Gravitational waves are ripples in spacetime caused by massive cosmic events like colliding black holes, and LIGO (Laser Interferometer Gravitational-Wave Observatory) detects these waves by measuring changes in length smaller than the width of a proton. The first direct detection in 2015 revealed that black holes can merge and produce signals that travel across the universe for hundreds of millions of years before reaching Earth. LIGO India, currently under construction in Hingoli, Maharashtra, will be the first AI-controlled gravitational wave detector in the world, representing a new generation of instruments that will be more sensitive than current facilities and enable scientists to 'hear' the universe in ways that electromagnetic telescopes cannot.
The most sensitive device in the world - Rana Adhikari, Caltech
Added:Okay. Uh good evening everyone.
Good evening everyone.
Uh happy to see all of you here. Uh we are beginning our next uh series of public lecture which is Chundra public lecture. uh Chundra public lecture basically it's in honor of uh the great noble subman and you are also sitting chandra auditorium uh uh through these lectures we bring uh eminent scientists and researchers from across the world they talk about cutting technology and the recent advancements in science particularly astrophysics today we have one more such embellent personality with us uh to introduce him on the stage. I request Dr. Suri from to come on the stage and introduce our guest.
Hello, good evening and welcome to all of you.
Very happy to see all of you.
Uh for most of us who have uh been working in the field of gravitational wave detection. Ghana is a very familiar figure.
uh he has uh championed uh the growth of this field in in India and especially in bringing Lego India detector to India.
Uh he has been uh consistently over many years he has mentored and uh supported many Indian researchers to encourage them to enter this field and I'm proud to say I'm one of them.
I've known Rana since about 2010 since my uh days as a Caltech postoc and I think uh uh I I can count tens of students and posttos who have gone through this kind of a training. It's a very intense and steep ramp to uh learn this uh experimental techniques, the detector physics and a very deep knowledge of how very sensitive instruments are built. So I'm uh uh very happy and proud to be in a position to introduce Rana. Today I have [snorts] a short uh introduction that I would like to read out so that I don't miss anything.
Uh Rana is a professor of physics at the at Caltech and an experimental physicist who builds some of the most sensitive measuring instruments ever made. He uses them to ask whether our two deepest theories of nature, Einstein's gravity and quantum mechanics are really the last word or whether something new is hiding just beyond what we can currently measure.
He's among the scientists behind LIGO, the observatory that in 2015 uh made the first direct detection of gravitational waves.
Ripples in spaceime set off by two black holes colliding more than a billion light years away.
Sensing them meant measuring a change in length far smaller than the width of a single proton.
and much of his career has gone into the painstaking craft of making an instrument that quiet and that steady.
That discovery was recognized with the 2017 Nobel Prize in physics awarded to the founders of LIGO.
Today his group is building the next generation of these instruments by using modern AI and the new tools of quantum measurement. He's also deeply involved in LIGO India, the gravitational wave observatory now being built in Honda Maharashtra.
A project he has helped set in motion as part of the delegation that met Prime Minister Modi in Washington to sign the India US agreement behind it. Among his many honors in is the 2019 New Horizons in physics prize. With this I would like to welcome Professor Anadari to come and give the public talk today.
[applause] This is a test of my ability to do electronics. Well, I'm very happy to be here. I I have to say I've been coming to Aayuka for maybe almost 20 years.
I've never been into this auditorium. I think I've just watched it from across the street. I didn't even know what's happening in here. Um so as Sesh said I want to tell you about a few of these things. Gravitational waves this new project coming up in India and how we're going to do it. But uh I have to give you some background because this whole thing is like a story. I'm not really telling you a sc this is not a scientific lecture where I'm going to explain to you some physics. Instead I'm just telling you a story about physics more or less. So the story of physics is basically this uh story of the universe.
And when I point the point point at this thing, what I want you to think is that this is not the whole story. This is just the story so far. And the reason we put this up here is so that you can look at the story and say maybe I don't believe this part. And if you don't believe it, then you can come and work on it and see if it's true or not. So it's it's more like a broad story of science to say scientists go out there we observe the natural world and after we observe it we make up stories which we call theories that explain what we're seeing and sometimes very rarely somebody makes up a theory and then we go and do an experiment to see whether it's true or not. But most of the time it's the other way. We just observe something strange about the universe and then have to explain it. So I'm going to explain to you this story here today.
So, here we are in the modern time. We have the present universe. We're in a galaxy. The galaxy has a solar system.
The solar system has a sun and some planets. So, we're here. And but but how did this all start? We looked back into the night sky and we found, wow, there are stars out there which are really ancient, billions of years old. And then we looked at different frequencies and we found light that was in the infrared, microwave, radio waves, all of these kinds of things and put together a story about the universe. And that finally points back to this thing that we've all heard about, the Big Bang.
And I'm from that city, Pasadena, California, where they make that TV show that you've seen, The Big Bang Theory.
That's it. If you've seen that show, you understand everything. The rest of this lecture basically is already contained in that show. But what's going on in this big bang? I will tell you right away besides that television show, there is no such thing as a big bang theory.
What we have is the post big bang theory. We have a theory of what happened if there was a big bang. And that's of course my just my personal opinion, but I think we don't have any theory about what really this beginning was with the explosion. We think there was an explosion and there's a good story. But this initial part is kind of fuzzy still. That's I'm saying that as an official scientist. But after the big bang, let's say there was a big bang.
There was a huge amount of energy. And when there's a huge amount of energy, what really happens in the universe? Why does all of this stuff happen? Why are there particles? Why do we exist? What what's all this about? Is very mysterious. And you can read a lot of textbooks about it. But I'll explain to you in a simple way. If you have an instrument that's that's a stringed instrument and if you hit it with your finger, it makes a noise like and all the frequencies of that musical instrument are excited at the same time.
And it's because you made a sound like this. And that sound contains all of the possible frequencies. So the big bang is an event like that where there is so much energy that all possible particles are created. Protons, neutrons, electrons, all of these things. And maybe, we're not sure, but maybe also at the beginning of the universe, black holes were created. And the way to think about this is the electron is tiny. The electron has a little bit of energy. You can make it even if the big bang was soft. If instead of a big bang, it was just a thump like this. But if the bang was really sharp like this, then it could make particles that are heavier and heavier and heavier. And the way you should think about it is things which are higher frequency, it means they're higher energy. pretty much always. So, the highest energies, depending on how sharp the bang was, could have created things that are large. They could have created even something like me, but I'm not that old. So, not me.
Oh, good idea. The the man has given me a laser because he thinks I need more lasers.
Okay, so this is a good question. Um there's this famous uh French artist Paul Gogan and he has this great painting. I wish I had put it here uh which is called who are we uh where did we come from and where are we going and it's kind of a thing showing the tapestry of life. It's very confusing thing um but I want to talk about where did we come from to give the background for why black holes and gravitational waves and all this stuff matters. So this uh I said it began in this big bang and now if we look into the night sky what happens mostly you see it's dark and then you see things like stars moons that kind of thing satellites that's only in in what we can see with our eyes if you look into the parts of the night sky that are the darkest there's nothing going on there and you look at what happening in the microwave sort of radio waves world like gigahertz almost where where cell phones are operating the night sky looks like this that if you look at some parts it's cold, some parts it's hot. But this image is maybe a little bit deceiving. It makes it look like the night sky is very uneven.
What's the truth is that if you look at all the dark places in the universe, the radiation is almost the same to less than 1%. The radiation from this part of the sky and this part of the sky are different. Less than.1%. So the whole universe, if you look at it through the eyes of microwaves, it looks like you're looking at an explosion. It looks like there was an explosion and now as the explosion is fading out, we happen to be looking into the night sky. And that's basically what happens. That's the theory of why we think there was a big bang because it looks like when you look at the sky, there was an explosion. It's just that the explosion is now so cold that we can't see it with our eye. But if it was something like 10 billion years ago and we looked into the night sky, it would just be red. The whole night sky would be red. And that's that's why we think there was a big bang. And after that bang, it was just like this. It was just a big fireball.
And that fireball cooled. And those cooling particles of the fireball is what made everything here, all of us, and all of the things that we see. And that's the that's sort of the story I want to tell you today. So this is the periodic table of elements. You may remember it from school. Um since I was in school, there are new elements. This whole I think I think when I was the age of some of you, I maybe it was only here. It was maybe this was the biggest thing. And now we have all these other new elements. And whenever I look at this table, I don't know if this happens to you, but you might say, well, okay, here are these these things are all light, hydrogen, helium, you have all of these things, boron, nitrogen, so on.
Then nobody knows what these things are.
Osmium, rutinium, I don't even know these names. And then finally there's other ones, complicated names. Americ fit into these gaps here. But then what happens at the biggest one 118? Why does it stop at 118? Is it is it possible that if you added one more proton to 118 it wouldn't work? If you ask me, this is just my opinion again, but I think there has to be more to this story. That the next time you come here, whoever's youngest, by the time you're my age, you should be having to explain to somebody else why this new row is there in the periodic table and where does it come from? But how would we discover anything like that? Just, you know, this we we only had this when I was in school. And how did this all happen? These are incredibly hard to make. And you can see they have names like Moscow because only the really hardworking Russians are able to make this element Moscow. They're really into this. But even they can't make anything that's beyond 118 or 120.
And so we need some kind of new device because it looks like you probably would have to destroy the whole planet if you wanted to make something that's bigger than this on the periodic table. But I mean, wouldn't you like to have periodic table elements that are bigger than that? I would. So this is this is what happened actually. So there are these objects called neutron stars and they're basically things that are the size of this city. They're in outer space and they're something like thousand times heavier than the whole planet earth but they're only the size of this city.
Super dense like a atom like the nucleus of an atom but the size of a city. And those things occasionally smash together. And when they do, there is an explosion which is as bright an explosion as there has ever been since the beginning of the universe. It's so bright. And when the explosion is that much, it's like all the protons and neutrons smashing together. It's like the big bang story I told you about.
Because it's so much of a bang and so much energy, you can make almost anything. And so when this explosion happens, there is light, there's heat, x-rays, gamma rays, all kinds of things.
and also the synthesis of new chemical elements. And so with our gravitational wave detector, we found one of these and everybody else on the planet looked at it. It was one of the most unifying events in astronomy. I would say probably something like 5,000 astronomers all across the planet observed this one thing that we found in 2017. And after looking at that thing, the astronomers were able to find okay actually all of these elements that were mysterious for us and we don't even have this bottom row here but all of these ones like 80 90 and so on. So important elements that are in your smartphones and watches and things like that. These elements were created in outer space by the smashing of neutron stars. And in fact the magnets that everybody has, those are neodymium magnets. That's the name of the element. Neodymium is made by the smashing of neutron stars. So the magnets on the planet Earth didn't arise here. It's probably in a different galaxy in some place, maybe this galaxy, but some neutron stars smashed together and the dust percolated throughout the galaxy and eventually cooled into this planet that we have. And on this planet we have things like uranium and neodymium only because of the smashing of things like neutron stars. And for all of you who have gold, uh, I'm sure a lot of you have gold here today. Uh, part of that gold was made in outer space. Almost all of it was made in outer space. Part of it was made in supernovas and part of it was made in merging neutron stars. So you all have some kind of, not all, but most of you have some kind of astrophysical material on your finger maybe right now, which is amazing, I think.
So this is a great place to give this talk because I'm really just talking about Chandra and his work and what we've done since. So he's worked on many things. I think people know him mainly because of his work on these things, white dwarfs and black holes. So what is a white dwarf? I'll I'll tell you. We have our our star, the sun. And one of these days, not while we're alive, but maybe hundreds of million years or billion years from now, that sun will sort of run out of fuel. and then it will start to change colors and things like that. There are some stars that eventually run out of fuel, not like our sun, but other stars that when that happens, they're no longer burning and eventually it just shrinks and shrinks and shrinks because it's running out of fuel and all of the material comes together and it's just sitting there on top of itself. And the gravity is so strong that it would crush any one of us on that surface. And those things those white dwarfs are something like again the mass of the sun but only 100 kilometers in size 100 kilometers so just uh like this state or something like this part of the state and that thing is so dense people didn't know what would happen um and Chandra was the one who pointed out what was the real limits of that kind of system and how does it work and that was the first kind of really incredible star that anybody knew about and to explain why that star works and why is it so big and why is it so heavy You have to bring in the new science or it was new 100 years ago, the new science of quantum mechanics and the whole idea of quantum entanglement and now you know every store that you go to in the city will sell you something quantum because they just attached the word quantum on any object you can get.
But quantum has a real meaning and it was really the the thing that could explain white dwarfs and what's going on. Uh but the second part I think maybe people don't know about. So in the 1970s when I was sort of first starting to explore the natural world, he came to California and would stay at Caltech and work with the students who were there.
And the whole theory of black holes and what happens if you shake black holes was developed then in the 1970s when Chandra came to California and and I've talked to people there about it and uh well if I have time I'll tell you that story at the end. So the the year was something like 1905 I think when uh Einstein first published his sto uh I was going to say story but theory of relativity we would say and that was one of those a lot of people I think at the time were thinking about relativistic ideas but he was the first one to say it's not just mathematics there's something really strange going on and the speed of light is it the speed of light seems to be a real limit for us and if we assume it's true then our ideas about space and time have been wrong. And I was uh I wasn't even a university student. I was just at home with my parents. And I had this book about the meaning of relativity which I got from the local library. I looked at that book and I said, "What a crazy idea. How could it be that if you go faster then your mass increases and time slows down? It all seems like stories in science fiction." So I was determined, this is maybe 30 years ago now. I was determined that I would finally prove this person wrong because how could it be that any of that's right? We you're driving I mean you can't drive that fast in this city but if you get out of this city you could drive fast time doesn't slow down right time just keeps on going at the same rate. None of us have ever experienced anything like time slowing down. He also predicted something like if you're on the Earth, you will age slower than if you're in space. Or if you live at lower latitude and you're closer to the Earth, you'll age slower than somebody who lives on a mountain.
I mean, come on. This sounds like a complete fake news. So, I thought I should get to the bottom of it. So, I entered university. I thought it would take a few years and I would just figure it out. Um, it did not. Um, so while I was struggling to understand this in school, I realized I had only understood about 1% of the real meaning of the idea of relativity. It wasn't just about the speed of light and space and time and something like that. It was about the fact that our basic ideas of even distance and gravity, all of these things were connected in some kind of way that is is nothing like our usual physical experience. Which is why when somebody's smart, someone says, "Wow, look at Einstein over there. How smart that guy is."
But I just wanted to tell you by the end of this lecture, I hope that you'll get it and it won't be such a mystery to you and you won't think that somebody with this kind of hairdo has to be the smartest person. So what is the idea of gravitational waves in relativity?
Einstein said we if we take this idea that the speed of light is constant, light never slows down, it never goes faster or anything like that. Then we have to admit that uh you basically mass when you have mass you can you can bend light you can change the way time progresses and that description is really different from the gravity that we learn in school like Isaac Newton and the apple is falling and at the time it was really I think very controversial and I would say in the whole history of physics for me this was one of these moments of real genius this thing about speed of light and time and so maybe other people had that idea but Einstein was the only one to say uh this is not just a mathematical curiosity but it's something real about nature that we should really really understand um and one of the things that he wrote about in 1916 was this idea that just like waves on water if you push on the water there's some waves that you see he said if you take a heavy mass and you move it like this there will be a wave of gravity that propagates across the universe at the speed of light and then when he wrote this article he said, "It's nice. You know, I think this is the way it is, but it will never be measured because it's so small. It's nothing worth even talking about." And that was sort of the end. And he didn't even know, I think, if it was real, but he thought about it. So Einstein predicts these waves. This is 1916. Um, and then really nothing happens for a long time. People theorize about it, but it's kind of it's a thing that's that's a mathematical exercise sort of. Um and there's a there's a conference that happens in the US in 1957 where finally everybody comes together and they make some physical arguments and convince themselves basically from the argument of one student Felix Pirani and they said no no now we believe it that gravity can travel as a wave just like water waves and electromagnetic waves and the sound waves that you're hearing from me. It's just a kind of wave that no one's ever found before. Uh, and so this man, Joseph Weber, uh, he said, you know, every time I work on some piece of scientific research, somebody gets there ahead of me and then I miss out on the Nobel Prize. So, I'm going to work on some area of science that nobody else wants to work on because nobody even believes in it and no one will try to take this from me. And so, he started and he thought he had detected gravitational waves probably like 1965.
And it turned out that that was an error. It wasn't real, but everybody in the world got excited. There was a moment where I think he was probably the most famous scientist in the world, a living scientist. And this would have been something like 1968 or something like that. It was all over the newspapers, everything like that. And then it came to be realized throughout the 1970s that it was probably just a technical error, which is bad for Joe, of course. He was really upset about this. But I I'm just telling you this story not to make fun at him. he was a nice person but uh it was a mistake but because it was such an exciting mistake and we didn't know it was a mistake everybody else got involved with it and then the experiment actually worked so it started from a mistake so mistakes are not that bad um then then came along Raywise this is my mentor and guide in in my PhD program and he had they had known each other and he looked at it and said well your techniques are fine but I have a better idea let's use lasers' because lasers were a brand new technology in those 1960s.
Uh and so he started talking about it but nobody was still in favor of it but then he met uh Kip Thorne in the 197 early 1970s and they were forced to share a hotel room because they were in some place there were some meeting and there weren't enough hotel rooms so they had to share a room one night and they didn't know what else to talk about so they talked about this experiment and that was the beginning of this entire project which has now turned into like1 billion US dollars experiment and so Let let me explain a little bit how this works. Uh the mathematics of relativity is really difficult but you don't need to understand all of that to understand how this works. Um here we are on the earth and if you go to the coast uh as the moon goes around the earth you'll see that the water bulges. So wherever the moon is the water gets pulled a little bit toward the earth and that's the tide. And as the moon goes around and around like this the tide also moves around to follow the moon. And there's some lag, but basically the gravity from the moon to the earth comes almost instantaneously.
Uh, and then it takes some time for the water to respond. And so you can imagine if I take the moon and I move it back and forth like this, then the gravity here will move back and forth. So that's the basic the concept of what we're talking about. In the same way that we can make electromagnetic waves by using radio antennas, we can also move masses like this and it will change the actual fabric of spaceime and actually change gravity and pull things and stretch them and you can physically feel it. And the gravity from the moon is incredibly strong and the gravity from something that's on a different side of the universe is incredibly weak. But this is the first kind of gravity measurement that I think we're all familiar with that the waves on the ocean are coming back and forth and there's a low tide and a high tide and it's just this gravitational field from the moon.
Um so now imagine that here you are on the earth and let's say we have two moons and the two moons are orbiting around each other like this.
Now what are you going to feel? You'll feel the same kind of gravity from that tide picture but it'll be slowly moving like this. Let's see if I can time myself.
Look at that. What accuracy?
Yeah. So, this this orbiting of the moon, this orbiting of masses can make a fluctuation of gravity. And that's basically the origin of gravitational waves. When we look into the night sky, basically we see dots of light. But when astronomers look at those dots, what they find is that roughly half the stars in our galaxy are binaries. They're in pairs like this. And so a lot of the sources that we find are actually binary like this. And so all the gravitational waves that we see are from from binary systems. So this is a little bit of an image of what that looks like. Here is just us on the earth. And this is the idea of curve spacetime that I want you to get. So this is is hard to imagine I think because we're talking about the fourth dimension or something. But between two dimensions and three dimensions this is the idea. If you take a ball, heavy ball like this and you put it on your bed at home, the bed will bend. And that's just due to the mass.
And now in this bent space, if you throw a marble or something like that, it'll pass by and bend a little bit and go this way and this way. And this phenomenon about bent space and the curving of light is the reason Einstein became famous. He predicted this bending around uh around the sun and that was observed in 1920. And it's the same phenomenon that we're finding, the bending of space.
Um recently, uh radio astronomers, they used radio telescopes much like the the GMRT that was developed here in Pune and other other radio telescopes like that to make this radio image of a black hole for the first time. And this is not the one in our galaxy, but it's a it's a different one, but it's a very massive one. And they and they saw what we've only theorized up until then, that there's something out there which is incredibly heavy and contains all of this plasma, but it's dark in the middle. And what is that thing? What does it look like? How do we even find out what that is in some kind of detail?
Well, I'll tell you about this experiment that we've now developed after all those decades. So, those people I showed you, uh, Ray Wise, Kipth Thorne, they started this effort [clears throat] to build this L-shaped device in, let's say, 1975.
And this is what the detector looked like in maybe 2005 or something. So maybe 30, 40 years of just working and working and working to develop it. But the experiment was incredibly hard to do. And why is that? Well, just look at the scale of this thing. There's a building in here. There's a laser beam.
And the laser beam is split in two and it goes this way and this way. And from this image, it's a little bit difficult to see what the size is, but if you zoom in here a little bit and look at these small dots, these are fullsize automobiles. So that's the scale. This is a huge building and this is a 4 km long tube. And the tube is one of the most amazing things. It's the most empty tube that that anybody's ever made.
There's no air inside of here. All the molecules have been removed so the laser light can pass through without scattering from the air. And how do you make something like that? It's a solid piece of steel 4 km long, 1 m in diameter. And we're building one of these in India just now.
uh which uh I should I should say we were hoping to build one of these in India. We're starting to build one of these but it's not built yet. Uh but let me give you some idea of size scales. I'm talking about protons and galaxies and things and it's hard to see what these mean. So that previous image was a few meters. Uh we're now getting to be a million times smaller than myself. Uh finally we're down here to the corona virus. 100 nanometers, millions of times smaller than people. I don't even have an image of an atom. It's so small. And then finally, if you get to be 100,000 times smaller than an atom, you have a nucleus. So those are all the size. And then if you get thousand times smaller than that, finally you get to the level of measurements that we were talking about. So those gravity measurements, the things from the tides that I was showing you, you know, in the Mumbai coast, you get maybe a few meters of tide going up and down from the moon.
That's at this scale. What I'm saying is if you divide by 100,000, then 100 more, then thousand more, then 100 million more, finally you get to the size that we were talking about. So we need some sort of way to measure things that are billion times smaller than molecules, billion times smaller than molecules.
And when I was in school and getting into this, starting to learn about this thing, people kept saying this number to me, billion times smaller than an atom.
And I said, uh, I think that's not possible. You can't, if you have a measurement stick, meter stick, and it has ticks of 1 millimeter, how can you know if something's smaller than a millimeter? You can't be billion times smaller than a millimeter with a stick that has ticks of millimeter. That sounds impossible to me. So I thought maybe I'll work with these people for a year, but like this is not a career for me. I I thought that in 2001.
Uh so let's go the other direction and talk about the ridiculousness. So from people to Mount Everest, look at this.
Several kilometers. Now we're at thousands of kilometers, the size of India.
Now we zooming out. What's the size of the earth? It's it's like uh 10,000 km.
And then finally the distance to the moon uh 100 million meters. And the distance to the sun look at that eight light minutes. Still it's small in the planet. We're now getting the speed of light travel time across the solar system is like minutes and hours. Uh inside of the Milky Way galaxy is maybe hundreds of millions, hundreds of billions of solar systems like that. And then finally the whole observable universe, the universe is maybe trillions of trillions of galaxies of which they have trillions and trillions of stars. So it's trillions upon trillions. The size of the universe is one of those things that I think no matter how much I talk about it, I tell you all these numbers in trillions. It's a concept I can't hold inside of my mind. It's just too big. I can understand maybe million, but I can't understand this thing. Billions and billions. How many billions can you say?
So, but that's why we use these numbers.
When we say 10 0 10 the 6 this means something like one and then six zeros meters. So, it's that how many zeros are in the number? That's what that means.
So the size of the universe is 1 27 zeros m that many meters that's the size of the universe that we can see today but probably the real universe is larger and so the kinds of signals we're looking for are coming from completely from the edge of the universe and they're coming to the earth and we're proposing to measure these signals which are smaller than the smallest things that exist. So that's the scale of the challenge. Everything is incredibly weak and and they're incredibly distant.
How do I advance my slide?
Okay, so um I'm trying to give you a little bit of the feeling that I had doing this. So it's uh I I got into university. This is maybe in the late 1990s. and I heard about this project but I didn't really do anything. Uh and then I went to MIT for my PhD. Um and I started working with this man Rainor Weiss. And then I started slowly to understand how difficult this was going to be. And each time we thought we had some sort of measurement we were something like 100,000 times worse than what we needed to be. And this is to say at this point the US government has invested 300 million US dollars into this project.
And then after a couple of years, I realized it it's something like I I don't know what to say. It's like if somebody sells you a washing machine and says that it's going to give you 99% dry or something like that and instead of 99% dry, you just get 1% dry. That's kind of what that instrument was after 300 million US. And I thought this is not a good career for me. This is not working. I should find something to do that's more practical. Um but then but then I didn't um and 2005 comes along, 2010 comes along and I asked my guide what to do you know I I started this I started this adventure with you in 1998 and you told me it would take 3 years uh and now it's been something like 10 years and he said to me he said it's right around the corner if you just wait one more year we're going to find it and I said okay it's 2010 I said 2011 11 12 I can wait that long fine and waiting and waiting and by that time I had my own students and my own students said to me sir like it's been 3 years you know I have to get a job what am I going to do and I said no no no listen everyone who said that to me they were wrong but I am very smart and I'm telling you it's going to be just a few more years and I kept saying that for maybe seven years. Uh but in 2013 when I said it, I was right because then it was only a few years away. So if you just keep repeating the same thing, eventually you can be right just like a broken clock. Uh and this is this is what happened. So in 2015, we all been working on the detector. I'm taking a lot of time off from teaching to go work on this machine. And then finally in September, I said, I have enough. Like I'm exhausted. I just need a break. I'll just go someplace and relax for a while. And as soon as I did that, I got text message that said, "Oh, it seems we have a signal that has arrived." And I said, "Listen, people, you are all young people. You don't understand how it works. I've been doing this for so long. I've seen a lot of fake signals. You know, it's not real.
It's not real. Just go back and and check." And then a few hours later, I think it's I think it's real. It looks very good. I said, "It's not very good.
And I'm on vacation. Please just leave me alone. check your homework. I'm sure it's wrong. I'm sure it's wrong. And then, you know, a week goes by, two weeks goes by, and it's starting to get into the Twitter world. Everyone was reading, have we heard some rumors? Is something going on? And people would come and ask me, hey, is it true? Like, some black holes have exploded. Is there a real signal from space? And then we were at that point where we don't want to have a leak. we have a signal and because of the story of Joe Weber where he said there's a detection and then he w you know and then it turned out to be fake. We all had this fear that what if what if we think we found something and then we announce it to the world and then tomorrow somebody finds a problem in our mathematics and says uh you know like two should be 2.2 or something and then it's and then it's wrong. So we just try to keep it secret and this is September of uh 2015.
October is coming along still. We just have this one signal and we're very very worried about what to do and now there's rumors going around and so when people would ask me about it I can't tell them no and I can't tell them yes. So I said I just tried to make them very bored. So they would ask me, Ra, tell me what's the what's the truth? And I would say, well, listen, let's go talk about statistics for a while. And this is a histogram and calculus. And and they say, okay, I don't care anymore. Leave me alone. And so that's how I avoided the press release. Uh but finally in February of 2016, we released this image to the world. And this is this is the real signal and this is what it looks like. So this is time something like quarter of a second. And on this axis is this quantity called strain. So it means if you have something that's 1 m long, how much does it change? And this is saying it changes by one part and 10^ the 21, which means in a 1 m stick, it's 0 and then 21 zeros and then one that many meters out of a meter stick.
Luckily, we had something that's 4,000 m. So the signal was bigger. But this is that number I was telling you, 10us 18 m. So this signal that we measured is thousand times smaller than the proton.
And we were able to detect it this well.
And this is one in the northwest of the US. And this is what showed up in the southeast of the US where I was mainly working. And we overlaid them to. And they look exactly like this. And uh the signal starts at a little bit of a low frequency and it comes to a high frequency. And then this ringing here is is of the final black hole. And I just want you to see that this thing takes only this few tenths of a second. And so the frequency at which it's wiggling is a frequency that you can hear with your ear. And so if your ear was something like uh 100 million times more sensitive than the best ears in this room, you would directly be able to hear this thing. And it sounds like just like that. You should applaud for that. Come on. That was very good.
[applause] There you go. That was one of my best.
Okay. And it was amazing. I thought we were working on sort of an obscure project and we had never found anything for decades and decades. And so nobody really cared about our work up until then. And it was great because no one ever asked us, "Have you done it right?
Have you not done it right?" They would say, "What's going on?" We would say, "Still nothing." And fine. Uh but then after this happened, we made this announcement and if you go and you look February 16th of 2016, the front page of all newspapers all over the world were about this event. What happened that there was the merger of two black holes which happened hundreds of millions of years ago. So I've been only working on it for you maybe like 17 years at that time which I thought was a really long time. But that signal had been coming toward the earth for hundreds of millions of years. Well before any people were here. There were nothing going on on the earth. And that thing happened and it just coming in.
It's just waiting for us to get together and get the technology together and do it. Uh and so it happened. This is the uh national press club in the US and full of all these scientists and reporters while this thing was announced which I thought was amazing. Uh and then in 2017 it the Nobel Prize was awarded to Kip Thorne, my guide uh Ray Weiss uh and then also Barry Barish. So I when I started graduate school, [clears throat] I visited him and I said uh you know I'd like to come in here and work and he said no no it's this like 199 I think 1998 and I don't know maybe he was see 1998 maybe like 65 years old 64 and he said you don't want to work with me I'm much too old and I have nothing to contribute anymore go find somebody younger to work with and I you know I came back around I said no no come I think I think and he said, "No, no, no.
I don't want anything to do with you. I I have I'm old and I have, you know, I'm I'm kind of done." And he said, "But tell me about yourself anyway." And I said, "Uh, you know, I'm very good student." And he said, "I don't care."
It's like, "You're all good students here." And I said, "Well, uh, I play music." And he said, "Okay, good. That's a good thing. What kind of music?" I said, "I play guitar." He said, "Fine, fine." And he said, "What else? What else have you done?" And he said, I said, 'Well, um, sometimes, uh, you know, outside of school, I work in this auto shop on the side of the road and we filled we we fix old automobiles and things. Then he got excited and he said, "Everybody get in here." He said, "We finally have a useful student that's arrived. Give him a job. Get him going.
Let me buy you a sandwich." And he was really excited from then. And and then we worked together for years after that.
And mainly because of this thing. He didn't care about my marks in school. he just carried that I was interested to do the work and we had a great time. So I learned everything I know about experimental physics from him and so this was 90 1998 but we kept on working together until 2025. So just imagine like at age 90 he was still telling us what to do. So any if any of you feel like you're too old I'm pretty sure you're not compared to him. Uh I came to Caltech uh and Barry Barerish was there and he was a great leader of scientific projects and he a great guy but he was not an expert in our field lasers and all of these things. He didn't know about the technical details but he understood how do you motivate people and get them to work on things and that I realized was the real magic beyond any of the physics and mathematics that we do. How do you take a crowd of 300 people who all have their own emotions and feelings and make them all move in one direction and work on one kind of thing? So, he just had this persuasive power when he would talk and say things to us quietly like, "Let's all go, let's go all go for lunch in this place." We would all go with him. And so, because of him, this whole project worked out.
And then finally, Kip Thorne, maybe the most well-known of all of these people.
people. I think everyone knows about him because his work in Hollywood and popular books and black holes and wormholes and time machines, but the main thing that I learned from him is he's just very kind. And no matter who was misbehaving in his group or how they were doing or something, he would always come by and say really well like, "You're very smart. You're doing a good job." And we'd all say, "Oh, okay. Keep thorough. I'm very smart." You know, they keep on going. So, they're master manipulators, I would say. And but I was I was glad that they got the Nobel Prize finally in the end. Um so I I want to tell you a little bit about myself. You heard this introduction already from Sesh, but he's uh I don't know he's it's like a revisionist history a little bit.
I don't think it's it's quite that clean. uh uh my parents moved to US in around 1970 and I was I was born there in uh 74 and it was a you only now that they're older and I'm hearing a little bit about their first experiences I understand how difficult it was they came from Kolkata they moved there there was nobody else there's no family members in the US and the US system is incredibly different especially compared to India back then it was completely self-suffic ition.
There's nobody in your home to help you with anything. So they had to learn everything like home repair, automobile repair, all of these things. And otherwise typical Bengali household machbat mishti that's the main thing. We learned chess, we learned how to play music, sing and dance, that kind of stuff. Uh but then the other hand, we were also going out and doing very non-Bengali things like running around in the dirt and getting dirty and always being greasy and fixing objects and things like that. So my early education was this kind of stuff. Be good at math and also fix that thing and fix that thing. And by the time I got into school, I thought, well, you know, I'm not the smartest person. Uh I'm not the fastest at mathematics, but you know, my whole path into experimental physics happened because of this funny merging that we had. This mix of doing things with your hands and also being uh interested in mathematics. So I would say if you really want to have success in experimental physics or astrophysics, that's all you need to do. Go work with your hands on something real and be excited about something like this. Um, enough about me. I want to tell you about how this uh came to India. So I came here uh I think in in the 1970s in the 1980s, but I had never been to Punea. I've always just been to Bengal. But in 200 I think in 2007 um this man Sanjit Mitra who's here in the front audience had met me in California and said maybe we should invite this person he looks vaguely Indian maybe he would come to a conference in Aayuka. Uh so I got an invitation to come and I thought do I want to go that far as to India. So I asked my parents, hey you know like I this conference in India things going on maybe you know we haven't been back home in a long time let me let's go. So me and my parents we came here uh and we we visited Pune and they were amazed they said look at this it's like where we're going to have fish in Pune it's not good like Kolkata. So then we went to uh Bengal. We visited my grandmother and they said uh you know and this was uh 2007 I think and everybody in the home was like what's going happening with you? It's 2007. Why aren't you married? There no girls in USA. We can find you one here. What's wrong? And my grandmother was there and at that time maybe she was 85 or something. They asked her what do you think? And she said why does he get need to get married? He's only like 18 years old. too early. Too early. And I said, "Good grandma. Protect me. Protect me from these people." And then she said to me, "It's very good. You're doing all this scientific work. We're all very proud of you, but why do you have to do it in this foreign land? Why can't you come back home and do it here?" He said, "And I had just been here and visited the good people of Aayuka." And I thought, you know, it's a good point.
Why not here? Why not here? Right? And there was a night right before I had to give a talk at Aayuka. This was at ICGC.
And uh Sanjit and I and our friend Anand Gupta, we were out uh having some good times at night and talking ourselves into some exciting things we do as young people. And we said, "Yeah, why not? Why don't we build this thing here?" And I think Anand came up with the idea of indigo. He said, "It would be great.
Like you have LIGO already. Let's make up this acronym indigo." I thought it was genius and then this airline company took the name from us and so we never used it but but um I think we had we had a we had a great success. Um but the road was long that was 2007 and here we are in 2026 and what went on and you know a lot of people have different recollections what what what happened but what I remember is that Sanjie Durand who's here in the audience he had this idea long back maybe like I mean we thought it was our idea but he had the idea already and there was an effort here between Aayuka and then our cat and indoor to make proposals they had ideas about building small detectors bigger machines all kinds of things but it might have been a little bit too early and the technology wasn't there but at this time when we started talking about it I traveled around all of India but at the time Ajit Kimbabi was the director here he thought you know uh I'm not sure about this but it sounds interesting it's worth pursuing and so we started traveling around India and it was mainly uh myself Tarun Surudep who's here uh Bala who was at RRI at the time Raman Research Institute and then Uni Krishnan from TIFFR and we started traveling all around the country of India and I started you know as an adult this was my first time traveling here and so I everything I know about India came from that uh years of travel from 2010 through 2015 basically going from university to university and saying let's do it let's do it uh and mostly what I heard was no you can't do it I said why why do you think we can't do it um well we didn't have anything actually there was no detector at the time. So I was just talking about doing it but there was nothing to do in some sense.
We didn't have it but the LIGO director in 2010 or 11 he said you know we have three of these instruments in the US but we only have two places to put it why don't we put something in Australia and then that's far away from us and then we can use it to detect things from all over in the universe. And I said, "Well, um, I know a different place we can put it, which is almost, uh, in the same location as Australia if you're looking from the US." So, it looks the same. And maybe it's a good deal. And everyone in the US said, "I don't know. Do they do anything? What's going on there? What's all about that country?" And I said, "Come on, like look at all this stuff. They all this gravity is going on. People are doing all these calculations." And they said, "Yeah, well, but that's fine, calculations and things, but this is a real machine. Somebody has to make it and make it work together." And so I was constantly, and of course, I didn't know the truth.
But I was constantly saying, "Yes, yes, don't worry." Like, "We'll do it. It'll be fine. Just just just give us the hardware. We'll do it. We can do it."
Uh, and around that time, Australia also really wanted to do it. But I don't know if you know this thing. Australia is a big country but in the whole of Australia there's only about 30 million people and in India there's a little bit more than 30 million people and so statistically I said we're more likely to find good people in this hand than we are in this hand if there's 300 more times people here um anyway we were going around and doing this I went to IPR in Gandhinagar and I think this is where it turned from a dream into something. So, Professor Kaw was there.
He was the director at that time and he uh the government of India had made this institute for him, the Institute of Plasma Research, which is now looking into this uh taco and thermonuclear fusion. And when we went and spoke to him, he got excited about it and he said uh this is such a great opportunity. The US is offering to give us a lot of components. We cannot afford as a nation to not do this. It's such a great opportunity. And I came here to Pune and I went to the great experimental physicist Govvin Sorup and he said listen American boy this is not how it works this is India is not as easy as you're making it out to be and I said uh and he gave me a lot of things he said what will happen if you you know if this happens how will you survive or if this happens how will you survive and I just kept saying him I I said you know I'm like you you know my history and where I'm from what do we when someone says says that we say coro lbo that's what we say so that's what I say [applause] it will be tough but we can do it we can do it um and then giant narle was here and tarun introduced me to him and we gave him the full pitch and he said uh he said of course you guys can do it look at you you're so smart you're good boys I said exactly like this is how Kip Thorne does it gets us working on something and and we did it. Um and at that time there was this huge pool of people who could do theoretical physics in India and it was great I thought but in experiment it was a little bit less I think there's like uh JC Bose and CV Raman and people like that who had done great experimental physics but mostly in the early part of the 20th century and I thought it's time to really make this work but you look at the history of CV Raman and the things that he did with lasers and light here we use it all the time if you go to any optical conference in the world.
Everyone is just saying that word all the time. The Raman effect, the Raman laser, the Raman like everything is named after him. And so I thought this is really what we can do.
Um so I want to give you a little bit of idea of the technical challenges that we face. So the ground here is moving by something like 1 millionth of a meter all the time. But I'm telling you that we have to measure something that's 1 billion times of 1 billion times smaller than a meter. And how to do it? It's it's like uh you have to remove so much noise to do it. But each one has a trick. So the ground is shaking, the ocean waves are going, the moon is swinging. Uh but we use vibration isolation systems and active vibration isolation systems to get rid of it. Uh the air itself is a problem. And as I mentioned, we use vacuum pumps and get that out of the way.
Um, finally you get down to the level of microfysics and the actual molecules in the instrument are vibrating all the time because of course we're trying to measure something that's uh a billion times smaller than atoms themselves. And how do you do that kind of thing? Well, we have to figure out how to make very exotic and pure pieces of glass. Like a like a piece of glass can ring like our pieces of glass are so good that they ring for something like one year.
they're that they're that pure. Uh and then finally the light itself and that gets the level of quantum mechanics and some of you who are in school have heard about the Heisenberg uncertainty principle and that's a final limit to how good you can do or so they would tell you your teachers would tell you but there's a trick and you can get around that also. Um and so I I like it I like to think about it like this.
There's so much noise in the room in the on the earth and we're trying to find this whisper and what do you do? It see it seems hopeless and it seemed hopeless to me many many years and many many times it seemed hopeless and we would do it and we would do it and we would get a little bit better and then we would get stuck and then sometimes for a year nothing would improved and that was the times many times I thought I should quit because it's not working and I should why don't I go into some other field where things are just easy why can't I just do something easy but we just kept on going and kept on going and that's what I would tell you anyone who thinks that you can't do this kind of a project in India. I would say it's just not true. What my experience is that if you just get together like 10 or 15 people who are really passionate about that thing, you can do it. You can do almost anything if you if you really just want to. Um so is it really impossible? Um well for the vacuum system these people on cause institute at the institute for plasma research have already doing uh ultra high vacuum systems to remove the air from systems and they just know how to do it and recently they've produced samples of the LIGO hardware and they're able to get the the vacuum that we need.
We also need to have very stable laser beams do these measurements and perfect pieces of glass polished polished so that the roughness on the glass is less than the size of one atom which also sounds impossible but they're able to do it already in indoor and I've seen I've seen the labs myself and then finally well okay it's very large and nobody in India has done this thing yet but we are not leaving you alone and as I I tell those people who told me to stop talking and lecturing about this I said I'm never going to stop coming back like I'm always flying here and I'm never going to stop until this project is done. Even if you cancel my project, I'll just come back again and do it. And the only way to get rid of me is to just finally do this project. And so all of the people from the US and all over the world are now going to be coming to India to work on this. And that's because everybody, every country, Europe, Japan, Australia, everyone knows that this LIGO detector in India is going to be the next most exciting thing in astrophysics that's coming anywhere. and this is the place to do it. So people who want to come here. Um and then the final thing which is really tough is this thing of how do you get people to work together but I would say this has already been done right we have ISRO and there are all these great missions. People are going to the moon and going into well maybe not people but things are going to the moon and things are going into space and those are really complicated projects but India has already shown that this can kind of thing can be done here. Um and then there's the GMRT itself. And this is I think what really gave me conference confidence. This is you know one of the biggest this is one dish but it's the biggest radio one of the biggest radio arrays in the world. 30 km in size and I always said we already have 30 km and we're just talking about building this 4 km thing. How can it be so tough? Not so bad. Um so anyway it's it's a great precision instrument and you know many things will come from having this LIGO in India but I think this is one of the easiest things to understand. So currently this is a map of the sky and this is looking like a north south and east west and if you have any of these events in the sky which are two black holes spinning together and making that woot sound that I made for you. If it's in this part of the sky, what this plot is showing you that we can only localize it to within 30 degrees. And if you look at the full moon in the sky, the full moon is like the size of your fingertip if you look at it. And that's about one degree. So one degree is something like this. And so what our simulations show is that if you take all the detectors in the world right now and you put them together, you'll still have places where you can't actually tell where things are coming from. And so the astronomers make fun of us because they say you LIGO people when you detect something and we ask you where did it come from you say over there someplace and we say this is a precision science you can't say over there someplace give us some numbers so I said this is the only way we can do it we need this thing in India and if we put it in there almost every place in the sky is going to be like the moon so that you can look into the sky and say it's like within this region and you can tell exactly where things are going and you've We've all seen pictures, I think, when people get uh uh ultrasound and you can see the baby inside and they're using acoustics in order to make an image of something on the inside. And that's really the purpose here. All of these signals sound like this whoop kind of thing. And they're happening all over the universe in different parts back into early cosmic time and nearby time.
And what are those sounds doing? They're like the baby's ultrasound. The black holes are making these sounds like whoop boop boop all the time. We found this one in 2015. We found another one on Christmas day in 2015 and that was two in that year. Since that time we found 400 signals and we expect by the time India comes on we'll have another 500.
With India we'll detect something like thousands and thousands of signals like that. So instead of being one whoop one whoop like this. It'll be like a continuous rain of signals. a continuous rain of black holes merging in the universe. And those sounds will propagate throughout the universe. And by listening to that echo, you'll be able to find out something unique about the shape of the universe. In this room, my voice is kind of echoing because of the shape of this room and the ceiling tiles, but you can close your eyes and you know that you're in an auditorium just from the sound. So the information that we get from this kind of thing is completely different from what any other astronomers get. They're seeing the universe, but we would be hearing the universe for the first time and using it to tell what kind of universe we're in.
What's the shape? And is the universe really three-dimensional or were there extra dimensions of space in the early universe? Did something change? All of these things you think about from science fiction. Those are the kinds of things that we would be able to find by having this detector in India. Uh so we're hoping to build it and uh well, not hoping anymore, I guess. I I say hoping anymore, but we it is now being built. Construction is going on in the eastern part of the state and this big facility will be there. Uh ground was broken just a few months ago and we expect to turn it on probably 2030, 2031 or something like that and start hearing the first signals from outer space. Um so [clears throat] it will feel hopeless.
uh schedule delays will happen, things will be hard, hardware will break. But I just want to say like if if [snorts] just the people in this room only and we had nobody else, I I would be highly confident that we can do it. If all of you would just stop what you're doing and we would just get on a bus and we go to Hingoli, then we can do this thing.
We don't need that many people, you know, like someone has to cook, someone has to do lasers, someone has to take care of housing, something like that.
But this group is already enough to do it. It's not that many people. It's a difficult project. And in the US, it took us a few hundreds of people. We had to import people from all the different countries in the world to get enough talent to do it. But this is a nation of 1.4 or more pe billion people. And I'm sure that we can find a few hundred talented people that make this kind of thing work. So, you know, don't worry about it. But I would say the main thing is you have to avoid getting distracted.
It's, you know, the difference between coherence and incoherence is everything.
If you know people are not able to do something in their own self-interests because you're being distracted by the outside, you know, that's the that's the thing. You need the willpower in order to isolate yourself from the noise of the rest of rest of the world and in order to do this great thing. I think we can do it. Um and it I think it's a great scientific opportunity of course and I I I hope I convince you of the astrophysical reason but I think the other point is a little bit uh more soft which is you know why is there all this great technological development all over the world? It's because people are inspired by something that's bigger than themselves. And in the US, maybe 50, 60 years ago, this happened because of the urge to go into space. And not everybody went into space, but the technology that was developed to go into space was so wonderful that it permeated throughout society. And it led to great wealth and economic development. So, I hope that for this project, it's a great thing.
And black holes are wonderful. And I mean, as you can tell, I love black holes, but there's more to life than black holes. And I I hope that's what we make with this kind of thing. So, I hope people get together to build all of the technology to do this, but then we can actually turn it into some businesses and economic products. We'll be able to fabricate fantastic materials, uh, communications technology, cryptography, quantum science, and then finally, we are doing this now in 2026, right? is not 2015 when we first did in the US and the world has moved on. It's not like it was before and so this detector in India will be the first AI first uh gravitational wave detector and by which I mean the complicated instrument should be controlled by a mixture of human and artificial intelligence in the in the future and that will be a revolution in speed from what we were doing in the US.
So this is not us taking components from the US and just assembling it like uh in a mechanical way, but we're innovating and making it much better. And based on my estimates, this will be the most sensitive detector in the world beyond what's happening in the US right now because they're starting from a standpoint which is 2015 and they're improving from there. We're starting fresh now. So all of the lessons learned are already incorporated.
Uh and there's no power that can stop us. So um I think people ask me this thing, how can we ever get to that point? You had all these Nobel Prize winners and things going on, but if you talk to them all, it didn't matter where they started from. Their initial condition was wiped out by the fact that they landed in a good place that was a good environment where people were trying to encourage them to move on. Um, and so it's more important how fast you're moving or how fast you're learning than what you're what do you know today. And and and maybe more important than that is how fast you learn how to learn. So you if you're in school and you're learning, I think the most important skill for you to learn is to find out what's the type of learning that's best for you and then change your education so that you use that kind of style. But uh a little bit of effort in learning how to learn now will make your position that much greater in the future. It's a slow start, but it's I think it's the right way to get there.
Um so I'll just conclude there to say I think this is the most sensitive device that humanity has ever created. It gives us a great way to look into the future and and look into outer space and find out what the universe is really about.
But the technology that we have to develop to do this are the are the great leading technologies of today. Quantum materials, quantum measurement and artificial intelligence and India is definitely the best place in the world to do this kind of thing with the talent pool that we have. And I think the resources that are now available to do this are are what we need to do it. I find it to be very exciting. I as I as I tell people every year, this won't be my last visit. So if you want to argue with me, I will keep arguing with you. But in five years, we'll have the first detection of black holes in Indian soil and be done by people here in this room.
So I look forward to it and then I'll come back and tell you about it when it happens. Uh so thank you for your time.
[applause] >> Okay. Yeah. So that was uh an amazing and very inspiring job. I'm very sure that you'll have some questions. Uh we have Susan here and you can raise your hand. Keep your hand raised and they will come to you for this for the questions.
Yes. Uh sir, I wanted to ask that uh you know in events uh where electromagnetic fall off happens after the gravitational wave is detected.
How origin is uh that uh window and uh what is the present mechanism uh in place to have various ground and space-based telescopes to interrupt what we are otherwise doing and reorient themselves to uh do the right >> yeah it's a important [clears throat] point I think you're asking something like there's a there's many different kinds of astronomical telescopes which can observe these kind of events and how do we synchronize all of that so that we're doing it uh well together >> yeah u so for a lot of these events it's extremely urgent you need as soon as the thing is happening you really should have already been looking at that part in the sky for probably 30 minutes so you need to go back into the past if you could So we have to find a way that before the event happens to predict it's going to happen. So the current idea is that we need to combine all of electromagnetic astronomy optical and radio and all of those things and try to predict the events by looking in some of the other bands. But once it's happened and we are detecting something with this device, there's an electromagnetic alert that goes to all the telescopes in the world. It's a public release and then everyone gets to choose if they want to do anything. But we make agreements with all of the telescopes that can move quickly and tell them, "Okay, we're going to give you a signal and we promise you that nine times out of 10 it's going to be a real alert and maybe one times out of 10 it will be a mistake." And so that's an agreement that they've said that's fine. We'll be able to look and but but the time scale is something like few seconds depending on what wavelength.
>> Hello. So first of all I didn't expect myself to be here in front of I mean in the stage talking to you the time when I watched very video in which you were there. I mean it was funny because in the video it was like clearly you had I mean experiment.
So what made you like wait this long for that thing for the singer to come and >> you mean why didn't I quit?
>> Yeah.
>> Oh uh no no I yeah exactly I tried to quit many times. I thought every few years I'd say maybe maybe this other flower smells sweeter than my flower so I should go smell. But um I would say you know um distance makes the heart grow fonder. So sometimes I would stray into some other area but then I would realize I was already in a good place because when I would complain to the other astronomers and say you know your life is so easy you just point your thing over there and you find things all the time. why life is so hard for me. I never find anything. And they will always say when you find something it's going to be profound and we find things all the day. So no big deal. That was it that the feeling that the reward is worth the wait.
>> And also one thing like signal is coming from millions of light years away. So just like any other signal or the wave, why doesn't it disappear? Like we can see in the water the waves >> they just like.
>> Yeah. after which it is still water or something like that. So what about the gravitational wave like why >> why yeah that's a it's a deep question about the true nature of the universe or something like that. Um, you know, if if I'm standing here and I do like this, that wave travels across the wood in a certain way, mostly traveling on the surface, but it's getting a bit attenuated because it also goes down.
So, some of the energy is leaking into the into the bottom of the stage and not just traveling across the surface. And so, the signature that you're talking about would be if the universe really has three dimensions of space like left, right, up, down, then there's no wave.
the wave can't go anywhere and dissipate. But I've always suspected that if there's an extra dimension of space that the gravitational wave would really give us the evidence and that we would see it in some kind of change modification or something like that. But uh you know I I'm as I told you like I'm waiting now 30 years to disprove Einstein. So far he's still right but I'm waiting for what you're talking about that some kind of little variation will happen. So uh don't give up hope.
>> Yeah. And also one thing, how sensitive is the India?
>> Sir, I have a question.
>> Yeah.
>> Yes.
>> Can I ask?
>> Yes. Yeah. Sir I I think I missed but what is the full form of FLO first of all and the second question is uh you told that of course the gravitational this device would would be the most sensitive device but what would be the major applications so as to I understood I am a microbiologist I understood the importance of measuring the gravitational waves but what would be the major applications which you are looking at >> yeah LIGO stands for laser interferometer gravitational wave observatory. I should have mentioned uh laser interferometer just means we use light interference and gravitational this you know the major application is really this astrophysics black holes and gravitational waves but I'll give you a few examples why why it can do something more so the measurement technology already is profound and we use it all over the place so all the technology that was developed to do this has already been put into other areas so the whole field of quantum computing which has happened largely was driven by the fact that people like Kip Thorne were looking into how to measure this thing better in 1980 already thinking about quantum entanglement for measurement and so you I mean you can ask what quantum computing is good for I guess but we we hope that's good for something I think the other side of it is that um this is a little bit of a wild idea but I'll just tell you about it now we are sensitive to gravity and we can't tell the difference between gravity from people and gravity from outer space gravity Gravity is gravity as far as we know. One of the things that's I I always you know for me personally I think we need to do for humanity is that we cannot anymore allow ourselves to be injured by this uh tsunami which kills so many people. We need a way to have really early warning. But the problem is that when you have earthquakes the time for the speed of sound for that earthquake to travel through the ground is really a long time. It can be tens of minutes or something like that. But gravity travels at the speed of light.
So if you have a sensitive gravity sensors all over the world, then as soon as there's the earthquake and before you feel anything, you know exactly what happened and where on the earth it happened. And then you can compute these things ahead of time. And even if people can't move that fast, you can give them something like 10 minutes of time like by text message to go hide, do something, whatever the instruction is, you can give them some kind of information. I think even if we never detect a surprise in gravity, if we could detect gravity on the earth in that way, that would pay for this entire detector 10 times easily.
Hello. Yeah.
So, my question might be right because I am not from the field of physics or in fact I am not from the field of science.
I'm an art student but because I'm curious that's why I'm here. So as we are a curious race as Khan Sean said will we be ever able to understand the mystery of universe of the time in fact time was created at the big bang but the idea [clears throat] what was before uh the big bang is singularity real or for example how will we able to converse the theory of everything as being said >> I know This has a very large answer and this might not even relate to your field but still uh will be able to understand >> what was before similarity or uh the very early years before it was really created.
>> Yeah, I I don't have a sure answer for you but I'll give you an answer anyway.
We physically with our eyes we we don't see anything even close to the big bang.
what we the the last thing that we see happened 300,000 years after the big bang but how are we extrapolating to the beginning from this later image and it's really the story of science so I think sometimes when we communicate this science it's a little bit too much hype so I want to give you the real answer when we're doing science we observe some facts and some measurements and we do the best we can statistically to make the best estimate based on what that means but you just have some information so imagine you look in this room and your eyes are closed And then you get one image like that, this brief thing. And then someone asks you later, what did you see and you have to create some kind of story from this brief flash? And that's kind of the story of science. We have little bits of information and we try to make the best story that we can from that. And so what we've said is that if the big bang happened in this way, it would predict what we see today. But in actuality, there's no way to directly observe that beginning almost. And the reason for that is that the the explosion happens and the it's a fireball explosion like you see in movies or something. You can't see inside of the fireball. But one thing that passes through the fireball is gravity. So gravitational waves if LIGO India detector really works.
We still won't be able to see the big bang. But if we put something like this in space, then we would. So there's an idea to to take multiple of this LIGO India thing and put it into space and if that you would be able to hear finally using gravity the initial the sound of the initial explosion from the big bang and that won't be exactly at singularity but it'll be something like one nancond after the big bang. So that's as far as I know how to look. So my ambition before I retire is that we'll find that initial pop of the big bang.
I would like to ask two questions.
First you stated that principle can be work around. Can you explain about that?
>> Can you say again? Work around what?
>> Oh yeah yeah yeah. Um let's see.
Um, you know, sometimes like uh like my mother would come into my room and say, "Your room is so messy." And uh what you know, what's my strategy is I would just take everything and put it underneath the bed and just hide it and say, "No, no, it's not messy." So that's that's basically the trick. The Heisenberg uncertainty principle tells us if you observe some particle, you can understand if you shine a light at it, you can see where it is. But if you make the light too bright to look at that particle, then the light itself shakes that particle around. So there's some limit. If you if you make the lights too bright, then it disturbs the thing that you're trying to observe. That's the message of the Heisenberg uncertainty principle. But what I would say is that uh we don't care about both of those things. We don't care about the speed of the particle and the position of the particle. We only care about one thing.
We care about where is my mirror right now. We don't care how fast it's moving.
And so the way to get around the Heisenberg uncertainty principle is to do this thing where you hide hide the noise and we make our measurement by using this idea of quantum entanglement so that we measure one of the variables really well and the other one we measure not at all. So that's the basic trick of getting around Heisenberg uncertainty principle. We're still obeying the uncertainty principle but we're kind of bending the rules a little bit. And one more question like around starting of universe it is said that around one in billion particles survive from destruction by antal and metal collision. How is that?
>> If I knew the answer I would have another Nobel I don't have any Nobel Prize. I would have a Nobel Prize by now. It's a great mystery actually. It seems like from everything we understand, the universe could have been antimatter or it could have been matter or all antimatter and matter could be wiped out and there would be nothing except radiation. And the fact that we all exist is some kind of unexplained phenomenon in the big bang still today.
So, everyone's searching for that answer.
>> Okay. Uh so, we'll take one last question.
>> Uh yeah. [clears throat] Hello.
Uh yeah. So on the on the topic of if uh so we know that gravity as as of now the tensile theory but if if it was a scalar tensile theory if you gravitation would also have another mode of oscillation it should be the tiger.
So can not maybe not lio India but is it is LIGO planning to make uh a interferometer which can detect those modes or can we detect those modes as of now?
um no one is planning [clears throat] um and I think they don't exist but uh there is a theory about that kind of wave and the idea was that if there would be um like this thing that I've been showing you is that the whenever the gravitational wave comes in it's something like I'm stretched like this while my height is decreased it's that kind of a wave it's a stretching shearing kind of thing and the the wave that you're talking about is something where like I could just completely expand like this and contract and how would you detect something like that?
The idea that people had is that we would put a bunch of vibration sensors all over the earth and now people are talking about doing this on the moon because the moon is much more quiet than the earth so far until people go to the moon I guess. But if you measure the vibrations of the moon you should be able to detect this kind of thing that if the entire moon expands and contracts like this the earth itself I was talking about ringing bells and things like that. So my guide Ray Weiss had done this test in 1965 where he put seismic sensors and looked for the earth to to grow in that scalar way that you're talking about. Um so anyway it's possible to do but you need to detect vibrations that are something you know you you use the whole earth as a LIGO kind of detector. uh and so far the estimate is that the scalar part is maybe um 10 to the 25 times smaller than the tensor part at best.
So I think it's I wouldn't say hopeless but that is as hopeless today as this was hopeless 100 years ago maybe. So maybe hopeful.
>> Okay. Uh thank you for this wonderful questions and uh let us uh once again thank uh professor [applause]
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