Have we really measured gravitational waves?

In 2017, a Nobelprize was awarded for the direct detection of gravitational waves, as predicted by Einstein's theory of General Relativity. But really we are still no sure that the events are indeed of astrophysical origin and not misidentified noise that originates on Earth.

In this video I tell you what gravitational waves are, how to measurement (directly and indirectly), what the problem is with the existing direct detection, what's the matter with LIGO's Nobelprize winning figure, and what's with the glitches.

References:

* Better climate predictions

* Articles I have written recently about LIGO

In English

In German

* How can LIGO detect signals?

* Plot was made by eye quotes:

* List of LIGO/Virgo run 3 alerts and retractions

[benheideveld]

Rarely if ever is a dispute among physicists addressed in a video. Well done Sabine

[tyronekim]

"In science it's the evidence that counts, not opinions." Thanks for that.

[EuphoricDan]

Sabine, you're one of the best voices of the rational world. I love everything you upload.

I - a bricklayer - never had the opportunity to formally study many of the things I am highly interested in (such as physics) - so like everyone else I have to defer to experts in fields that I am not well versed in. You are consistently the best and most rational explainer of the subject matter you touch upon (mostly physics, though not always). I can't overstate how important your opinions and views are to me.

Thank you Sabine.

[arbideon]

This is why I enjoy your channel so much. You focus on the data and don’t make assumptions that others make. It’s very refreshing

[craigwall]

Now THIS is what I call a kick-ass video. Kudos for holding their feet to the fire.

[smokiedapoo]

In science, debates are settled with logic and proof, not violence or childish insults.
I like how you keep science honest by jabbing them with the sharp elbows of reality! Peer review is essential in science to prevent pseudo science!

[DiegoooTech]

Your Intellectual honesty is amazing.
Thank you soo much.

[charlesblithfield]

Dr. Hossenfelder,
I love your concise and clear communication. I also appreciate your subtle humour

[jasonrobley]

Thanks for helping to preserve respect for the scientific process, your commitment to it is obvious and admirable. I really enjoy your channel, Thanks

[roshisa]

Sabine, I guess your purpose is mainly to explain science and ignite curiosity about it. And not only that. You're showing exactly what it means to "Use the Scientific Method". Maybe there are people that are not satisfied with what you're doing but they either don't understand or don't want to accept your point. But finally - "In science it's the evidence that counts, not opinions." - very good point that has to be accepted and followed.by anyone.
Thanks for putting so much effort. It's worth it. Really.

[takashitamagawa]

Thank you, Ms. Hossenfelder, for reminding everyone of what distinguishes "good science" from "bad science". Not there there aren't shades of gray, everyone must guard against wishful thinking creeping into their methodology.

[SnaFubar_]

I live about one hour from LIGO Livingston and have intention to visit once they are open to the public again. Thank you Sabine, you have given me many new questions to think about and and ask on my visit.

[derekdwhite]

Wait, hold on. I'm not understanding why "throwing away data" seems to be a problem for you. You neglect to mention that glitches are only detected in one interferometer at a time, so their source is obviously not astrophysical. Glitches are (usually) incredibly loud, so if it was an astrophysical event, they would absolutely be detected in all interferometers near-simultaneously and at near the same strength, by virtue of the fact that the signal strength would fall off at a rate of 1/(distance from the source). By contrast, gravitational waves DO follow this pattern and are detected not only in both of LIGO's detectors, but sometimes also in Virgo's detector (their interferometer is less sensitive and as such misses some signals LIGO detects) and the source can be triangulated by the delay you mention in the time it takes light to travel, similar to the way GPS works by triangulating your position via the time it takes for a signal from a satellite to travel to your phone, to give a pretty solid estimate of both the direction and the distance of the source. These facts combined make the distinction between a glitch of terrestrial origin and a gravitational wave very clear.

[i-evi-l]

The glitch vs actual detection cycle seems pretty straightforward in all honesty. A legitimate signal would be a close to simultaneous, 1sec>=, 1 signal that resonates with both detectors with the same pattern interference. If the resonance doesn't register with both detectors then it is an anomaly or a glitch. The patterns of the glitches may be interesting but hardly of note if they are not paired together by both detectors, as the detectors are designed as a pair to sort out the vibration noise that would happen in their respective localities with geological tremors or whatsoever. The system is very simple for relegating the detection to a pretty high sigma rating because it requires detection from both receptors to be a qualified target, rather than just one detector.

[fattyz]

"Selectively throwing away data that's inconvenient." Thank you so much.

[LuisAldamiz]

Don't let them intimidate you, Sabine. Criticism, sound criticism the type you do is the foundation of science.

[stefanhennig]

You are saying things that go very much against my education, my academic training and my acquired "believes". And I do beg you to continue doing so.
You are the voice from outside the filter bubbe that every sensible human and every scientist even more should be listening to.
Thank you very much for being the voice I am not happy to hear.
And, no, that is sincere, no irony at all.

[mahrocas]

"In science is evidence that counts, not opinion"
Thank you for this video.

[russ]

I want to thank you for this. For a very long time I have had same questions and asked them to one person giving a colloquia at the University I worked for years ago. At that time I doubted that LIGO actually worked for the reason you mentioned -namely that the spectrometer arm that contracted or wobbled due to the fluctuations in space would wobble the same way for the light in that path. I have since come to understand, as you said, that while that is true, the light doesn’t respond to the fluctuations the same way that the path change of that arm do (i am still not entirely clear on why but i accept that there will yet be an interference pattern due to that paths’ wobbling). I subscribed after watching your video on the Anthropic Principle which also addressed precisely issues i have had and for which i had difficulty convincing my friends in Physics. I think you do a great job of explaining these items and I commend you for your courage and insistence that consensus is insufficient for evidence or verity

[mountainhobo]

"This is highly inappropriate. We should not be giving out Nobel Prizes if we do not know how the predictions were fitted to the data" — Is it okay to be in love with someone for their intellectual honesty? There is so little of it left today.