Gravity waves? Maybe not.

[xelasnave]

https://www.newscientist.com/article/mg24032022-600-exclusive-grave-doubts-over-ligos-discovery-of-gravitational-waves/

Alex

[gary]

Hi Alex,

Thanks for the post with the New Scientist article link.

That sets the cat amongst the pigeons. :)

It's good to see that "extraordinary claims require extraordinary evidence"
still holds true in the world of science today and that science continues this
process of introspection, analysis and confirmation.

It would be a great pity if the LIGO detections turned out to be noise
but better to know and prove whether something is really true rather than
hope it is true.

Let's hope for the sake of all involved that it can be resolved quickly.

[astroron]

Thanks Alex :thanx:
A very interesting read.
I look forward to the result if any that comes from this dispute.
Cheers:thumbsup:

[bojan]

Interesting...

If I remember correctly, one ot two detections were confirmed on BOTH facilities, quite far away apart, and were consistent with directions both g-waves and optical signal came from..
Anyway, this is how science works - there is constant verification of previous results, by independent teams, all the time...

[xelasnave]

It surprised me.
In any event science wins.

Alex

[DarkArts]

It's a very interesting dilemma and a well written article.

Thanks for posting.

[Shiraz]

this seems to have been around for at least 18 months without resolution.

https://www.quantamagazine.org/strange-noise-in-gravitational-wave-data-sparks-debate-20170630/

[SkyWatch]

Interesting articles thanks Alex and Ray. I see from the earlier Quanta magazine article that the Danish group wouldn't talk about possible mistakes they made in their analysis of the correlations between the two detectors, so one wonders whether there is a bit of scientific jealousy at play here too...
Time will tell. :)

[gary]

Hi Ray,

Thanks for the link to the Quanta Magazine article that provides
additional background on the debate.



So to window or not to window, that is the question. :)

As I understand it, even when one doesn't use a window function on
a FFT, if you are just considering some brief time interval then
you are effectively getting a rectangular window function anyway.

I'd speculate it is the nature of a transient - something in the time domain -
to now being analyzed in the frequency domain.

However, the nature of window functions is that they create a mathematical
convolution between themselves and the signal you are sampling.
So I know experts in signal analysis have to be careful when analysing transient
signals,. There are a gamut of window function choices with various
tradeoffs and so on from which one can choose.

Given the wealth of expertise in the world in signal analysis across
multiple disciplines in engineering and science plus the number of
mathematicians and statisticians who are steeped in the
mathematical underpinnings, in some ways it seems a surprise this
debate has dragged on for so long.

Certainly the top graph in the Quanta Magazine paper
looks more correlated with a larger SNR than the lower graph when you
just eyeball it but that falls short of the analytical rigour required.

Alas, I am no expert and my experience is limited to now and then
switching on a benchtop spectrum analyzer, twiddling the knobs and
with luck trying to separate the signal from the noise in obvious
radio signals whose strength is dozens of orders of magnitude stronger than LIGO. :lol:

I note the LIGO team have one technology they call the Fast Chirp Transform :-
https://www.advancedligo.mit.edu/fast_chirp.html

They have this patent on it :-
https://patents.google.com/patent/US6509866B2/en