 Yes, thank you, and thank you very much for inviting me here. So that's my first time here. So I'm a newcomer compared to the talk you had before So I would like to tell you a little bit about What we do which is finding black holes with lasers. So I found this fantastic image But this is obviously not how we do it. Does anybody know what this? Image shows what kind of laser you see here The right laser yes, but what it is for so what's the purpose of shooting this laser into the sky here? second Nope Yeah, should have brought my astronomy 101 talk as well. So this is not what I will tell you about But this is a guide star laser You probably have heard about this so you shoot an artificial star into the sky to help an Adaptive adaptive optic system to calculate the way distortions. So this is Ordinary telescope fitting somewhere there, but it wants to have Some defined point in the sky that it knows where it is and how it looks like to calculate away distortions. So Yeah, you heard astronomy already. So my talk will be about astronomy and I think you know how astronomy looks like People getting the telescopes out and then you look at the stars. No, that's astronomy Yeah, kind of but actually If you do astronomy nowadays, it looks a little bit different. So this is just one example Again, something you heard of maybe Ska is a big Telescope project that's just been started whether UK is involved in but it will be located in South Africa and or Australia And these are just two or three or four test antennas so this will be a huge array of antennas looking like this radio telescopes so seeing Not optical in terms of normal camera waves but radio waves and making images from it but the point is they are huge machines and the actual Observer said somewhere else at a computer. So probably in the UK And that is what we call big science very much like the particle accelerators You need a lot of people a lot of machines and then you sit somewhere in a computer pressing buttons And I would like to tell you about another big machine where people said elsewhere and pressing buttons doing astronomy and Which you probably have not heard before and this is one of these This particular one is called the LIGO And that's an acronym stands for like a laser interferometer gravitational wave Observatory so the actual title of my talk should be gravitational waves so I would like to tell you about what gravitational waves are and how we detect them and Why we do this when we do this But actually I will tell this as a little bit of a personal story So a little bit how I worked in this field as a student how I work there now and what my students do so that I hope I can tell you two things at the end that this big science is a very Slow process so you can't just have everything you know invented by genius into two years And then everything is there but actually as a physics student you can have a big impact on what's happening already so it's probably The things I find the most surprising Myself, and I know that most students don't understand this before that you can have an impact, but it takes 30 years Okay, that's will be my story So let's start with gravitation waves. So most people have not heard of those things. So what are gravitation ways? The reason we want to look for them looks like this and this is how the university mostly looks like Now what I mean by that 96% of the universe is dark So we know from measurements that there are stuff out there and we can see some of its stars and some planets and so on But we know that from the energy and mass we can kind of assume in the universe to make everything look as it should look like We know that 96% of the universe is dark meaning we can't see it and the only way we typically See things is by looking with a telescope. So if it's dark, we can't see if we don't know actually what it is So that is the reason we want to try to measure something else one of these something else is is called gravitation waves and he is just a kind of Buzzword summary I usually give in a in a science seminar. So what are gravitation waves? I will explain this on in a few slides afterwards. So first of all, they are Predictions so that's a theory somebody had an idea that these things should exist And the someone was Einstein when he wrote his theory for gravity and out came gravitation waves as one of these predictions and then What is actually kind of means you try to make a picture of it and the picture we come up with it Those are ripples in space and time. The other thing is we want to do astronomy with it So what produces these ripples in space and time while heavy objects that are accelerated so you need a lot of mass and then I have to move very quickly so that could be for example black holes or other cosmological objects and Yeah, so This is all a little bit complicated. Let's try to see whether we can explain. It's a bit better So this is a photo of how we try to explain it during our outreach session and so on where the idea of Space and time or something that can stretch and that can have ripples is a little bit visualized so the the idea to understand it is To see space and time as a rubber sheet Where the curvature in this rubber sheet gives you gravity? Okay, step back a little you know gravity is usually a force so Newton's law of gravity to masses attract each other And Einstein tried to calculate that a little bit more precisely because they have some things that didn't work So planetary motions for example are not exactly following Newton's laws And there were lots of people trying to get this all together and Einstein at some point at the idea to write down these equations slightly differently the idea he had was to not have these kind of forces between masses to be instantaneous but that they were also limited by the speed of light and To write this down in a nice elegant way He had this tensor algebra and that effectively Transformed the force into a curvature of space time So the way it works if a mass you put it somewhere and it curves space time and the curvature Again attracts the next mass so gravity is curvature So mass creates curvature curvature attracts the other mass and this is how we demonstrate it So you put a heavy heavy object in the middle That forms this kind of shape So that is a gravity field and then you take a smaller mass and you roll it along and it forms an orbit automatically So you can imagine this is not distracted by gravity. It's just the shape of this rubber sheet that forms this motion So just trust me. This is so far the best theory on gravity We have and if that is right So if you have these elastic rubber sheet and you move masses and you can see this if you actually do this with this Demonstrator we have you see there ripples running through the surface So everything that is elastic and does that should have ripples and that's the same that came out of the equations of Einstein He said oops if I do this I get waves and these waves are really just changes of the Gravitational field or space and time together Okay, so let's assume these exist Where do I get those from? As I said accelerated masses. So if I make this I'm accelerating my my arm and I'm creating Gravitation waves. So everything around us all the time Generates these gravitation waves, but there's a slight problem with it that the energy that you create The gravitation wave width depends on the mass that you're accelerating and you have just two examples so there's a claw one of these big things in an amusement park in Australia and below for it in the the luminosity So that's one of these units. It's like a light bulb. You give it in watts So how much radiation is coming out of that thing and you see it's a zero with Can't remember how many many many zeros and then a one So it's a very very low energy light bulb in terms of gravitation waves when you go on the other hand to something like Two black holes that orbit around each other Then you get again a very very Many zeros, but all in front of the dot. So this is a very very high luminosity source for gravitation waves and What we can you can do the Mars and you can see that Everything we can do like with a claw or anything we move on earth is too weak for us to see But there are things out there in the galaxy In other galaxies in the universe that are very very happy. So they make these very luminous sources and that's what we We hope we can see and that's why I'm talking about astronomy because there's nothing on this planet that we can possibly see was gravitation waves That's why we have to go elsewhere But elsewhere there are quite a few sources that Normal astronomy has found already and we know they exist. So they're for example binary systems. So probably You don't know this but most of The objects in the sky like to exist as a binary so stars that you see but also kind of bigger system like to To end up in a binary form, which is kind of the natural Behavior if you throw a lot of things together that orbit each other and have a chaotic system and they kind of Organize themselves like our solar system did and in a star level a lot of these self-organization Leads to binaries and if you have binary stars And you're also expected of binary black holes and binary neutron stars and binary white dwarfs everything in double and these kind of spin around each other and at some point they orbit around each other closer and become very violent systems the other thing That you heard about a supernova which are just star explosions But of course it also means there are great masses accelerated. So we know these exist and we detect them With normal telescopes. So we expect that these would also generate Gravitation waves then there are some other things that we know exists We don't understand so so well exactly like pulsars pulsars are neutron stars that rotate very very quickly And we see them as radio blips in the radio antennas that you have shown you before But we expect them also because they rotate very quickly and not being exactly round to be accelerated masses because they rotate very quickly and generate gravitation ways and the same for creating stars where mass a lot of Stars have a companion where the mass from the companion is falling on to the other star. It's called accretion So this process should also be moving a lot of mass very quickly so there are a lot of these things we would like to know more about and Maybe gravitation wave can show us more. So this is an Simulation we then done in the computer. So I imagine you have to let's say black holes that orbit each other And you will visualize the gravitational field lines of these kind of green things and as these become closer and Spiral closer together. They start to rip each other apart and finally form one merged black hole and doing this violent process a gravitational field gets very strong and radiates away in this In these red fields. So what you get from that is effectively there is at the end of a long process some violent, you know Death spiral at the end that generates a lot of Gravitational field that radiates away and this is something we would like to we would like to see now Just another simulation that looks a little bit Further out so again these big blob is where it simulated just in the center is now something like these two black holes that That rotate around each other and the big blob is just the simulated Gravitational wave field and there's somewhere on the left as these little tiny yellow ball swimming in there That should be us somewhere far away. So this galaxy scales. So at our position on a planet somewhere else this would Hit us Later, obviously and at that time it becomes these ripple in space and time So it's really like a water wave hitting you when you're sitting somewhere else You know somebody throwing a big rock in the water here and you in a boat there After while you both slowly rocks and that's all we can see so we're not looking for something We can't make a picture of it's more like Microphone or like bobbing a cork in the water So the thing that we can see is these kind of echoes of a distortion in space and time somewhere else sounds very weird, but This is how It would look sound like in real. So if somebody asks you how gravitational wave sounds like you have to make whoop You know where they where this whoop comes from so that's one particular example There are many very very different versions, but this is the most Common one and relates to the pictures. I've shown you before Anybody an idea why the sound is like like you heard just now Well, it starts low. Well, it has this kind of Stuttering as well, but I'm talking about that is low and then it going to higher whoop You know why that is Yes, and any idea why that is You things get faster and faster. So what you hear is really the rotation period of something is spinning So this was the signal for to a neutron stars or black holes in spiraling So they start doing this lower and the the closer they get the quicker the orbit becomes and that's why the The wavelength which is just proportional to the orbital speed goes quicker. So this would be our astronomy So no pretty picture But a lot of sound So there's a whole department Everywhere for people trying to make then nice images out of sound it works similar to so now you need microphone technology Just applied to astronomy, but that's not what I would like to talk to you about There's another thing that we can do with gravitation waves And this is to help people like at the sky and telescope magazine to finally Understand whether Einstein was right or was he wrong because what we want to do is to measure a prediction of The general relativity that Einstein proposed and even though we think this is a very good theory It's a theory that means at some point it will be wrong So Newton is still right when I drop an apple here But he's wrong when I want to compute the planetary motion of Mercury So Einstein is right when I want to compute the planetary motion of Mercury But is he right if I want to compute to in spiraling black holes? We don't know we haven't done it then So that is something again where a lot of people are interested in and again That's not something I'm going to tell you more about what I want to talk to you about is The detection process so I'm an experimentalist and I'm working on the instrument So I'm building the machines for detecting these ripples in space-time on earth And that's what I would like to tell you more about So what we use to detect gravitation waves is laser interferometers and To show you how that works I have to leave this fancy presentation and show you some Little programs that my students have written to explain this a little bit better So the first thing is what does actually a gravitation wave do when it hits us But what we can actually see is that it changes the length So this is a typical example how we try to explain is these Boles there these red circles should be free free floating masses somewhere in space and then there's a gravitation wave passing through the screen like this and What it does this is would stretch and squash the length between these three masses So if you could put these somewhere in space And the gravitation wave would go through you would see something like this and as I said gravitation waves are Everywhere all the time so you can if we can get some light into the audience that works a little bit better so The gravitation waves that's coming out of the screen hitting you Would then stretch and squash you all the time a little bit the only problem is here. This effect is very Accelerated so unfortunately, this is so small that we can't see it, but it happens all the time and This is what we want to detect so if you wanted to detect something like this what you can do is measure length So what I what I wanted to show you is that these How this actually what is shown in the top row actually works in real time? So we're talking about these kind of frequencies so things are moving as you as you see them The only problem is that's very small. So what we want to see is what I call their delta L as a change in a length L so let's say if a meter Then I want to see how the meter changes when the gravitation wave happens and I have to multiply that by the amplitude of the gravitation wave Which we call H and the problem is written there H is tiny So it's 10 to the minus 22 for an optimistic Expectation so if we have one meter it would change by 10 to the minus 22 meter as anyone of you remember how large an atom typically is shout louder Minus nine no smaller 16 is good. I usually remember 15 depends on the atom. So This is a million times smaller than an atom That's what we want to measure and that's why the detection I mean the experimental building in apparatus that can see that is fascinating and complicated so the way to do this is use laser interferometry that is something we Have as a best instrument and this quite old so without the laser it was invented 1887 by somebody called Microson and this is how somebody recreated that that was done with an oil lamp Instead of a laser, but it works the same same way. So you have two interferometer arms I should probably show you that sketch again So the lower one shows in an interferometer So you have a light source on the left and then you split the light into two arms and then it comes back and overlaps again and because light is a way that can interfere with each other depending on how long the travel time along these arms were was the output which is in This way sees a bright or a dark spot. So you just look into it and it is bright or dark This changes when you change one arm length and if you change it by one wavelength It goes from bright to dark and that's what we call a fringe So you can sit there and when you see it going from bright to dark You see how the arm has changed by one wavelength which is a small number So for normal light, let's say ten to the minus seven meters So that's not quite as good as we want but it's not too bad So and then you can try to look better Then just dark bright you see kind of changes in the brightness and Microson looked there was his eye into the interferometer and tried to do that And he thought he could do this to a percent level change between dark and bright So that's what we call a percent of a fringe. Now You got a bit better Mostly because of the invention of the laser So with a laser you have a very very stable light source Where you can detect gradual changes in brightness much much better and this is a report For ready gravitation wave detector, but effectively it's the same thing So the laser is here on the right and then you have these two arms and you detect The output same method just better technology and that is 1972 just after the invention of the laser and you see the detection was much much more precise a million times better already and Since then we even got better. So we have now Again the picture of LIGO one of these big things and now you probably recognize a little bit more what this is So this is two very long tubes with a corner So this is still the L shape of the Microson interferometer and their laser beams traveling around these Tubes and what they do is measure length and precision now has even more zeros and here we finally can see length changes that are smaller than that of Of an atom and even smaller than that of a atomic nucleus So these things Exist and there's not just a LIGO Detector so LIGO even as two Remember I told you we only hear the sound like a cork bobbing on water So it's like a submarine hearing a different submarine if you want to know where that other guy is You have to have a couple of microphones and then do this triangulation exercise to see where the This sound came from and we have to do the same thing. So if we have only one antenna We we can detect it, but we don't know where it come from which for astronomy It doesn't help us very much. So we have to have a network So there there are a couple of these things of the LIGO detectors to then one in Italy will go one in Germany is called Geo There's one under construction in Japan and one planned for India and these are our ground base Also space projects, which I want to talk about. So I would like to Talk to you about these projects and show you a little bit how they evolved and where I worked on these So that you get a little bit of an insight how it is to work on A big science project and what I like about our science is it's new so particle physics We had before was at this stage 1960 Okay, so even though for you might be new that there is a large hydrogen collider They they had already big accelerators and nice results and one Nobel Prize is 40 years ago So we haven't okay, so we're just starting and you can be part of this by You know seeing this in the news by looking this up So this will be kind of the stuff that is old news in 40 years, but now it's it's pretty Fringe Science so the first generation of detectives tried to build these type of Microson just much better And there were a couple of projects So I'll give you some of these names already And the key here is the time so they were proposed in the 80s because with the laser We thought well we can maybe do it then between the proposal and actually the building You actually then get to work and try to invent the technologies You need to to actually do it then somebody gives you the money and you start building that was in the 90s And you say who I bet I work harder on the new technologies now because I really have to make it work And while you're building you're still inventing stuff to build it in and then in 2000 something we were ready and Stop working on it and switch them into science mode That means everybody hands off and just try to detect something because while you're working on them They can't see anything So that was what we call the first generation of detectors and I worked on these So I'll show you a few pictures of those to get feeling for it. So this is the German One which is actually a German British version. So half it done by German groups half of it by groups in Britain And this is where I did my PhD. So I was sitting in these containers there. So Not as fancy as you might hope Inside it looks a little bit fancy because it needs to be all clean So these are typical vacuum tanks like this guy just a bit bigger and better Because we need a vacuum for the laser beam. Otherwise the the air or gas would distort our reading and As I said, we have new technologies. So I showed just one example for the various bits and bobsicle in there So what geo pioneered at that time was the so-called mirror suspension system So when you want to measure a length change for a laser beam What you have to do is you send the laser beam and then you bounce it off a mirror So it comes back. So then the motion of this mirror is effectively what you want to see and You can imagine if you want to see it to tend to the minus 18 20 meter that mirrors to be pretty damn quiet and good And this is to make it quiet. So the mirror is these lower circle Which is the lower piece of glass in this photo and all above is the so-called suspension system And that's like in your car where you have a spring so that when you drive through pothole the shock wave doesn't Traveled to you, but is kind of suppressed by something which is oscillating the spring So we have springs up there as well, but we are also pendular so just wires But they all do the same thing if something shakes on the top the mirror doesn't shake Okay, so that's the suspension system and of course the details are quite complicated So there's a lot of development going in so that this thing is really really quiet down there and doesn't move So she say as I said what we actually then do we sit in a computer room and press buttons So that was me in 2001 and you see we were terribly understaffed I had to clone myself to be there at least four times and I Had a little bit of help from Einstein as well sometimes So that was our control room to control the interferometer in the early days So after my PhD I moved on and worked in Hittory and that detectors called Virgo Which is near Pisa and this looks a little bit more fun because the landscape is nicer and it's longer so this one is a three kilometer one and you see the buildings are a little bit bigger so they had more money to build it and One of the thing they spent the money on was again the mirrors, but in a different thing So okay, we now know how to suspend those that they're quiet But imagine we want to measure light bouncing off a surface and then how the surface moves by 10 to the minus 20 meters But even one atom peeking out is much much larger than we want to measure So you can imagine that the surface must be very very smooth and then also the quality of the material must be very pure and So this is a mirror even though it looks like a piece of glass because it's made to be reflecting only for that particular laser light That we want to bounce off for normal light. It looks like a piece of glass But we wanted to buy these things and they weren't available. So we had to pay several million euros to a glass company in Germany to make us a better glass So now it's sold by the company also to other people but at that time there was no market So they wouldn't do it otherwise and then they need the scientists help to actually understand what exactly we need So this is what what the biggest impact of Virgo was at the time So when I went there these glass pieces were just delivered and then installed and then one of the the task that I worked on Was actually you have a three kilometer long tube and it's this big and you have a laser beam And you want to shine it in so that it hits The end of the tube as well, which is actually not so easy So that took us some time and when we finally done that just tiny step in the whole process everybody was very happy So that's again me you see the most interesting thing. I didn't change my top from going to Geo to Virgo two years So that was the control room in Virgo and that's really again how to work So the laser somewhere else a mirror somewhere else But because it is also sensitive to to movement and to to noise you have to be somewhere else everything is computer controlled So we did all this work from From that control room when we had things working and then if things stop to work We went into the lab and fitted with this. This is a kind of experimentalist work have done there and then the biggest Detector in terms of the length but also because it's the most advanced one is LIGO But I will not tell you very much about this because there's the LIGO magazine, which is really Something you can download and read and find out a lot. I think that's the best thing out there at the moment to find out what's going on and I'm saying this because it's me again I'm the I'm the editor-in-chief of that magazine The way why I tell you this is that this is a typical thing you do as a scientist So I'm a researcher. I want to be in a lab. So why am I here and why do I do this? So we we kind of have various roles and we are expected to have various roles. So I'm Expected to do outreach. I'm expected to do so-called service work as well for the collaboration when you are in this Detector groups where there are thousand people working on something Everybody has to help to make it work and one of the jobs I took to do them I service is these editor-in-chief Of the magazine, so that's downloadable for free easy to Google so you can do that later and While we haven't detected anything yet Okay, that didn't work So we learned a lot in the process and we built this this huge collaboration as I said This is like Sun was in the in the 60s The main work is to get things going to get a momentum to get people on board that this is interesting and so on So we built all these detectors. We measured for ten years and we didn't see anything so what do we do of course we would another detector and that is of course bigger and better and that should then finally work and I think actually will because we learned so much we've become Now an international collaboration of the order of turn in terms of how much money is spent there How many groups are participating so this is not fringe science anymore even though it hasn't reached yet the public it is now a big science as we wanted it to be and What do we do by making it better? so we take the existing sites which were the expensive part to build all these big holes and big tubes and Replace some parts with newer parts because we understand better what we want to do and this is going on now and will Be still being looking like this until 2015 before we can again switch it on to take some data and Advanced here is a strange keyword for better But what I mean by that is we have still the idea of the Microson we throw more optics at it And this is for making a couple of noise couplings where Something is shaking and because of that our mirrors are shaking and because of that We cannot see the gravitation ways these kind of couplings lower by making the system more complicated But by understanding more we can do that now So I'll just give you one example when I The these kind of little symbol at the bottom there is showing you photo detector that looks into this fringe seeing whether it's dark or bright So I draw this there as this kind of official symbol for photo detector But when you look at this how it's looking in real, this is this table on the right Which is one by two meter and the reason why it's so complicated is because you need to detect high power beam very sensitive and you have to detect various degrees of freedom also how it moves and How the shape changes and for that you have to split it in various components and have very specialized Detectives so this is a type of advancement. We now understand who we can do so the the inside of one of these vacuum tanks looks also more like a building now so again This is something like this but people working inside of course no vacuum at that time So they work and then they go out and then you pump down But what you see there is these kind of suspension system for so these kind of shimmery thing in the middle so not the one with a green spot on it, but the one below is one of the mirrors and This is the key so one of the heart of heart component of the system that keeps the mirror quiet and We've built in Birmingham and in Glasgow here in the UK part of that system Most of the system is actually from the UK and in Birmingham. We've built just one control component For it and this is one of the famous guys. We sometimes then get into our lap so that's David Willits visiting our lap in Birmingham and You know like you he was probably surprised that it's actually students or PhD students that build this hardware that then shipped to the To the US to be installed in this multimillion dollar machine So if you're a student PhD student you would actually have your hands on your things so that's what what we've done and so then hopefully and let's say 2016 we detect the gravitation wave somebody will get invited to Stockholm or get a Nobel Prize and The astronomy will start so this for sure will be like the Higgs detection just recently So there will be a big media attention and there will be astronomy finally done, but I'm an experimentalist I built detectors so the question is what do I do then now when advanced live was finished so of course, we don't stop we go on and There are two things I want to show you quickly so the one is what's going on between now So we built all the parts they all shipped to the US What do I do? So the problem is once you install these things and a very complex machine and switch on nothing will work Because individually they work, but if you put them together they don't so there's a phase That's called commissioning where you try to make it work and just two weeks ago was that this workshop commissioning a simulation? It's a lago side where we try to understand in advance the before would try to switch it on why it will not work and Then to try to already devise some strategies how to make it work So One example what could go wrong? So long vacuum tube with a laser beam At the end of these tubes. Yes, these tanks guys like this bigger in each of these tanks You have this kind of suspension system and which there sits a mirror Okay, so actually I didn't tell you that in detail, but there's it too at the end of each arm So you you basically create a resonator between these two mirrors now. This is one of these mirrors 40 kilo-gon glass piece Very expensive very clean very flat But how flat so on the right you see here is surface measurement of that mirror So we've delivered The the company we ordered these mirrors from for LIGO have delivered and now the question is can we accept them? Do we sign the check for a couple of million dollars and say yeah, thank you or do we say no? That's not good enough So we do a lot of work on metrology where we just measure the surface and you see the scale probably not but this color scale is Plus minus 2 nanometers So the the surface is not perfectly flat, but the highest and deepest valley is just a few nanometers So the question is whether it's good enough for us or not So how do we do this? We do optical simulations where we take the measurement Put it in a computer Simulate this kind of thing where you have two mirrors and then what I've done here So what you see as a video is a simulation where just move one of the mirrors And then you see various kind of shapes appearing what we want to have is this kind of bright round shape Which is the usual laser beam and the other shapes are created by these distortions and by using the simulation we can Kind of anticipate what we will see in the experiment and first of all just make the make the conclusion Is this good enough or not? So this work was done last week by one of my students in and the LIGO site again PhD student making the decision Whether we accept these several million dollar Mirrors or not and what we used for that and that's another funny story is the simulation I've wrote as a fun project when I was a PhD student So that was something I was not supposed to do but I was Kind of liking programming even though I was an experimentalist so I did this on the side because I wanted to play with optics in the computer and this is still used so This is on this website as an open source project It's not somewhere secretly hidden for this big project. It's something you can download and play with it and Again, it shows you how Close you can get to big projects easily and just to give you an example for the real life So we do the simulation so that we Know what the interferometer will do to us so that it smiles at us rather than laughs at us So this is actually a reflected laser beam that should look like a normal round spot but because of the surface defection it has strange shapes and this was one of them the first Cavities that was installed in advanced LIGO at these kind of shape looking back at us Okay, so the other thing I wanted to show you is another thing I work on which is called optical design Which is a little bit less experimental where we just sit down and try to understand Okay, what we've done with LIGO advanced LIGO. Can we do this still better? And we would like to do something in Europe and that's what we called Einstein Telescope The idea is to be again bigger and better and go on the ground again a little bit like so and we go underground because it's more quiet So this idea is that you have a triangular shape with several detectors underground as a facility Like so and that lives for 50 years and we have to come up with what we should build in there So this triangular shape here like this Just is tunnels nothing in yet there and in there we have to build interferometers again And just a tunnel size is enormous. So if you look at the end station here where all these tunnels come together This little dot there is a person So this is expensive and we have to get it right and We have this this same structure as before where there's vacuum tanks that got bigger They're vacuum tubes connecting these things But the key of course is how to arrange them such that they are cost efficient So that's a little bit different work from my usual optics, but it's interesting So it's more project management where I tried to squeeze them into each other so that you they cost less But still you then of course have to make very sensitive interferometer So that there's a kind of work that you have to do You can't hand it over to a tunnel engineer because you wouldn't know what the interferometry needs So you can find again on the same web page An interactive graphic where you can actually see all the optics So this is zoom zoom of a picture where you see all these mirrors in the ancient telescope and why again I think it's a good example is this triangular shape that the the way the interferometers are aligned in this very big European project all Based on papers that are written by my students not only mine But let's say 10 people and two of them were in Birmingham two of them were in Glasgow Two of them were in Hanover and these people will define the shape of something which is going to be built Hopefully in 20 years somewhere in Europe on the ground So this is kind of what I call a high impact of your of your sitting down at desk and thinking work you can do So that's more or less close to the end. I hope I have got two messages across Science is a slow process So sometimes that's not so clear when you see these big things that we are actually needing years and decades And another decade to get from a to be but that is how it is it can't be rushed but in all these big Projects or smaller projects if you are a PhD student You can have a big impact and your work will really define a shape of huge machines somewhere on the planet And what we detect with them and with that I would like to thank you and all this stuff you've seen they kind of crushed demonstration the simulations I wrote Something about gravitation waves you find on this web page. So if you have questions afterwards, please go there or contact me. Thank you very much