 Needless to say, all these years, over 150 publications, many students, so all these things perhaps everyone knows. But the things that only those who are familiar with him may know is his interest in movies, literature. And when I say movies, it's not just the Akira Kurosova or Satya Jitre, not just that. But even he's very much knowledgeable about, say, Rohit Shetty's or Karanjova's movies. So his interest spans right from Kurosova to Rohit Shetty. Then that quality I have always noted with the ease with which he can give a lecture about quantum mechanics. He can have the same conversation at a tea shop that is somewhere in a remote place or in some corners of the fort area. I have the opportunity to be with him in such occasions. And he adds this little bit of humor and theatrics, even to rather mundane things and make it interesting. Hope in this topic also we will be able to hear some of those physics as well as some of those interesting touch of humor, art, poetry. And the list goes on. So I welcome Prof. Vijay Singh to give his talk. Thank you. I hope I turn this on. Who is the expert? I am not the expert, but I can try. Am I clearly audible in the back? Okay, that's it. Thank you very much, Mashood, for a very effusive, you know, introduction. So I hope I don't disappoint. And let me try. Okay. And I see only friends here and a couple of, not so friends, but okay. I'll do my best. Okay. Okay. This is basically physics and the city of Mumbai. Okay. So we begin now. Okay. So this most of us, and I'm no exceptions, I've spent a substantial portion of my life in what was once Mumbai and what is now Mumbai. Okay. And I think many of us in this audience have the same background of having spent a substantial portion of their lives in Mumbai. Okay. And basically we are all attached to it and we are all experts. Okay. I mean, we're all experts on Mumbai. So I thought we all have been exposed to, how should I put it, to news about Mumbai. Okay. To poetry about Mumbai. To literature about stories about Mumbai. Okay. But perhaps not to the physics of Mumbai. So I thought I will share some of my thoughts with you and this is supposed to be a light hearted talk. So, and it's supposed to be fully understandable to everybody. Okay. Maybe with the exception of just one formula, which I will use in the end. But so you'll have to excuse me for that. But a hundred years ago, there was actually a shire or a poet who had come from Lucknow and he saw Mumbai. He had come with expectations about Mumbai and he was atop Malabar Hill. Okay. And he saw the glittering lights of marine lines, which is called the Queen's necklace. Okay. And then he was awed by it. And then he went to Hajiali. And this is what he said. This is Hajiali. He saw the crimson sunset at Hajiali. Okay. And he said, Khush Nama Bombay Tuchpe Piro Ka Saya. Khush Nama Bombay Tuchpe Piro Ka Saya. Jaisa Sunatha Tujhe Vaisahin Paya. That is praise or blessed be Bombay. May the saints be benevolent to you, to Bombay. And you have met all my expectations. Okay. So the first site you see is this Minaret. And the first question that comes to us. Yes. Why is there a Minar? So the word Minar comes from the Arabic word Manara, which means basically a lighthouse. Because it acts as a lighthouse. Okay. And it is basically a signaling tower at sea. That's what the Arabic word means. Okay. And why do we have it? We have it because the earth is round. And we have a problem called the horizon problem. That is if the earth was flat, you could see till infinity. Of course, air pollution not being there. Okay. So you could see it to a great distance. But if it's round, then there is a horizon problem. And the first thing we would like to understand is this horizon problem. Okay. So the earth is round. Okay. This is the round earth. This is the radius of the earth. This is the height of the Minara or the Minaret. And then you can see all the way up to the tangent, which is x, the distance x. And this is the right angle triangle. Okay. And you use Pythagoras theorem. It's also Areebert's theorem or whoever's. Okay. And we just use it. And I think this diagram is better. Okay. As I said, this talk is not for you. Okay. R plus h. Okay. R plus h, the whole square minus r square is equal to, I should have called that dx, x square. And what you do is make an approximation. So that's the way you understand most things. If you make an approximation to a very difficult equation such as this. You say r square plus h square. And then this r square minus r square cancels out. And the h is very small. It's only about 20 meters, 30 meters compared to r, which is 6,400 kilometers. So because of that, you make that approximation. You come across a very simple formula, which is 2r into h. Now, what is r? R is the radius of the earth. So 2 times r is 6,400 kilometers. And you take the appropriate, h is in meters, by the way. It's only 20 meters or 50 meters. At the most 100 meters. Okay. Then 2 times r, you just think of a number. Square root of that is just 3.6. You do 3.6. And whatever the h is, you take the square root of that. Okay. So I will take an example right now. And for the hajiali, in fact, if you go atop hajiali, this is what will happen. It is 85 feet tall. So it's 25 meters. So the square root of 25 is very simple. It's just 5. And therefore 5 into 3.6. That's just 18 kilometers. That is how far you can see, provided there is no pollution. Yeah. Please comment. Provided there is no pollution. That's the furthest you can see. I'm really sorry. Should we get some chairs? Because I feel... Okay. Yeah, we'll get... So that's... And if you're a human being, basically your height is about 2 meters. So you take the square root of that and you can barely see about 5 kilometers. Okay. So that is how far you see. And it is the horizon problem. Now I will first continue with the introduction. And then I will come to the main body of the talk. Okay. So but if you don't understand something, please stop me. And sometimes you have more interesting comments to make than I do. So please make those. Okay. So let's begin with a few comparisons. This is Mumbai's history. Okay. In 1661, Catherine Brigandza married King Charles II. And even they had dowry. It's not just the Indians who are the culprits. Even they had dowry. So they have... It was... Bombay was given or Mumbai was given as a dowry by the Portuguese to whom it belonged. And they gave it to England. Okay. It's almost like saying, okay, here it is. And you take this Bombay. Okay. What was happening in England at that time? In England, Robert Boyd had discovered Boyd's law. That is, the pressure is inversely proportional to volume if the temperature is constant. So he had discovered that law. Okay. Then around 1668-69, the British East India Company, which is the biggest multinational corporation ever. Okay. And you should look up the article in The Guardian about it. The biggest multinational corporation. At least seven islands of Mumbai from King Charles. It took the seven islands. It's a... Give it to us. What is happening? In England, their first scientific publication came out. That was in 1665. Okay. And 1687, a very pivotal year for Mumbai. The headquarters of Mumbai shifted from Surat to Mumbai. And in 1687, we all know that we are from physics, that Newton published the Pia. Okay. So what was happening is on one side, we were growing under colonialism. And on the other, the colonialists were doing very well scientifically. Okay. And in order to tell you there is another story. It reminds me about Manhattan. It's the same story there. There was a Dutchman who actually sold Manhattan to England for some 30 guilders or something for about some small amount. And Manhattan didn't even belong to him. It belonged to the Red Indians and he just sold it. So this has been the story of colonialism as far as India is concerned. Okay. So that's a little bit of history there. Let us do the geography. What were these seven islands, by the way? The seven islands that were leased. So they are not to be shown in great detail over here. But these, the seven islands were all of this yellow portion. Okay. And there is at the far end, at the far north is this island of Mumbai. Oh, sorry, Mahim. Okay. Where I spent my boyhood. Okay. And I'm very attached to that place. So Mahim is actually a wonderful place. I have to tell you that it is the most cosmopolitan place it was in the world. Okay. It has one-third Hindus, one-third Muslims and one-third Christians. And among the Muslims, they were also differentiated. There were Shias and Sunais. Then there were Boras. And there were Ismailis. There was Khojas, a smattering of Ahmadiyas. And what have you. Okay. And among the Hindus, of course, I mean, we are very diverse. I mean, you know, there was the Chandrasee Kais Prabhu and the Patari Prabhu. And then there was the Chitrapura Saraswats and the Gaud Saraswats. And depending on whom you talk to, the other guy was inferior to them. I mean, that's, I mean, you know, and it was always like that. We always looked down on the others. Okay. So I grew up there. So I couldn't resist telling you sharing this thing about. It basically reflects all our boyhood and our nostalgia and our love for the city. Okay. And if you can see this, this is actually north-south. Okay. This is the southern tip. This is the northern tip. And you have Mumbai city, which is the island city. It's called, it's about 70 kilometers square. And the rest of it is about 370 kilometers square. Okay. The suburban part, where we all live now, and most of us live there, except unless you live in the TIFR colony. Okay. Then of course you live right here. Okay. And the population is, you know, I kept, I kept losing track as I kept studying this thing for 16 million and then become 18 million and perhaps it's 20 right now. And the population density is enormously high. 40,000 or more per square kilometer. Okay. So that's the geography. But you can see it's north-south. And the way physicists try to understand this is by saying it has a metric. The road map, the roads of Mumbai follow what is called the Manhattan metric. So I have to tell you what is a Manhattan metric. Okay. So the Manhattan metric is something like that. Of course it's, it's not Manhattan, but this is Manhattan. Okay. Manhattan is like Mumbai. Of course I told you the history. The history is also similar to Mumbai. It was gifted to England. And it is south and this is north and this is central park. And there are avenues which run north to south. And there is a large number of streets which run east to west. But the streets are shorter. The avenues are very long. Okay. That's the way it works for Manhattan. Okay. And this is, this is right angle roads. It's called the Manhattan metric. And most island cities tend to have the Manhattan metric. Okay. Even if you look at Bombay or Mumbai. Okay. It is the same. There was the Muhammad Ali road which starts on one side and goes all the way down. And of course you give it different names as it goes. Baba Saiman Betkar, V. N. Purao. And then it's just nothing but the Muhammad Ali road. Okay. On the other side, there was something called the Lady Jamshadji road, which also ran a long distance. But now we give it different names depending on whom we want to please. Okay. So as opposed to that, there's a Moscow metric. The Moscow metric basically is radial. It starts off from the Kremlin and it goes and spreads like this. Okay. So Mumbai is the Manhattan metric. Delhi from Connaught Place has the Moscow metric. Okay. So as a first approximation to the road map, you think of it either as a Manhattan metric or a, or as a, how should I put it? Or as a Moscow metric. Okay. But I have to tell you one thing now. This work that we did was done in the Olympiad cell. And with each of the people who worked with me, I mean although they were not physics people, we did some physics work. So this particular work was done with the help of Sana. She is right here. So she did, it's a collaborative work and our mutual love for Mumbai made us do this. Okay. And there's a similar piece of work which I hope I can present sometime that I did with Suchita and the third one which I did with Ranjana. So I have to acknowledge. Thank you. Okay. So now coming to the main body of the talk. Okay. If you have been in Mumbai for about five years, you know 10 years or 20 years, there are some pivotal experiences. Okay. There are some things that you always have. You know, I'll share with you and you will also come back and share something, a story with me. Okay. So there are four or five of them that I would like to address and I will make some comments about them. Okay. Which are the ones? Mumbai rains. Okay. I mean all of us have some stories to share and you get wet at least once, every monsoon in spite of your precautions. Okay. So there's just a picture of the Mumbai rains. Okay. And you know, I always listen. If it does nothing to, you know, if you want to make small talk, I mean there's always a rain and there's something else which I will tell you and if you have lost, there are at least five topics and you can start a conversation with that in Mumbai. Okay. One of them of course is the weather and particularly the rainy season. Will it rain today? Will it not rain today? You know, what a bad day or I lost my umbrella or something like that. Something. Okay. So this is, I think there was a very, how should I say, a catastrophic rainfall when I first joined here, I think it happened in the same year or the next year. We had a very heavy rains for about six or seven hours and that actually flooded Mumbai. Okay. And there were stories about how people were trapped inside the car and they were not able to push out. Okay. Because the electronic system failed, the windows were locked, the windows were closed and they just couldn't push themselves out. Now the question is, is it true or is it not true? Okay. So we can analyze it. Okay. That they were really not able to push out. So how do we understand this? We understand it by saying, okay, my weight or my mass is about 80 kg at the most, it's 100 kg. And I can exert a force which is 10 times that. The 10 times because of gravity. G is the gravitational constant. So the force I can exert is 100 into 10. That is 1000 Newtons is what I can exert from inside. What can be exerted from the outside? It would surprise you. From the outside, even a very conservative estimate will tell you that it is 5000 Newtons. And here is the calculation. As I said, there are only two equations I will show you. This is one of them. And I couldn't avoid doing it. Basically, there is a pressure on the door. So if there is a lot of flood, if there is a lot of water, the water exerts pressure on the door. Now what kind of a pressure does it exert? It exerts a pressure which is given by a formula. The formula is rho into G into H. Rho is the density of water, which is 1000. G is the, G is 10. Forget whatever it is. And H is the height of the water. Let us put it as 1 meter. So if you take 1000 into 10, it is 10,000 already. And the water is at least 1 meter up there, outside, outside. So it's about 5000 Newtons. 5000 Pascal say. Thank you very much. So it's about 5000 Pascal. Now what is force? Force is pressure into area. Most people have difficulty. See whenever you introduce a physics quantity, it is incumbent on you to explain why you are introducing. I mean, I'm not supposing I talk about epistemology. What is the meaning of this term? Why do you use this big term or something epistemology? So when you talk about pressure, why is pressure so important? Pressure is more important than force at times. See for example, when you take a syringe needle and you poke yourself with it, when the doctor pokes you with it, it's a very small force. It's the force of only one Newton. But the area is so small, so minuscule, that force divided by area becomes very large and therefore it punctures your skin. We have all been in circuses where we see people demonstrating how an elephant can stand on your chest and another person is not killed. Nothing happens to him. The rib cage, the rib bone doesn't break. That is also very simple. That is because what he does, is the plank on top. The plank makes it a large area. So even though the force is large, the pressure is large at one point. It is divided over the area. So the pressure is very low overall. So that is what is happening. So basically the force is nothing but pressure into the area and that is about 5,000 Newtons. So area is about one meter square. Let us say the outside door of the car. It is a very conservative area. It is more than one meter square. But let us call it one meter square. It is more like two into two. It is four meters square. So it is 5,000 Newtons. And all that you can exert from the inside is about 1,000 Newtons. So you are trapped. So it is plausible. The stories that you heard is a plausible story. Maybe it never happened. But it is a plausible story. But it is quite lethal at times. The other topic is of course the Mumbai trains. We all know about the trains. I mean trains is the lifeline of Mumbai. Lifeline it is. And let me tell you some history about it. It started in 1853. It started with the 14 port steam engine. It started from, I think some of us are from Tane. It travels from CST to Tane in about one hour and 15 minutes. Making two stops along the way. Cyane and Baigala. That was a long time ago. But how long did it take? One hour and 15 minutes. Just one hour and 15 minutes. How long does it take now? It takes one hour. That is a great improvement. About one minute every 10 years is what we have improved on. So it stops at 18 stations. So basically I thought I will give you the school statistics. But I will give you a grim statistics also. Lifeline it is. But the Mumbai local trains are also life takers. It is the artery. Mumbai local is the artery. But the artery is bleeding. This is a small calculation. If you have been here for 20 years you would know somebody who has gone because of the Mumbai local. And I know of three people. One of them several of us know here but I will not name him. What is the speed of a fast train? It is about 90 kilometers per hour. 25 meters per second. And supposing you are trapped. Say in front of an approaching fast train. And somehow you cannot move. Something has happened to you. You have fallen down and you cannot move. The question is can you survive? If you are 100 meters away. Now I want an answer. 100 meters yes or no? Give me any answer. You can either be right or wrong. Actually the answer should be no. What about 200 meters? Yes or no? Come on. 300 meters? Yes? Yes or no? 400 meters? Yes. Very good. 500 meters. Definitely yes. The answer is no. The answer is no. Because the maximum de-acceleration that a train can do is minus 0.5 meters per second square. If it did anything more than that the train would jump. And then the train driver would be killing a lot more people than this one person is trying to save. So this is the maximum. It is a number that people do not quite appreciate. It is very very small. And then you use a simple formula. And in this formula all that this is the final velocity which has to be 0. This is the initial velocity which is 25. I said it is 25 meters per second which is 90 kilometers per hour. It is a real fast train. And the acceleration as I said is minus 0.5. So if I take minus 0.5 and multiply by 2 I get 1. And if I take this 25 and square it I get 625. And therefore the distance is 625 meters. So even if you are half a kilometer ahead the person the driver in the fast train cannot stop. And often you are less. And you haven't even considered the reaction time. The driver has to see and then stop that reaction time could be 2 seconds. In that time it already traveled 50 kilometers. Because it is moving at 25 meters per second 25 into 2 is 50 so you get 50 meters. So 675. So never ever cross the railway track. Yes. I am saying you are trapped there. You can't move. That's true. You can do that calculation. And that's usually shown in movies. You know if you see in most of the movies by Salman Khan I mean he is just crossing in no time at all. Right? So I will tell you another thing. The real reason it happens I think is probably psychological. There are three reasons and let me tell you. One is that if you do an activity not right. Then you get used to it. It becomes a habit and you think you can do it. Supposing you have done it for 100 days by the law of induction you can do it for the 100 and one day. So that is one habit. The number two thing is when the trains I mean this has been noticed already when they blow the horn it is so loud that instead of flight you freeze. So it's just flight of you tend to freeze when you hear that loud sound. Unsuspectingly. And the third thing is actually a very interesting psychology. What happens is if you have a very long object and if much longer than you and if it is moving slowly or it's moving very fast you tend to think that it is moving slowly. That is because you calculate its speed with respect to its length. It's a psychological thing. It's a biological thing. So it's moving fast but you think it is moving slowly. That is why you have these phrases like an elephant lumbers along but an elephant can catch you in no time and maul you. And that is why you have this phrase an ant is scurrying along. You have used the word scurrying because it's running or something. Actually it's very slow but compared to its length it is very fast. So that is why it's happening. So a big train is coming and it's moving fast and you cannot. There is another one which I should tell you about. It's also very interesting. I have to tell you a little bit about a principle called Bernoulli's principle. The way I explain it to students is that when the stock ends everybody will make for the door. So near the door there is a lot of pressure the velocity decreases. Nobody can go in and we start jostling over here. And once you come out the canteen. So similarly pressure is large, velocity is low and vice versa. So plane flies one of the reasons, I mean they are not the only one is that the way it is designed is that most of the air flows up. So the pressure is low there and the air below is moving slowly below it so the pressure is high so it's actually lifting the plane. High pressure below above. The same thing happens on railway tracks. You are asked not to stand close to a fast train. The reason is because the fast train is dragging. The fast train is dragging the air because it is dragging the air the velocity is large the pressure is low. Behind you the air is stationary so it's pushing you inside. So I used to have an old Maharashtrian lady who said don't go near the railway track because there is a booth it's called railway line booth. Why is it a booth? She thought the spirits of the people who have been killed by railway trains are restless and they want you. So when you go there they just drag you inside. So it's called railway line booth. Booth or otherwise but normally your booths don't go near the railway track whichever one you want to accept it is fine but you don't go near the railway track and this is a very dangerous activity. Third problem always a matter of conversation housing problem we are always like how much is your flat the first question they ask be you own it yes how much is it if you don't own it how much do you pay and then everybody brother is an expert on the real estate of Mumbai and you can see how the real estates are these are the real estates of Mumbai we all face a housing problem because we are all ordinary people ordinary mortals and that is what happens how do we deal with it how do we try to understand the housing problem population density is very high 40,000 people per square kilometer so you deal with it by understanding something called surface to volume somehow you have to increase the surface and one way to understand this problem but not the housing problem is to see this church it's a church from Mumbai I think it's Michael's church in Mahim so you see this church it has large windows why does it have large windows because the surface area I think the light is from the windows supposing it was all covered or something like that then there would be no light coming in so you try to increase the surface area from which you get the nutrition in this case nutrition is light so if you look at many of the Hindu temples it's all very dark because we didn't think of this as something like we should put windows in our in our mandir or something like that sanctum sanctorum are all very dark or something like that so even the modern malls have this so called top thing which gets you light so surface to volume is a very important law and it cuts across anything I mean if you cannot explain this is the one law which even beats Newton's second law because this one law works in many places it also works as far as the housing problem let me show you an example you see this is from Dharavi this lady is actually very interested very intelligent I would say because she is making pappad but if she just put it on a flat she could only make 10 pappad but she is putting it on a curved surface she is going into the third dimension so going to the third dimension is giving her extra mileage an extra surface to put it on so she has surface to volume is increased so she is putting more pappad and she is actually making a little bit more money than her neighbour who doesn't think of this idea everywhere is a surface going into the third dimension double decker bus look at our trains there are triple decker trains look at these people I am not recommending it but I can see why this happens understand something is not to condone it but I can understand why they are doing that because they can't fit in here all our skyscrapers we go into the third dimension in fact the Mumbai skyline is like any other skyline similar port all the skylines are similar and I have done a small fractal calculation for this but you can calculate the fractal dimension of the skyline of most cities surface to volume here also these are our so called modern airports how do they increase the surface by actually putting a lot of air jetties outside so they can fit more planes area cannot increase but by putting these jetties you have increased the number of places for these planes to park so this is almost like the villa of the small intestine or like the modern baths tower where you actually put out small which drives you better you increase the surface area that's what I have to say about the housing problem I have many other things but this is I will leave it with this let's go to the ceiling now ceiling is not a very common topic we just built it in the last 10 years but there is something about the ceiling and I will have somebody assist me in this where it's very interesting if you come from the Bangalore side you can see the ceiling the ceiling is this double-stayed cable it's like cable on this side and on the other side also there are these cables which fan out at least about 40-50 of them but if you come from the Bangalore side next time you come you watch this next time you come there will be a pattern of these fans and there will be another pattern behind it of these same fans and as you go you will see a very interesting pattern emerging a wavy pattern that emerges those are called moire patterns first I will show them to you this is the kind of pattern you will see you will get these things like this these moire patterns when I first saw it I was very thrilled because I had not seen it before in a real situation in Mumbai but this is called moire patterns let me just share something with you can you help me with this someone has to help me you can also do it and play around with this moire patterns and you can give it back here I don't think this will work this at this I will give you more so they can all see this then this one also take this one also this is it I will show you something else where can you get moire patterns you can get moire patterns provided you travel in second class not first class and provided that is a challenge provided you are at these various intersections at times in a taxi or in an auto these small kids trying to sell you wherever I go I always buy one because you can get all kinds of running pictures with these moire patterns you see what it is you must have all so next time please buy it you can understand what a moire pattern is give one on this side please return all of this in the end so in 1890s if you remember I mean this is a gift this is a question at the end whoever answers will get a moire pattern from me so that is what I will do oh well I am doing alright with time I think so the story is in 1890s they didn't have movies in those days so the way they made movies was by making story books with moire patterns so you have Jack and the beanstalk moving around and the beanstalk growing and so on and so forth and little red riding hoodrow walking and the wolf eating her not her but her so all these moire patterns are there but now they went out of fashion as soon as what is called chalchitra or movies came but there is something I found very interesting that new 2000 rupees and 5000 500 rupees notes they have interesting patterns and for a while I wondered what are these patterns then I zeroxed one which is illegal I made another one which is also illegal so two illegal acts and then you move one on top of the other and that is how I make out if my 100 5000 rupees note is fake or not and then I found that interestingly even the German currency now actually does moire patterns to find out if it is forgery or not somehow the person with whom I shared this he took away my this fake 500 rupees note so this is not very good 2000 rupees note so it is not very good but if you try hard you can see a moire pattern you do not look at the main thing you do not look at Gandhiji look at those intricate patterns put one on top of each other I blew it up and this is kirtse chitra in the Olympiad lab I got it all done and then you just move it around and you will get that so moire patterns are there the second class compartments you can get it intersections you can get it you see here there is a moire pattern again take two grids move them against each other why are they used? they are used to find out small imperfections that is why the moire pattern is used here it is here and basically it is the analog of what is called interference phenomena which establish the wave nature of light so that is moire patterns right here so that is about the ceiling now let me tell you about now this is not the main thing people do not talk about it but we talk about some scientific institutions of Mumbai so since I have 15 minutes can I take 10 minutes ok so scientific institutions of Mumbai and Mumbai is associated with many great scientific institutions and this is probably the greatest ok so this is the other observatory in 1826 it maintains a continuous geomagnetic record starting from 1850s for 150 years it is actually a world class institution in that world regarded for the maintenance of geomagnetic record what they do is they measure the magnetic field but the magnetic field we know is 3.1 in whatever unit it is called Gauss it is 3.1 Gauss we are interested in the variation the diurnal variation the seasonal variation if there is a sunstorm what happens to it so they actually measure it and one of the greatest sunstorms took place in 1857 when we had our independence war it was a very big and it was called a huge storm came so called storm came and all throughout the earth and they have that record too all their instruments went haywire at that time ok so this is a magnetic observatory it was in Kulaba but it had great people in it and I have to tell you one story which is scientifically related it has to do with trams and this Kulaba observatory how many people know this story and I am going to tell you a very interesting story you know trams were introduced in 1874 ok in Mumbai I don't know when they were introduced in Calcutta and they were drawn by horses you can see these horses where did mine go I lost somehow so after that around 1900 they decided to do away with horses and they wanted to make electric trams to run from Parel all the way to Kulaba but then the director of the Kulaba observatory stood up his name was a parsley gentleman because Nana Bhai moves and Nana Bhai moves said I will not allow this tram because the trams will use electric current the electric current will produce a small magnetic field it will interfere with my observations ok so here it is but first I will show you the trams these are all these interesting double-decker trams are also there I don't know some of us were I have been on trams in Mumbai it used to run up to King Circle then ok and you know there is a terminus in King Circle so it would go around and as small boys you would just jump on it and go all the way around and the conductor would try to get us off you know so this is some brief history of the trams ok it is basically double-decker and it stopped in 64 so if you were born after 64 you never saw it you never saw these trams in Mumbai at least in Calcutta of course they are still around ok so what was the controversy so Mr. Nana Bhai said I will not allow it here is a small calculation which you may or may not be interested in if the current is large the magnetic field is large the current is proportional to the magnetic field and taking the distance r r is the distance between the current and the observatory so I am taking that to be 100 meters I get a quantity like 0.0004 gauss whereas the earth's magnetic field is 3.1 gauss but the measurements are of that level even in those days the measurements went up to this now they go up to nano tesla or something but they go even 3 zeros further so it is 0.30 now it goes up to 6 zeros but in those days the measurements were up to this order Nana Bhai moosa was very annoyed and he said I will not allow it and he stood his ground from 1900 to 1907 he did not allow the trams I wish some of our present day directors would stand up like that in piety or whatever instead of keeling over every time the government coughs and the government sneezes and they get a cold so this is what happened ok what did he do? he said wait I will shift my observatory to a similar isoclinic line in alibag and build one there until it is done don't bring the trams it took about 7 years to build it I think I have a picture of that alibag one and I think you have been to alibag Raul is from there so this is an alibag observatory a great story about the alibag observatory was that every brick was magnetically tested to be neutral because if it had some iron in it it would have some magnetism in it and it would be something which would destroy which would interfere with its measurements so some of you should go to alibag and see this it might be a nice experience another one is the Bombay Natural History Society another great institution the bomb started in 1883 few of us know from 1912 to 1924 they carried out the first citizen science initiative ever and the largest I think for 12 years they wrote to their how should I put it they are members of a voluntary organization purely voluntary they wrote to them across India to say we want to collect mammalian species and they collected 5000 of them 5000 specimens 5000 specimens and 47 new species several were new and for 12 years they did this effort it is usually associated with polyanthology or bird watching but they have done some great work in the other fields also and this 1912 to 1924 a great project I would like to talk about it sometime how they carried it out another one of course is VJTI the chairman the present chairman of VJTI is a product of VJTI Shekhar Basu is it yes Afghan Institute the others you all know about TMC Royal Institute of Science where some of us may have studied that is in Colaba TIFR, BRC IIT and of course the Indian Institute of Geomagnetism which is now shifted to Panvel there are two recent ones you probably don't know about I will tell you about them now this is the Geomological Institute of India founded in 18 1971 so I made a visit there they have equipment which would rival even TIFR the kind of equipment for diamond testing that they have they run courses which are basically which actually equip you to do diamond testing geomological courses, jewelry making courses you can all register for it on the side it is what is called long distance off campus course and it is actually quite interesting you can learn a lot about gemology all the gems are over here this is what is called Mukthika that is pearl and this is ruby and this is blue sapphire and so on and so forth this is one of them and their lab is in Sukhsagar in Chopati on the fourth floor and actually believe me I have been there so as Sanna and so as Ranjana I have taken my PAPAs there also so they have seen this and that is the one time they got to test to actually hold a diamond which is this big or this small and one after another at least 30-40 diamonds we all saw them at least that was enough what is it called that is called the Indian Women's Science Association there is another one there is probably one of the later so this is another one and I think several of our people are there I think Mrs. Mahajan Professor Mahajan is there I think Chitra was there so this is the institutions and since I have 5 more you will have to give me 5 more minutes this is Bombay and Bollywood Bombay and Bollywood is a love hate relationship all these guys are there all these scenes that you see in movies which are all bunkum I will not even bother to analyze them you cannot do any of them here is a guy he is I do not know who is he the car is moving this way he is actually going in the backward direction he is getting out in the backward only yesterday in Thane two days in newspapers day before yesterday a person tried to do the same he fell backwards he broke his head and he died I do not even bother to analyze all this because it is also off the wall to do the physics and there are sites which do it by the way I would rather do something which is more interesting and let me share it with you let us say here is from the Raj Kapoor scene you see this moonlight so I wanted to capture this moonlight with my equations but let me just play it for you that scene it is a 20 second scene and I will tell you which scene it is oh no very beautifully done I will just end on that note of that note you know you do not know what is going on after that but ok that is it and then they leave it at that so I thought I would try to write some equations for it and I wrote it so I will not bore you with it but the thing is actually quite the model is simple what is it? oh I expand it I need to expand this so what the model I can say the derivation I will not talk about so here is the lake and there is waves in the lake so basically the maximum angle that it makes from which the moon can reflect is say alpha say 10 degrees or something I said it is like alpha is about 10 degrees it is on both sides the wave reflects like that so it is about 10 degrees here the moon comes and it reflects here where the photographer is and then you actually calculate how big how much is the shadow or the reflection how much is the reflection like so you do not have to focus on anything else just focus on the denominator here there is something called theta and 2 alpha so now alpha is very small it is a light breeze moving it is not like a big hurricane moving over the lake so it is about 10 degrees or 20 degrees and if the moon is also low if the moon is also low on the horizon it is also about 20 degrees you are bound to get a 0 minus 0 in the denominator 20 minus 20 say or 10 minus 10 or 0.1 minus 0.1 so you are bound to get a 0 in the denominator so you will get a very long reflection and what you have here AB AB is this distance how long is that reflection so I wanted to calculate that just to capture that one scene I failed I mean I just could not do it all that I got was this insight that if the moon is low and something that you have seen if you have been to the sea shore you have seen it if the sun is low and you are here you will see a very long reflection of the sun so I failed so I just wanted to tell you that but there is another scene again from Raj Kapoor's Sri Charsobis the wonderful scene it is very small but look at some other reflections this one for example the reflection of this thing it is very long so it captures my equations captures this thing to some extent qualitatively I am not saying quantitatively but qualitatively so I sort of try to work around this there is another one which you all know about it is from the Mughalism scene which are made of Belgian classes it was made from Ferozabad K. Asif did it and you will not believe it I am told I am not sure he is right he destroyed the whole thing but nobody else could make it but the Shish Mahal you will find in several places in India you will find it in Jaipur it is in Lahore it is one place in Maharashtra also I forget where there is a tiny scene what the scene is Bajira is standing here there is a mirror this guy is pointing to the mirror there is one reflector here there is another reflector here and it gets reflected on this screen it is called the Aayna Mahal scene and it is a very famous because in the end I think the protagonist who is standing over here she burns it that can be captured in fact I am planning to buy some mirror so that when I do another talk I will actually demonstrate this so here is the object here is Mr. Bajira and this is how it is there is a concave mirror there is a plane mirror here and you can capture it just a concave mirror and a plane mirror may be able to capture it but perhaps Rajesh has a better idea so with this I think I have just one light hearted comment about because beaches and newbies I have to put it together I do not have much time for that so I thought I will do this one you can see this panipuri and these are two actors who are having this panipuri what about the panipuri what is the volume of a panipuri so we got into the volume business can you guess we bought a lot of panipuri actually we did it in the Olympiad in the Olympiad office we did all this we bought a lot of panipuri and measured it the average is about 15 cc if you take 6 of it it is like 90 cc 100 cc is what it is it is excellent because excellent why there is my solution to juvenile diarrhea because it has got salt in it it has got sugar in it for which some Bangladesh is getting almost a Nobel prize I should be getting a Nobel prize so proposing this as a solution for juvenile diarrhea I have panipuri you have clean water you have clean water you have clean water ok so thank you very much yes oh no I have not done it I have not done it I have not done this but you know you can stand between tracks and still survive it is not recommended yes they shouldn't it is actually a very dangerous activity even for them yes with what you say that in Estau the note that note is actually fake perhaps yes the german ones are doing it that way so why is it hard to get a genuine note which doesn't reproduce does the reproduction of the why can't the counterfeit reproduce it but even a small imperfection would do it would give you a problem see the point is it has to be exactly those patterns and those patterns are very intricate on these 500 and 1000 rupees 2000 rupee notes they are very intricate now I want to counterfeit it I will make some mistake if I make some mistake yes so what you do is you put one behind the other or you know I don't think they do it this way they don't do that in the banks but this would be one way that they would finally detect a very good fake as a normal rule it's hard to see it as a normal thing but you can do it in fact the german currency is now using moiré patterns they test it out against a similar thing and there is a light from behind they have a counterfeit tester and they test it out against that to see if there is a wavy pattern coming that is what they do yes all lines so usually in big nodes they print it so the mechanism of making their own is so you cannot actually make a fake moiré moiré so it's a way of making the fake yes and that screw it against so it is one way to detect fake currency that is all remember yes no I have I have done a few you know the traffic what is called a traffic wave problem there is something called a traffic wave problem to come to an intersection with what speed should you come that you can move slowly ok now I have done some modeling but I cannot present it I thought maybe in the stock I cannot present it the traffic problem is very very bad now it is a a nightmare you know it's not a traffic jam it's called a traffic snarl you know that's the word they use so that's what yeah yeah there is also about a Dabawala thing there are several such ideas I have not analyzed them because they they do a perfect job apparently I think outsiders talk about the Dabawala more than Mumbai curse too iconic of the city see no Dabawala how they do how they do this management yes it's a good thing to look into what are the others traffic what else Mumbai beaches also one could do some analysis you know how the plastic gets pollution pollution is a big thing and we have worked we are trying to write up something on that noise pollution air pollution people get out of the train stand in light for rickshaw stand in light for everything through most yes I guess we are done about here everyone is invited to see you thank you