for detecting a noise embedded signal are all mathematically closely related (convolution, cross-correlation and autocorrelation). There are subtleties about applying each of these techniques pertaining to what one assumes to be 'a signal' and what one assumes to be 'noise'. Along these lines, (& IMO), the Ian Harry response you quote, appears to be consistent with LIGO's aim of doing their absolute best in minimising assumptions about what might constitute 'noise' (and 'signal'), thereby allowing the data itself, (combined with the math of the autocorrelation process), to make this distinction apparent.

I think the LIGO team has done an excellent job in their analysis, which is being demonstrated by its robustness whilst enduring quite 'gritty' legitimate scientific scrutiny. Great to see the process in action, I must say.

 

[jonesdave116]

.......which is being demonstrated by its robustness whilst enduring quite 'gritty' legitimate scientific scrutiny.

Are you saying that Mozina isn't a legitimate scientist? Strewth, never would have figured that one out on my own!

 

[SelfSim]

Are you saying that Mozina isn't a legitimate scientist? Strewth, never would have figured that one out on my own!

Well you're right in that its clearly pretty hard to find 'gritty' legitimate scientific scrutiny in the few places left where he can still hang out. (Eg, the only mainstream poster over at TBolts addressing his LIGO nonsense, looks like he's facing summary-execution-by-moderator, following an unjustified moderator attack, when that poster was also simply stating the obvious (as you are above) .. Oh well, I suppose that poster will be in the good company of those who have also gone that way at Tbolts before ..)

My last post was fairly generally directed at his latest shoot-from-the-hip nonsensical argument about GWs being indistinguishable from glitches .. (thereby providing him with evidence to falsify his "I'm a victim of mainstream ad-homs" routine). The hilarity is, of course, that the argument is singularly his alone, so attacking it, is apparently inseparable from attacking its owner (in the mind of said owner).

Anyway, I'm apparently now rendered 'faceless' also .. due to some other delusion he has about my somewhat altruistic efforts 'blowing up' in my face, whilst I was attempting to help him re-orient his wayward misconceptions about the correct physical interpretation of the sigma figure.

 

[SelfSim]

So, just a self-check, an invitation is extended to interested IS folk on what I claimed in my previous post was 'a correct physical interpretation' of the LIGO sigma figure. I have elaborated more on this in this post.

To simplify the concept of LIGO's sigma, a coin toss analogy was used (post here)

Mr Mozina's take, (and the corresponding rebuttal to it which actually took the form of a mathematical refutation) is here. Mozina then decided to conflate the two general variables in the standard sigma formula, which led to total gibberish, as was pointed out by a scientifically very well versed and knowledgeable poster, 'sjastro' here and again here.

If any of my reasoning presented in the links above, is in any way incorrect, I will be happy to retract any claims I have made, and make appropriate amends with Mozina. Please feel free critque, if interested.

I make this post here at IS, because the physical misinterpretation of LIGO's sigma figure is being used to leverage an ideologically based, anti-science methodological criticism across several web-forums and has been designed to undermine the integrity of the entire LIGO consortium.

Comments/feedback are welcome.