I really liked this man. Is it really just a Michelson Interferometer on a really incredible scale? Excellent job on this video. Prof Adhikari did a FANTASTIC job as well.

Thanks to YouTubers like you and Derek, the scientists doing this kind of incredible work are able to be showcased. I think a lot of personality is cut out (more often than not) when specialists like Rana Adhikari are interviewed by cable media or documentary creators. Showing him in a casual light shows the audience that anyone can be contributing to science if they work towards it hard enough. These kind of honest interviews bring a real human element to the world of science and I'm thankful the world has people like you, Derek, and Rana. Keep being awesome! :)

I like how you said it's just a Michelson interferometer

SmarterEveryDay found you!

i dont like him

I just love how adhikari face completly iluminated once he mentioned the size of the light wave, it was like he was expecting some idiot that would not really understand what he was talking about (like he has probably have to deal with before) and was just extatic to find someone that also talks his tongue

I'd wager you're reading too much into it.

Good thing Derek is a PHD in physics

I know that feeling. When I suddenly realize that the person I'm talking to understands and has some knowledge of their own on the subject, it's super exciting. Especially when you're used to explaining a thing every. single. time.

I was going to make the same comment :)

Kudos for getting a "I wish more people would ask that question" from a leading scientist in his field. That must be the best compliment ever for a layman (sorry I don't know your physics credentials lol)

He has a PhD

@@alexbartley3610 millions of people have a profile picture with them and their partner. It’s a normal thing. And it can be considered advertising your sexual preference.

This Comment section wack

@@MS69CHRIS fr

The challenge of removing the interference was crazy. The clouds themselves had a gravitational effect. And the silica threads would resonate, causing unique spikes in the readings. Wild stuff.

Prof. Rana Adhikari is SUPER AWESOME! He's obviously an expert in this field, and he's eminently capable of explaining his passion in a way that others who don't have his knowledge can more easily understand. That's a rare talent. Sir, I hope you teach undergraduates, because you are the sort who can REACH undergraduates and enthuse them about science and physics.

I really wish this channel was around when I was younger. The way information is presented in your videos makes it much easier to conceptualize and understand. Back in High School we were sat in front of a book and told to read it. We didn't care, we had a million other things to think about besides reading a bland book. I can only hope the kids watching these kinds of videos today can see the wonder in what's happening. LIGO is an incredible feat, and I'd heard the name before, but never understood what it really was doing. Thank you!

Fully agree!

A megawatt *continuous* laser? That's a helluva beam. I toured the Petawatt laser in Austin but that thing only fires for like a trillionth of a second

It's Okay To Be Smart I love your channel

I thought he said light was discrete, duh.

I want one of those - gonna troll my cat with a 1 megawatt :D

It's Okay To Be Smart the power of the laser itself is much lower but they resonate it in a cavity to build up to 1MW

Stuff like this makes "rocket science" look extremely simple.

@@charliebingaman571 exactly. A huge chunk of the technology we use in our daily lives were accidentally discovered/invented because of these 'useless' projects, as they say.

@@charliebingaman571 Better than spending billions on war

Rocket science IS simple. Its like basic Physics. Anyone with a very basic knowledge of calculus can understand most of it. NASA is kinda lame.

Didn't understood much but mind blowing how motivated humans are to do things that would take unimaginable size and money to build instruments that could have detected these things easily.

When being hit by that laser, you cease being biology and become physics.

Damn that hits hardddd

And in the end philosophy.

@@untergehermuc You need a much bigger LASER for that transition

all biology is is physics

@@micahhunter5452 Well yeah, technically everything is physics.

This interview made me think how the science of physics is basically matter trying to understand itself.

*Biologically Organised Matter

bro, science in general is just matter trying to understand matter

@@shrooman768 That's the case mostly when discussing natural science rather than, let's say, formal science. And in natural science I'd say all branches are ultimately sourced within physics.

Consciousness.

I've watched this entire video 3 times, at month's intervals, .... and it still amazes me. Thanks to everyone involved. It's sooooo cool.

Prof Rana Adhikari is clearly a star. Here's how he felt when he learned of G-wave detection: https://youtu.be/ViMnGgn87dg Those glasses provide laser protection - the laser in that lab won't vaporize your head but it could burn your retinas.

Kissy kissy.

Veritasium Name should be pronounced as Rana Odhikari ( 'A' is pronounced in Bengali as 'O')

+Veritasium Next step will be using two slits for studying the diffraction of gravitational waves!!!

I believe the upgrade to 1MW they're implementing right now. The 1064 nm lasers have excellent stability, low noise and they are not huge - this makes them ideal for this purpose. BTW older g-wave interferometers used green lasers (that's why Rana's glasses were green).

Veritasium Hey why are you guys wearing the glasses in there? Some protection?

I always like coming back to some of your older content and looking at it with eyes that have now seen some of the fruits of this research. Would be interesting to do a follow-up on LISA and see some in depth information on how they are looking at transitioning this project to space to be able to detect even more gravitational waves.

I've always been a fan of the content you and others like you (smartereveryday, vsauce, ect.) make, but recently I've been on a binge of your content. Please never stop helping us learn new things about our world!

The human race has had a lot of fails, but the huge effort and cost we put into our pure science ventures like this one, now that I'm really proud of.

Proud of faked results?

Your intelligible visulations/representations on challenging inconsistensies in the science of contemporary physics, like this one, are SO inspiring to me! Thank you so much!! 😍

So basically… gravity waves make space-time wiggle a bit and make giant lasers get darker slower when the gravity wave passes over the laser. Did I get that right? And you need to use one very low wavelength of light so that you can even detect the wiggle because on a higher wavelength, the light won’t interfere enough for it to be detected. Gosh, I feel like I’m operating on the edge of my IQ here hahaha

opposite wavelengths destroy each other, so when one of the lightwaves stretch they get more or less different, so more or less light survives so they can detect the difference by detecting the brightness of the resulting combined laser stream… probably

​@@janmamu8721 The beam splitter actually puts the photons into a superposition (similar to the double slit experiment), and then each photon will interfere with its own waveform. Photons can't interfere with each other, only themselves.

@@Jason9637 thanks!

I love scientists who don't care to iron their shirts even for an interview .

For the way he speaked initially it appeared like he wasnt really all that thrilled by the interview, it's posible that this isnt his first interview and most people can barely understand what he is talking about so why even matter, his question about the infrared light wave lenght being bigger than the distortion caused by the gravitational wave surprised him for the best, you can see how lively he suddenly become

He is not in the demanding position so why bother .

Or those that wear whatever suits them. They’re the real scientists

@@bhavikshah1946 I just thought that. Lololol dude my dad is a brown Asian and I was gonna say this. My dad is a giant Filipino and never irons anything lol

The guy running that place knows so much about what hes doing its amazing. He found the perfect job (for him).

Well he has a phD from MIT....need anything more to say?

@@rapianopenaldo1669 haha your Name

The guy explained the most advanced technology i have ever seen in 5 minutes using baby language. I feel like i am a scientist!

Rana Adhikari is an excellent communicator. It is remarkable this achievement was completed and the results accepted by the scientific community.

I watched this five times now. In my opinion, it is one of Veritasium's best. Thanks, Derek!

I love that guy, he’s so smart but so funny and relatable. I wish more people could be like him and our father derick

These people give us hope

Scientists : "We are able to detect gravitational waves from the collision of two black holes 1.3 billion light years away" Also scientists : "For the last time, the Earth is round"

ROTFL, that was a good one :D

also some people : earth is flat

Some people are born smart, some people are born stupid. And some of them just don't care what the truth is, but prefer to spout whatever comes to their minds instead. :) There's a person for anything.

and we don't are smarter people if we just believe in them not knowing the why that earth be round

Sphere not round

It's bold to try to explain such a complex system and the mechanism behind it, but I have to admit he did a surprisingly good job

Out of all the Veritasium videos I've watched, this is my favorite. Dr. Adhikari's responses were both educational and entertaining.

Any new updates in this field? You should do another video on this! This is amazing 🤩

Lots of events are now routinely being detected. And I invite you to look at how some are now using puslars to do same thing at a galactic level.

I think it may not work for now as we must consider the direction of waves coming to us like perpendicular or parallel or other angle it will affect the shift. So keeping two arms perpendicular to each other may not help. Love your videos.

I love when Professors, Teachers, Scientists, Experts look like they're at the Beach Party enjoying, but they're knowledgeable as hell.

“A megawatt will vaporize your head instantly” Good thing they have a first aid kit.

I don't think betadine and a bandaid is going to help...

I couldn't resist laughing man, you killed it

Red sus

Theres a wonderful (read, eye-popping) CGI effect in the first series of The Expanse, where a man's head is 'disappeared' instantly in space by a hi=speed traveling chunk of debris. I was reminded of that when he described this.

Meh... I'll be impressed once they start using 1.21 gigawatts ...

Can an event be triangulated between the 2 LIGO installations or would that require more accurate measurement? The 2 installations are so close together compared to the event, is this just for knowing when something has happened and we should look around, or can it be used to give us a range of directions that the event could have occurred in so we can narrow down where to look?

I think something very important to acknowledge during explanation is that these gravitational waves are tiny *at this distance from the source*. They were not tiny near the source. They were huge at the source.

This guy is genuinely happy that finally someone is asking an intelligent question. You can tell he's used to the regular media and their stupid questions

I love the idea of science just for the sake of discovery, it reminds me that when the electron was first found it had no practical use now our world can't function without it.

At first, I thought the shirt was the gravity wave detector... All jokes aside, I really do hope we learn more about how gravity works because anti-gravity products would probably change our species forever and hopefully for the better.

Rana Adhikari is the prof whose classes you tried your hardest to register for, only to realize that it was already waitlisted at 2.7 femtoseconds. I'd kill to have this guy as a lecturer.

Lol, did a pack of bacteria waitlisted him?

OuterRem that is who designed that project, easy A scientists that went on to secure govt grants

And that is why he doesn’t lecture.

Did you just said you would kill someone? I am calling the cops

Meh.

Amazing Video on many levels! How do they dissipate the 1mw of laser energy? Do they recycle it to run a generator or heat water? Can the energy be used to partially run itself?

So, if I understood it right: While the light being inside the space when it is stretched is stretched too, new light that is entering the stretched space is actually travelling the difference in distance due to the stretching.

Yes, because the gravitational waves haven't yet stretched the new light. At least, that's what I understood.

I don't know what you understood but it is different from what i understood which makes me feel im understanding the wrong thing.

I understood that they were making the tube 'boggier' to get through... (!) and not much else... As in.. I'm not sure how that then helps them with their comparison..

Yeah, and they measure the difference in time it took the new light to travel the stretche space in reference to the time it should have taken, since the wavelenght is fixed. But i feel like i dont understand it well enough.

yes, the key being that the gravitational wavelength is VERY long, so while it passes the light goes back and forth in the detector many times.

I'm really glad you did this video.. I was reading about this the other day and I had the exact same question about environmental noise.. I asked on reddit and I kinda got snobby answers.. thanks!

Light photons also carry momentum and I would guess a large one with a megawatt of power. So I guess they also need to account for the mirror getting hit and disturbed from its position (as it is not rigidly held but hanging in silicon threads), with each set of light pulses hitting in succession

The amount of precision involved here makes JWST look like child's play. Absolutely amazing.

A professor who can explain the highly complex to the every day person like me is a treasure.

Oh you are a professor!?

The professor: 1:06

The measure of your understanding is your ability to explain it to others

I was just thinking about the Veritasium audience and our demographics. I wonder at what level does he tell his interviews to explain concepts and what level most of the viewership is comprised? I ain't no professor myself or nothing, but I pick up because I am able to understand the concept at a fundamental level. I had professors, actual professors, that failed to explain much less complex questions as well as these videos do. This channel is so great.

The reason the arms are perpendicular is that the detected wave is coming at us from a distant point source. The stretching of space-time in one arm is a different magnitude of the stretching in the other arm. The difference in the amplitude of the two light beams is the detection. It is also necessary that the 2 light beams have a single source, split down the two tubes, and observed as they return.

When they pointed out that no one within space can possibly perceive the stretching of space, one thing occurred to me. Usually when scientists describe what it would be like for a human to fall into a black hole, they say that your body would begin to stretch, until you died from it as you steadily became like a long piece of spaghetti. But if space itself is being bent due to the black hole's gravity, would you actually notice your body's own spaghettification?

The most impressive part of this project was that they were looking for something they didn’t know existed; but they found it. Einstein predicted the existence of gravitational waves but nobody really knew if they were real. Now they know.

Imagine if these detectors were on the moon. You could cover a larger distance with little disturbance.

moon is too dusty. But they are talking about doing it between satellites, in space.

Very much agree with your sentiment at 8:11, absolutely fantastic that we’re peeling back reality beyond what should even be possible it’s crazy.

Rana Adhikari looks like the scientist you have to drag out of the bar to save the world at the end of a sci-fi movie when the pencil necked number crunchers have failed

stop watching movies, they are making you dumb

Going "wubwubwubwubbrrrrrrr LETS DO THIS!" and fires the gigawatt laser at some atoms

Thats oddly specific

I haven't laughed so hard in a long time. An awesome comment!

or to save the other bar customers from slipping so hard on the floor after all the chicks went Niagara

I am missing a question regarding time component of the wave. If we are in spacetime, it should also affect time. Also a statistical analysis would be interesting, how many times a detector fires, and how many times of that they both fire.

Mind expanding info. I did not understand this measuring of gravitational waves till now. Thanks for making it simple enough for me to understand.

Concerning the methods of detecting stretches in space, I wonder whether the red-shift of light packets would shift (A) in tandem with the stretching of space, or (B) despite the stretching of space? If (B), then you might be able to measure the stretching of space over a predetermined fixed distance by shooting light from one end to the other; if there is a change in expected red shift, then space was stretched. If (A), then never mind!

My mind is blown ! I would love to know how they compensated for everything and how things were toleranced

This is one of humanity's greatest achievements. The numbers are incredible. It's almost impossible to believe that it actually worked!

First attempts where in the 1950's. Tooks decades of hard work.

Humans are amazing. We are able to detect changes to our very frame of reference *from within that frame of reference.*

That is the surprising part indeed! Good thing the interviewer asked explicitely how that works, and after a lame joke he clearly explained, well kind of clearly.

@@MisterWillow Hahaha that's so accurate! I also could understand the theory, somewhat, but the practicality is still unclear to me. Basically, I'm not enough acquainted with the field.

I can't wait til they can measure the pixels on the screen of the simulation we're part of.

@@nigglebit thing is, there aint much to understand.. an interaction so strong that had too much energy dispensed.. being it noticeable over our planet system noise. This energy flow wended up stretching spacetime in the direction it came from. simply then we measure two 90 degrees angle lengths using lasers. (called interferometer). which is able to pick on quantum distances being bended in reference to another (if one length is streched more than the other it will take the light from the laser a tiny bit more time causing it to when it comes back to interfere with the other light causing positive and negative patterns of interference seen as the final laser (getting brighter and darker) with different levels of intensity over time), which happened that we were able to measure with clarity. .

@@johnterpack3940 indeed haha that would be nice and along with that i would also like to know how the universe goes into edit mode by the creator of our simulation

I think, because of Prof. Rana Adhikari, this is my absolute Veritasium favorite.

Hi there, in a video posted by you,there was an awesome explanation of the gravity being kind of illusion and not acting as force in inertial frame of reference,and exists due to the normal force, in this video gravitational wave detection is shown, could you please clarify the scenario,sounds quiet interesting..

To me it's even more impressive that we even knew to look for them.

5:23 thank you @Veritasium for answering the question I came here for. And I love how Prof Rana Adhikari was tickled at you being the first journalist to ask interesting questions. The way you introduced him was so crazy and funny! Now I have another question, were you guys wearing sunnies to protect your eyes from possible laser leakage?

To look cool 😆 😎

Such a great video, does anybody knows if the gravitational wave repeats in time keeping “stretching and squeezing” spacetime, so they can reproduce the mesure of it? or it was like a single event that they luckily capture? Because in the graphic of frequency/time of min. 0:48 (and in the vocal example of professor Rana Adhikari haha) it seems like it has an absolute ending. I apologize for my English😅

The event that created that particular GW destroyed its source: a black hole merging starts form 2 black holes and they collide and merge. That's it. In the process, they generates as much energy as a whole galaxy in GW, which is why it can be detected. However, in the Universe, black-holes merging and other cataclysmic events are not rare, there are about 2-5 events of that kind that can be detected per year, and each improvement in sensitivity allows to detect smaller or more remote ones, so more in total.

Imagine testing your lasers and then one of them bends weirdly and it turns out that they were affected by two colliding blackholes from over a billion years ago

imagined

Now imagine how the effects would have seemed if you were up close when the black holes merged.

This guy was very charismatic and fun to listen to. I enjoyed seeing these guys interact. Fascinating video, too! Thank you.

"...the next logical step is to go from two signals to detecting all the black holes in the universe all of the time" I love that statement so much

Wait.. Wouldn’t it take infinitely long (from our observation perspective) to have a motion near the event horizon of a black hole? How come they moved so fast “even from our perspective” although time dilates indefinitely near the event horizon?

To remove uncertainty this should be built in space, it'll be more precise and it could maybe even use the light from the sun instead of from a laser so that it wouldn't be too costly. Alternatively solar power could be used to power the laser

5:17 so not only are football fields a unit of length in America, footballs is also a unit of volume.

THIS IS AMERICA

@@chromiyum6849 If it was really America, he would have used cubic hamburgers.

Unacceptable, only olympic swimmingpools is approved as an american unit of volume. Still better than british, the last few years BBC insisted on using dinosaurs as a unit for everything, and just like other british products it doesnt work.

@@pflaffik I'm sorry, but that is absolute nonsense. The British have long used unladen swallows to perform various distance/time equations and not, my good Sir, dinosaurs as you so inaccurately implied. Now then. Good DAY!

EggyRepublic - I’m surprised he didn’t use the Australian unit of volume which is Sydney Harbours of water, given his Australian roots.

When you are a PhD student watching this amazing absurdly incredible accomplishment, and realizing that your simpler, and ultimately more useless research, has dumbass problems you have no idea how to solve.

Your not working in a dedicated team of probably 10-30+ PhD students, professors and researchers. Plus tons of experience and money

You're comparing yourself to a person in a much bigger and more advantageous position. I hope you weren't discouraged by this. Keep at it! You're doing good by recognizing your inexperience, but be sure to learn and improve.

Being able to recognize this is fundamental in showing you're on the right track.

I wouldn't feel discouraged. They have gone through the same processes and feelings in their research. We're just seeing the presentation of their progress. If you saw "The Martian" it's like what Mark says at the end, "You just begin. You do the math. You solve one problem and you solve the next one, and then the next. And If you solve enough problems, you get to come home." But in this case it's "You get to make massive contributions to [your field of research]." They're just building off all the little problems they've already solved; and everyone has to start somewhere. Good luck!

I hope you don't copy like you do with comments.

So in the audio world, you can take two signals, reverse the phase of one, isolate the noise by adding them together and then subtract the noise from one of the signals to get a clean signal. Is that basically what they're doing with the two stations? Cuz thats really cool.

Yes. And if there is a slightest phase shift, they gonna immediately notice that.

I can't believe that they can actually can measure these waves. So small and yet we can still do it. It blows my mind!

What’s funny is the first detection was two black holes colliding. He didn’t mention the second detection when a neutron star collided with a black hole.

I'm really glad I found this video because I first learned about LIGO in the episode on Black holes from the show Strip the Cosmos. And I had so many questions. So I'm loving this video fir asking those questions

The host asks great questions and the professor answers very well.

dontomaso11 are you kidding?

@@panimbryk I don't know if he's joking, but I think it's safe to say you don't need to take them seriously.

Marc, I agree with you. Very well explained. Lol especially if I could somewhat understand it.

I agree with Marc as well, I might be a little racist. Lol

This scientist dude is the definition of cool. "A MEGAWATT IS LIKE... IT WOULDNT EVEN RIP YOUR HEAD OFF, IT WOULD JUST BOOM VAPORIZE IT AND IT WOULD BE JUST A SMOKING STUMP.." This is the perfect way to describe it to us.

I thoroughly enjoyed this interview with Rana. He was funny, interesting, and determined in a very loose way. But I was wondering who do you go to to order up the smoothest mirror ever created? And what the hell did they say when you go "I want a smooth mirror, but not that normal garbage you make. I need it to be the smoothest mirror ever."

How can you know the source of the gravitational wave? Even gravity at two different points on earth can be very slightly different so how can they be sure its not a gravitational affect from earths gravity affecting the instruments? Very cool subject!

When converting the gravity waves from merging black holes to audio waves, the massively destructive event sounds like an adorable little water drop.

They should have built the two systems at an angle relative to each other so they could computationally verify that the stretch of length of an arm is also transformed in each system to the same ratio as the ratio of the difference of their position with relation to each other postulates.

Thank you, Professor Adhikari, for finally answering this question that has been bugging me since high school. "What does a gravitational wave sound like?" It's now the ring-tone on my work cell. (6:12)

1:07

Seems like the next step would be to place one of those detectors in space. Preferably suspended on the dark side of the moon. This would greatly reduce interference from Earth both locally and globally.

There are projects to put them in orbit. But that will take decades. Expensive, lots of R&D, ...

This professor is cool af - "Boom, it won't even rip your head off, you're just vaporised and be just a smoking stump"

What if the gravitational wave hits both the arms at the same time? There isn't a guarantee to have it hit one arm first and being parallel to the other or is it? If that would have happened would there be at least some kind of signal?

The clip of the two merging black holes in the beginning should have had them rotating around one another a LOT faster in the end (like thousands of times per second). Not that we can 'see' that, but it has been translated to sound, so it has been 'heard'... a gradually increasing whining pitch (due to the gravity waves) until... nothing (explosion). So you could actually add the audio to the video clip...

Wouldnt a movement of the mass of the earth cause some variations at both at the same time? Wouldnt it be also good to have those light beams on the space so they are completely detached from any earth movement?

Just imagine adding a third axis arm to that and then being able to pin point gravity wave sources via triangulation?! You could start making a map of the universe as it was and is now

I'm pretty sure they do that. They have two identical machines on opposites ends of the countries.

that has been tried already using radio wave telescopes to find the "origin" point the big bang....it doesnt , didnt work...the "origin" is everywhere...all at once ..kinda like 4d overwhelms 3d..

I always wonder if a magnetic field shift, tiny earthquake, air particle, or irregularity of measuring technology caused a false result with this stuff

Really like your video! Very interesting and trigger people to think. This is the essence of the scientific tutorial and

Wow! Very nice presentation. And not only all explanations but also the lots of pictures. Thank you!!

thanks so much, indeed. The first complete explanation i met. ( and I am not interested in shirts, or ironing them). And I love the attitude of you both. And the attitude inherent of the experiment, which allows to play with the limits of the accessible. In fact, the same applies to constructive = synthetic data "analysis"

I'm a blue collar type. There must have been extremely skilled construction workers involved in building this. Glad this is happening in my lifetime.

Usually these are assembled by engineers. The construction workers may have been involved in building the actual stretch of building with wiring. The actual pipe that has all the ingenuity requires precise measurements only engineers can build

Like spacecraft (space ships, drones, etc) theres engineers who specialice in working with these massive structures that despite being kilometers Long have to be made with nanometric precision

Dr Deuteron One thing that has me scratching my head a bit is that at 2.5 miles long the curvature of the earth will cause a drop of something over 40 inches. How do they get the laser beam to bend around that? Or is the tube elevated as it goes?

@@Videot99 It should have you scratching your head because it is theory(blackholes) piled on top of theory(two blackholes) piled on top of theory(two blackholes colliding) and this place is measuring the theory. What he has really created is a scientific BS meter.

@@semperfipar1299 You might want to go and check the difference between a hypothesis and a theory and stop embarrassing yourself.

I have lived a few blocks away from that Caltech building for years and this is first time I get to see what's inside of it.

As usual fantastically interesting and very intelligent interview🙏🏼❗️

Dr. Adhikari is great, lots of humor with the science.

"Now here's something most people don't think about, which is that gravitational waves stretch space-time." That's an understatement if I ever heard one. Most people don't even think about gravitational waves OR space-time at all.

How can you ‘thumbs down’ a video like this? Amazing content, as always.

I’m always the smartest person in the room when I’m watching Veritasium alone.

Sometimes i feel like the dumbest person in the room when im watching Veritasium alone

@@floreaciprian9742 Schrödingers Intelligence 😆

​​@@floreaciprian9742 Quantum superposition says you can be both as long as there's no observator in the room

​@@floreaciprian9742 It's a 50/50 either I feel extremely dumb or very smort

level of expertise is known in how simple someone can explain a complex topic in their domain.

Rana Adhikari is my new favorite professor. He needs his own show.

great video. but I find the image of the earth squeezing quite misleading: the earth, as any rigid body, is completely untouched by the waves, since electromagnetic bonds are hugely overwhelming with respect to GW. What LIGO detects is the stretching in space between mirrors that are completely disconnected from the earth (otherwise their distance won't be impacted by GW)

Its nice what people do to go further to understand our world.