Good morning. I'm Kristen Velletti and welcome to Newsdesk on SiliconANGLE TV for Monday, June 10, 2013. The whistleblower behind the Prism Program and NSA surveillance revelations has revealed himself. Join us now to share more as this controversial story unfolds is SiliconANGLE contributing editor, John Castoreto. Hi, John. Thanks for joining us once again. Thank you. Friday, we reported that six major tech companies were denying involvement with the controversial government prism program. Today we have information on the individual who is responsible for what is now being called one of the most significant leaks in U.S. political history. So, John, for those who haven't been keeping up, give us a quick review of the information that was leaked and why this is so controversial. Well, last week the world became aware of the data harvesting operations that are being conducted by the NSA. There were many of us that thought it existed or thought something like it existed. Some of us had even heard about it, but, you know, and certainly there were indications that some large-scale operations were underway by the government, but, you know, it really started to emerge as proof, had a name, we had a program, we had slides and a deck and things like that that came out, you know, that really put some substance around this that this NSA program existed. And in doing so, they basically described how they had this unfettered access to private citizens online accounts from Facebook, Google, Microsoft, the list goes on, all the big ones. And in order to do so, what they were constructing was this wide-spectrum data operation where they were doing analysis and intelligence gathering. You know, it's important to note, however, that some of the controversy surrounding this is really, you know, this whole notion of privacy versus security. And, you know, although it's design really was an intent on spying on individual citizens, a lot of people are concerned about that notion nonetheless. Have any of these accused tech companies spoken out more about Prism or are they still denying involvement at this time? Well, officially they are still denying involvement and, you know, that indicates what is probably a premeditated protocol in the event that such knowledge of this had gotten out. It's interesting, however, if you look at some of the statements from the president from different people that we've heard, the director of National Intelligence James Clapper, he blasted the information leaks, but, you know, he also stated that these programs are legal, limited in scope and necessary to detect these terrorist threats. The government hasn't denied it themselves and they're actually defending it as something that's necessary. Now, 29-year-old Edward Snowden is the individual who has named himself as responsible for the leaked information regarding the Prism program. What can you tell us about Snowden? Who is he? How did he have access to this information? Well, yeah, that's pretty interesting. It's something that we see a lot in the world of security. Edward Snowden was a former technical assistant for the CIA, currently an employee, a contractor, if you will, of these defense contractors, Booz Allen Hamilton, Dell. He'd been working at the NSA for the last four years and had been an employee of these various outside contractors, including Dell and Booz Allen. Now, after disclosing these numerous top-secret documents to the public, Snowden made the decision not to opt for the protection of anonymity. Why did he choose to reveal himself, John? Well, you know, he basically chose to reveal himself because he felt what he's saying officially is that he had no intention of hiding because he says that he has done nothing wrong. So he really wanted to be public about it and I think he feels that he's insulated from some of the things that he felt could happen to him by just coming out and saying, hey, it was me. In a statement about the life that he's leaving behind, Snowden said, I'm willing to sacrifice all of it because I can't in good conscience allow the U.S. government to destroy privacy, internet freedom and basic liberties for people around the world with this massive surveillance machine they're secretly building. John, how do you think Snowden's message is going to be received? Well, I believe it has a populist appeal and there's going to be many people from across the spectrum, politically, socially, people that are on the side of electronic freedom and so on, and they're likely to be accepting of it. As far as some of those questions are out there, this is something that has to be metered with some reality as well. The NSA ostensibly launched this tool to help protect our country. That's a big question of this whole freedom versus security argument and one that we're going to be dealing with for a long time. Essentially, the bottom line is that privacy is dead. What kind of consequences does Snowden face for going public and how is the government responding to his actions? Well, he faces a world of trouble. I was at the defense contractor at one point. We all take an oath. I think mine expires when I'm 112. It'll be a long time before I can disclose some of the things that I did, but there's a lot of rumors out there. There's talk today that this may even be an act of espionage, which of course, against this country, carries some significant ramifications. So we'll hear more in the coming days as far as what the government's official responses to what Snowden has done. I think we've heard a little bit from Clapper as far as the consequence, the great consequence of what's happened and what's been leaked and what it affects. But there's a lot of rumors out there. We're going to hear a lot of things that are unsubstantiated and we can't really verify very quickly. I think in the big picture, this will eventually get to like a Bradley Manning situation where we have a very public trial and we bring all these things out or at least some big discussions around the security of this. Now where is Snowden now and what are his plans? Well, he's holed up in a hotel in Hong Kong and he's remained there since releasing the documents. He actually left Hawaii, jetted out of there in anticipation of knowing when this was all going to be released. The word is that he chose the city because he felt that they had a spirited commitment to free speech and the right of political dissent. That's a quote. But here's one of the things Hong Kong is under Chinese influence. Although, yes, it is more or less independent. If you look at the big picture, a lot of people feel that this could be some type of flight to China. He's certainly not coming back here and extradition would be something that politically would be difficult. There would be all kinds of issues with all kinds of political ramifications and economic and just a whole bunch of things would really tie into. It's hard to say. I think that most people feel that he's going to definitely remain in China and not coming back or remain in Hong Kong and possibly going to China and seek protection in there. Do you think Snowden's choice to go public could benefit him anyway? Is there any chance it will make it more difficult for the government to charge him because of that? Well, I think he has hopes that the publicity will give him some protections. In other words, the people will cry out because they would have found him sooner or later. He also said that he felt that it would make it harder for them to get dirty. I think implying that they would just take him out somehow. If it was very public, if everybody knew who he was and all of a sudden he disappeared, this would be something that would be very public if he disappeared. I think that gives him some solace in terms of being able to protect himself. Do you think Snowden's whistleblowing is going to have any sort of effect on government actions? Is he going to see the change that he's hoping for? It's doubtful. As I said, there's a lot to wrangle with here as a society, as a country. The government of course feels that this is something that was legal and necessary. Private citizens are going to probably more gravitate to the side of them. They feel that their legal rights are slipping away. All the different things from privacy to search and seizure, the First Amendment, and so on, all able to be reached into and looked at by the government and different agencies. There's been scandals with the IRS and being pointed out for having individual perspectives on things. As we saw with the naked X-ray scanners, the public outrage can have some effect. Those have now been removed from these airports. Although the government never really admitted any overreach or wrongdoing in putting those out there, they have retracted these machines. They're controversial. I don't think that will happen here, though. This is just too well-rooted. There's too much intelligence that can be gained out of this. This is not likely to go away. I want to point out, though, that as far as the privacy issue goes, Jeff Kelly's piece on accumulo and protecting your anonymity in a way of being specific about these analytics and making these things possible. It's something to consider. They're not really looking at individuals. They're looking at patterns and then going down and getting down to that detailed level. There's just a lot of information to deal with. There's a lot of angles on this, political, technical. It's just a lot of things to look at, and we're going to be watching this for a long time to come. Well, regardless of the lasting effects, it's definitely brought this issue to light and definitely stirring up the conversation, which is an important one to have. So thank you so much for taking the time with us, John. Thank you. And on the way, Google looks to add to its mapping capabilities and a high-speed thumb drive that puts all others to shame. These stories and more are in your SiliconANGLE Daily Roundup. That's next here on Newsdesk.


Mr. Chair, Ministers, senior government officials, ITU elected officials, fellow participants. First of all, let me express Canada's deep appreciation and gratitude to the government of Romania for hosting this plenipotentiary conference in this beautiful city and in this magnificent palace. Over many years at the ITU, we have witnessed Romania's great contribution to the work of the Union. More recently, Mr. President, we have you as your great team and you have participated with diligence and success at a multitude of regional organizations of telecommunications like ours in the Americas. The Inter-American Commission of Telecommunications, Citel. You have paved a very positive and consensus-based way forward to this plenipotentiary conference, provided valuable advice and views, and generated an environment of friendship and open communication for which we are very grateful. Let me pause here to remind everyone that we recently participated in the World Telecommunication Development Conference held in Kigali, Rwanda. I would like to express our sincere gratitude and congratulations to the government of Rwanda and particularly to Minister Pauline Gabire for having hosted such a successful conference, the first ITU Development Conference on the African continent. I would also like to share our congratulations to the government of Rwanda and to the UIT Development Bureau for the global summit of youth organized in the initiative of Generation Connect, which took place just before the global conference on the development of telecommunications. To say that the participants were a very stimulating and energetic event that will look more than 450 years old in the Kigali kingdom and more than 4,000 participants from all over the world. To the youth envoys that were in Kigali and to those listening today, Canada congratulates you. Rest assured that we will continue supporting your efforts and your rights for a meaningful engagement in the decision-making processes on your digital future. The digital future is now and you have a meaningful role in shaping it. Certainly, youth require and we hope for them a world of peace and so in the context of the war in Ukraine we must reaffirm our commitment to the UN Charter. Mr. Chair, in the next three weeks that await us, allow me to highlight one of the biggest priorities of Canada in a fundamental role that will play this conference of full potential in the orientation of the next four years of the UIT. Whether on radio communication, telecommunications standardization or development matters, our collective priority at the ITU should continue to be on connecting the unconnected, bridging the digital divide, including the gender divide, empowering youth, all with a particular emphasis on the needs of developing and least developed countries. As we discussed during the ministerial round table on building a better future for all held in these beautiful premises on September 25th and best reflected by the Bucharest declaration, connectivity is at the center of sustainable digital transformation. We need to redouble our efforts to deliver prompt and tangible results. We need to take additional steps to ensure no one is left behind. As a key enabler of innovation, competitiveness and economic and social prosperity, digitalization needs to be premised by fundamental principles of universality, equity, affordability and trust and confidence in the use of ICTs. Tout cela est possible si nous unissons nos forces celles du secteur privé, de la société civile et du monde universitaire et si nous adoptons des cadres réglementaires qui favorisent la concurrence, l'investissement, l'esprit d'entreprise et l'innovation. These principles should guide policymakers, citizens, businesses and civil society organizations, all in the understanding that our telecommunication and ICT future lies not with state-centric, top-down decisions, but with a collective, multi-stakeholder decision-making process that includes the voices of all, including youth and particularly women. Mr. Chair, malgré tous nos affaires et nos réussites collectives, 2,7 milliards de personnes ne sont toujours pas connectées. Le plus part se trouve dans le pays en développement et le pays le moins avancé et la majorité des femmes. C'est tout simplement inacceptable. Nous devons prendre les maisons nécessaires pour qu'à l'issue de cette conférence de plein de potentiaires nous rentrions tous chez nous avec un esprit de consensus réneval et le sentiment qu'on a venu a beaucoup plus rapide ce profil à l'horizon. You can count on Canada's ongoing support. Merci. Thank you.


What's going on here? We had two bags of grass, 75 pellets of mescaline, five sheets of high-powered blotter acid, salt shaker full of cocaine, a whole galaxy of multicolored uppers, downers, screamers, and loafers.  Apparently this won't work either. So hey, look at that. Come on, you got that? Boom. Alrighty, there we go. I'm Leon, Leon Gersing. I'm a single dad, I read a lot of code, I work for GitHub with that guy SpicyCode in the back, and you can find me on the Twitters as Ruby Buddha. Yeah, if you need me, just shout.  So take whatever I'm saying with a complete grain of salt. Most of this is colloquial, but I want to start off with how we understand one another, where we get our ideas, and how those ideas influence one another. So when we think about a group of individuals, there's various different fringes and places where you can inter-bingle, and you might find yourself in some of them one day and in another another day, and that's totally fine. But we really, when I'm talking here in over-broad generalities, this one I'm talking about in culture, where we're saying we might have like a dominant culture that sets like the tone, the pace. These are the rules that we have made up, and these are the rules that we live by. And eventually that dominant culture is gonna be hit with a subculture. People say, well, dominant culture is not for me anymore. I'm gonna go over here and have a cigarette. And that won't be enough for some others, and they may find a counterculture, one that actually doesn't live in harmony with the dominant culture, like a subculture might. A counterculture might actually actively try and combat the dominant culture, because they don't wanna agree with their rules.  I think people from this area know a little bit about what I'm talking about there, right? Yeah. I was out there yesterday too, it was a lot of fun. And then there's the fringe. The fringe, like almost everybody except the fringe is like, I don't know what they're doing, but I'm happy they're doing it over there, right? And there are things to learn from all of these. And as information is accelerated, as we're allowed to hear the stories of our brothers and sisters from other lands, from other disparate groups, no matter how close, we know a little more about ourselves, maybe where these ideas came from and how to acclimate to them. But how do you know when there are boundaries in your way? How do you know that your culture has started to stagnate where you need to actually reach out to other communities, find new avenues, maybe modalities of thought? It's very difficult to do. Now, as I'm going through, I know I'm talking about culture and that could be very personal for people. It could be very emotionally triggering. But I like to think of what Frank Zava once said, after walking on stage at a wood stock and said to a bunch of hippies, if you don't know who the hippies are, they look a lot like me, they're very unclean. They make a lot of really good music. And he said, we all wear a uniform, which is just really upset them because part of their culture as a subculture was that they were in stark defiance of the uniform of the dominant culture. And suddenly someone came up from the counterculture and said, hey, hey guys, you're doing it too. Good luck, right? So I don't mean to say any of these things to offend or to hurt or marginalize or place anyone in any kind of group. That's not what I'm trying to do. What I'm trying to notice is where ideas come from and where do our rules come from and how flexible are those rules? So a good example of something like this is when I was coming into software, one of the methodologies for producing software was the waterfall method. And our group at the time, Lexus Nexus, used it very well, like it seemed to work. We would go from one stage to the next to the next and then move it all the way back when something didn't go right. There were like 20 different groups I had to learn about before I could ship anything. But for some reason, it seemed to work there and it was fine. And then suddenly the dominant culture starts asking questions like, wait a minute, this seems really ridiculous that I have to wait all the way again to do anything. So people start thinking about it and people start moving on.  Let's throw that to the ground and just go with four rules, right? And that's maybe where the agile manifesto comes into play. And then they say, okay, well, we don't need all of your write-offs and sign-offs and HIPAA and SOX and all these other things. We don't need that. We just need a philosophy, which is what the agile manifesto is. It's just a doctrine. It's a philosophy. It's one group's idea of what healthy process looks like. So wait a minute, that looks pretty cool. Those guys and gals over there seem to be shipping some code pretty quickly. I think maybe we should adopt some of that and take it on as our own, right? Yeah, and this is when people start to say, punk is dead. So we look over and we go, oh, they're angry. Oh, and they're really motivated and they're really getting things done. Why don't we just ape the motions of what they're doing without actually understanding what goes in and creating that culture?  And punk still exists. You can find great punk. It's out there. You can get punched in the face at a show and have a good time, right? It's there. And it's not at the Avril Lavigne show. You will be punching yourself probably in the face. Sorry, Avril Lavigne fans. I didn't mean anything by it. You did. But in order to actually know a culture, you have to identify that there is a difference, that there is a boundary, that there's something there that you might be able to draw from and bring back to your home. And that's fine to do so. You can go throughout. But you can't just cargo cult it. You can't just build a gun out of wood and say, why doesn't the magic work? It's not necessarily the path to wisdom. It's not the way to find yourself understanding what caused the subculture to be created in the first place. So we get this. My friend Charlie Baker once called Agile with a little lay anything where we are doing Agile by name and not in practice. So what we ended up with in certain situations was, oh, yeah, we have a scrum table. And yeah, there are cards on the wall. And we're now doing waterfall with cards on the wall. That's awesome. Didn't take the time to go into those communities, to go and sit with their brothers and sisters and understand them, talk to them, see what their pain was. And even if that pain could be replicated in the same system, maybe there was a different system that could have come out of it if they had tried, if we had gone down that path. Maybe there will be a new one where we do, right? Who knows? You've got to get out of your place, though. I always say, when thought is replaced by process, you end up with something like this. Yes, the escalator to stair land. It gives the illusion that what you have is real. It gives a myth. It gives you something to talk about. But it's a bit of your stomach you could feel that there's something wrong, that there's something off, missing, that it's hollow. Well, it doesn't move. I don't. And this piece is something that I've found in doing a lot of user group stuff. There's a feeling that I've got something important to say and all the power to say it. Only I don't know what it is, and I can't make any use of that power. To know that you have all the tools in front of you, but you don't know what to do with them. These are the pieces where we wander. These are the places where we can take this power. We can take our understanding of the journey that we've been setting on at this moment. And we can walk into cultures that we don't understand and start to learn. We can be open cubs. Jose was talking about what was that style of Ruby that was like inconsiderate Ruby. I thought that was hilarious. I hadn't even heard of that. I think you should be inconsiderate more often. Like why not? Who's to say it's not right or wrong? Take it in and let's try it on for a bit and see what happens. Let's use some of this power to be creative and destructive and amazing and rebuild whatever we want and not get trapped in the desert of the real. The Boryard has this concept of the Borgia map, where this great empire exists. And the king says, I would like a map, a tapestry that's as big as this screen. And it has every part of our culture on it. It has every mountain in our land. It has every waterfall that we have. It has every grain of sand on it. And it looks as glorious as the empire when it was created. And then over time, the map starts to deteriorate a little. But the kingdom behind it is gone. It has started. The mountain has turned to sand and rubble. The waterfall has stopped flowing. And what that map represents no longer even exists. And yet that's the thing they're going to worship. So if you find yourself stuck in a dominant culture that is rigid, that hasn't found a way to loosen its boundaries, realize that it may be time to move out and seek new ideas, to find new ways to bring these fresh ideas back into your life. Rather than worshiping an ideal that no longer exists. I love this quote. It's at the beginning of that very book. The simulacrum is never that which conceals the truth. It is the truth that conceals that there is none. And the simulacrum is true, which he quotes in the book to a classicist. But I've scoured a classicist. It's not there. So he was trolling me from page one. And I like to retranslate this, that we simulate reality and we know it. We lose touch with our actual reality. And the simulated reality becomes real. So be careful when you're fighting for things like idiom. And idiom is just an idea that came before you that a lot of people liked. It is not concrete. It can be broken. And it should be. Every day, as software developers, you are inventing reality.  Think about that. That is an immense amount of power and immense amount of freedom.   You don't necessarily have to invent it literally. I mean, invent it figuratively. Pull together the parts of other communities that make sense to you, that seem to be working the same way. Not just because they're heroes. Not just because they're famous. Not just because everybody knows them by name. There are plenty of new names that we have not yet heard of and I can't wait to hear them. So how do you change your perception? How do you enter yourself into fringe culture? How do you get over there? Well, I believe that perception is reality. Oh, yeah. So if the prescribed path, go to school. I go and I get all my education. I get a junior high degree and then I go to high school and I get my high school degree. Then once I got my high school degree, I go to college and I get my undergrad degree. And once I get my undergrad, then I'm gonna get my master's. Once I got my master's, get my PhD, maybe two or three.  And everybody lives happily ever after, right? No, wrong. There's no prescribed path. There's no easy one way to anything. And these are the smartest and most creative people in the world. So we don't need it. But what if I'm trapped? What if I can't get out? What if I feel like I've seen everything and I know everything? Well, rule one, there are no rules.  It's true.  That's right.  Humans, and they all make mistakes, and that's fine.   You're like, no, no, I don't like that at all. Peace. Done. No big deal. You might find yourself feeling like you're dejected or rejected from whatever group you happen to be in at that moment, but that's not necessarily a bad thing. It's okay to say things that might hurt or offend those around you. What's not okay is to repress it. What's not okay is to let it never be said. That's where we all lose. So there are other ways to do this.  I don't know. But I love Brother Bill Hicks. Here's an old comedian from the United States and he says, wouldn't you like to see a positive LSD story? Today, a young man on acid realized that we're all madder and just merely energy condensed to a slow vibration that we're all one consciousness, experiencing itself subjectively. So there's no such thing as death. Life is only a dream and we're the imaginations of ourselves. And here's Tom with the weather. All right, Brother Bill Hicks, you want a good LSD story? I'll give you one. Here's a guy right here who published a paper on the use of LSD 25 for computer programming. Bet you didn't see that in your textbook, did you? Well, I have it in the show notes. You're welcome to take it after this. It's, yes, that and the recipe for LSD. But this is a person who is looking around at all of the available techniques, all of the available processes, all of the things that his contemporaries could tell him about how to write software. And this is the 70s and he's looking and he says, I can't even wrap my head around it. He had to write this huge programming assembler and we couldn't see it. So had heard about some very interesting things happening with low dose LSD and went and tried that. And after a night of throwing away a lot of code, had some idea of the entire system could imagine it in a way they had never imagined it before. Now, I'm not saying to go out and do LSD for any lawyers who are in the room. I'm just saying that there are different ways to see the world if you could just take a minute to let go and check, what, is something helping? Is someone passing around LSD? I knew you were. So we live in a world where there is more and more information and less and less meaning. So we have a very interesting bit where we actually now have this time where we can see these cultures. They emerge, they come to us. We don't necessarily have to do what I did 30 years ago, like wandering through Europe or wandering through Asia, just trying to find people that I could relate to. We found each other. Look, we're here, right? So even though there might not be meaning in these texts in this information, meaning is derived. Wisdom is derived through experience. So if we're feeling this way, where we're inundated with information, where we feel isolated from the world, let's use this information to then ingratiate ourselves into these other worlds, to find out what's there, to gain the wisdom that brought them to that same place. And we may be able to repurpose it in ways we can't even imagine, but it may not be on the path that we expect it to be. For instance, as you heard earlier, I was doing some.net and iOS and all this. I mean, I was just basically looking for a community of people that were a little weird. And then somebody introduced me to Wise, pointing you guys to Ruby. And it blew my mind. Blew it open. I still want the onion. That was promised at the beginning of the book. It doesn't have to be. If you are dying to share Ruby, then find a way to do it. It doesn't necessarily have to be the same learned Ruby in 24 hours. You don't have to go down the path that has been before you, just because you think there's a pot of gold there. Anyone who's ever been down the prescribed path will even tell you, eh, it's a hit or miss. You may get paid. You may not get paid. So who cares? Is it for the money? Is it for the experience? Is it for the journey? For me, it's for the wisdom. Finding that wisdom will come in all kinds of crazy ways. Sorry, a little fun fact there. Anybody know George, we have Serrat here, right? Pointillism. All of this person's contemporaries were constantly telling them this is worthless. He worked on this painting for two years. Worked on this Chromaluminescence for two years. Now we call it LCD, right? Just pixels, right? Same thing. He was way ahead of his time. Way, way ahead. Yeah. And if he had listened to those contemporaries, if he had stayed because he was in that particular culture, we may never have gotten it. He may never know how impactful his work has been, but it was. Even to people not in his group. And your wisdom will come from masters that look completely different than you expect them to. For instance, if you want to know how to do a grand jeté, this might be the person you wanna ask. Just because I don't know how he does it. I can't do that. And I have basically his same bill. I gotta find this kid, right? So on your path, on your way to wisdom, to enlightenment, to the place where you become the person that you're trying to be. Remember that that person that you may discount or just credit because they sound weird or scary, that's the time to soften. That's the time to open your heart. That's the time to be embarrassed, to be a child, to be a fool, and let it all in. It doesn't have to change you. It will, but it doesn't have to. One of the most courageous things we could do is listen to someone and be heard by someone else. And let them have their voice. Let them have every bit of it. We don't have to assume any of it. We don't have to take on any of it. But we can be there for one another and we will grow from that. So part of this is just that people say to me, Leon, I would love to do what you're talking about. I simply don't have time. And I say, yeah, yeah, you're right. If you say you have no time, then you don't. Time is not something that we have created right now, time is, man, love to meet our time. That's what we did. We said, oh yeah, there are seconds, a millisecond, 15s and whatever, and be there at eight o'clock, not eight o'five. But that's a myth for thousands of years. We ruled ourselves by, oh, when noon happens, like when that big orange thing is up there, I'll get there when I get there. We're here, the Catalonians are probably like, yeah, we're on beach time. I'll take an extra five minutes. It's fine, it's wonderful. You have time for everything you want to have time for. You make that choice, and it is a choice. One of these things that really got me going was this quote by the Dalai Lama in which he understood that man sacrifices his health in order to make money, then he sacrifices money to recuperate his health, and then he's so anxious about the future that he doesn't enjoy the present. And the result is that he does not live in the present or the future. It lives as if he's never going to die, and then he dies having never really lived. And I hope the same is not true for Ruby, for all of our beautiful programs that we write. I hope they evolve and grow and find wisdom in other cultures, and they find a way to live now in the present, in that moment where we're confused. Oh, come on. This always reminds me of this lovely poem. I always wonder why birds stay in the same place when they can fly anywhere on earth, and then I ask myself the same question. And this is that moment when I'm sitting in front of my desk and everyone has told me that every idea that I've ever had is wrong, and I gladly get up and move over to another one, because I can. There's no reason why you'd have to stop your journey short. There's no reason why you can't get out there and be a part of it right now. There's no reason why if something doesn't make sense to you, you can't look it right in the face and say, I love you, but I don't understand you. Can you please explain it to me? Most times people will have no problem doing just that. This always reminds me of this one thing because the medium, of course, is affecting the message. So I must give you this little poem. It is tiny. If you will so indulge me. It is The Perfect Tie by Shel Selverstein. And it reminds me of everything I want to learn in life. It reminds me of the truth versus the lie. There was once a boy named Gimmy Samroy, and he was nothing like me or you, because laying back and getting high was all he cared to do. And as a kid, he sat in the cellar sniffing airplane glue, and then he smoked bananas, which was the thing to do. And he tried Coca-Cola, breed helium on the slide. His life was an endless search to find the perfect tie.   And speed just made him rap all day, and reds just laid him back, and cocaine rose with sweet to his nose, but the price nearly broke his back. He tried PCP and THC, but they didn't quite do the trick, and poppers blew his heart, and mushrooms made him sick. Acid made him see the light, but he couldn't remember it too long. And his sheesh was just a little too weak and smack, where it was just a little too strong. Gueludes made him stumble, booze made him cry until he heard of a cat named Babab Fats, who knew of the perfect tie. Now Babab Fats was a hermit cat he lived up in Nepal, high on a craggy mountaintop up a sheer and icy wall. But hell says Roy, I'm a healthy boy, I'll cry or crawl or fly. So I'll find out, and I'll find that guru and give me a clue as to what is the perfect tie.  Up a trail no man could conquer, to a cliff no man could climb. And for 14 years he tries that cliff and back down again he slides. He sits and he cries and he climbs again, pursuing the perfect tie. He's grinding his teeth, his coughing blood, he's aching and shaking and weak.  What's happening to Fats says Roy with joy, I've come to state my biz. I hear your hip to the perfect trip. Please tell me what it is. For you can see says Roy to he, I am about to die. So for my last ride Fats, how can I achieve the perfect high? Well, dog my cat says Babab Fats. Here's another burnt out soul who's looking for some alchemists to turn his trip to gold. But you won't find it no dealer stash, no, not on some druggy shelf. Son, if you would seek the perfect tie, you must find it in yourself. Why you jive motherfucker says Jimmy some Roy, I have climbed through rain and sleet. I have lost three fingers on my hands and four on my feet. I have braved the layer of the polar bear and taste the maggots kiss. Now you tell me the high is in myself?  And my ears before they froze off said Roy had heard all kinds of crap but I didn't climb for 14 years to listen to that sophomore rap and I didn't climb up here to hear that the high is on the match.  All right, okay, says bad bad bad.  There is a land beyond the sun that's known as Zabali, a wretched land of stone and sand where snakes and buzzards scream and in the devil's guarded blooms the mystic titsi tree and every 10 years it blooms one flower as white as the Key West sky and he who eats of the titsi flower will know the perfect tie and the rush comes in like a tidal wave and it hits like a blazing sun and the high at last the lifetime and the down don't never come and but the Zabali land is ruled by a giant who stands 12 cubics high with eyes of red in his hundred heads he waits for passers by and you must slay the red eyed giants and swim the river of slime where the mucus beast they wait to feast on those who journey by and if you survive the giant and the beast and swim the slimy sea there is a blood-drinking witch who sharpens her teeth as she guards that titsi tree to hell with your witches and giant says Roy to hell with beasts of the sea as long as the titsi flower blooms there is hope blooming in me and with tears of joy in his snow-blind eye Roy hands the guru of five then back down the icy mountain he crawls pursuing the perfect tie well that is that says Babapet sitting down on his stone facing another thousand years of talking to God alone it seems Lord says fat it's always the same old men or bright eyed youth it's always easier to sell them some shit than it is to give them the truth I'll leave you with a few last thoughts one from my favorite here Mr. Thompson morality is temporary wisdom is permanent that which someone is judging you for today may celebrating you for tomorrow you follow your heart you follow your crew you find your people and you move together you figure out where that wisdom is you know it's in that journey and as you're afraid and as you don't wanna share that code and as you're feeling little down just remember something I tell every student I've ever had that code is a living representation of who you are right now no more, no less that's it it is who you are and who you are going to be we don't know may show where you came from and that's good but it is a living representation of you right now and I hope that you will share it and I hope that you will join me on this so long thanks for all the fish I've really appreciated your time go out there and be somebody we've got a couple of minutes for Q&A if anyone has any questions I know it was sort of more motivational and technical but there's one question here in the middle there's just a mic coming to the side hey there what was the first time that code made you happy? the question there was what was the first time code made you happy? the first time is hard to remember I've done a lot of drugs but I remember the first time that it made me truly blissfully happy was when I could share it with someone else so I remember hacking on my own trying to figure out what it all meant and it wasn't until somebody who wasn't interested at all just came by and said what are you doing? I said wait a minute here come here let me share this with you so for me that was the joy and I think I've been chasing that high ever since as many people as I can get to thanks for that you want another question? no I can't get you illegal drugs awesome let's give him a big round of applause Liam


It may seem as though the narcissist hates you. It may seem as though they can't stand to be in the same room as you But then they won't let go.  If you go to a restaurant and you don't like the food or the service there You're probably not going to go back But narcissists will return to you again and again Even though they profess that they hate you Even though they claim that you're not good enough for them or you're abusing them When if they really believe that They probably wouldn't be around you No narcissist is going to tolerate that kind of treatment.  The truth is the narcissist cannot survive without you Which is why they will hold on to you for dear life But they want you to think that what you're doing is good enough They want to keep you looking at yourself Rather than seeing that they're not doing anything for you When you meet a narcissist you soon discover that they have nothing to bring to the table They might have potential It might look like they're working towards something But it never manifests into anything great It's just future faking They're just making you believe that if you hold on a little longer, you will eventually get something back in return But that never happens And even if they did manifest anything they would only keep it to themselves They're not going to share it with you Regardless of how much you have given to them Narcissists are in survival mode. All they can think about is their own survival They can't consider you when they constantly feel like they're hanging off the edge for cliff And no matter what you do for them, it will never make them feel like they're safe or secure It has nothing to do with you You cannot change how someone feels about themselves But no matter what you do for them, they will always want more And they will never think about giving anything back to you in return When you get involved with a narcissist, you will notice that they never have anything to bring to the table It's always the other person that is bringing something to them It's like the narcissist thinks they are the table. There's always something going on with them There's always something they want There's always something they need you to do It's like they can't do anything on their own Like they're big babies It's like they constantly need to be birthed or fed The main difference is that narcissists never grow or develop They always stay the same So you don't get to look forward to a future where they are finally able to do things for themselves Well, they aren't constantly depending on you They will always need you around It's like they're handicapped It's like they have a condition that restricts their ability to function physically mentally or socially And that is why they always need you around The narcissist may hate you But they won't let go because they need you They need your money They need you to take care of their domestic duties They need someone to use as their emotional punching bag And no matter how hurt you may be about how they're treating you It's not good to change their behavior When you reveal your vulnerabilities or human emotions It will only make them hate you even more Because they want the focus to be on them They're the victims here They're the ones who need assistance That's how they want you to see it And any time that you try to spend focusing on yourself Will only make them resent you When you try to show the narcissist that they're hurting you That's when you will see who they really are They will deny it or minimise it They will gaslight you and shift the blame onto you But they will never hold themselves accountable They will never make consistent changes to their behaviour Because they don't really care about how you feel Unless it has to affect how they feel about themselves All the narcissist really cares about is their own feelings and how they see themselves They don't even see you as a real person When they targeted you They saw you as an object Something that existed to meet their needs They saw everything that you had to offer But they had nothing to give to you And as the relationship progressed They began to milk more and more out of you They gradually raised their standards and expectations of you While giving you nothing in return But they have to minimise everything that you're doing They have to make you feel like you're not doing enough Because otherwise Rather than looking at yourself and thinking you're not good enough You would look at them and realise how they've done nothing for you You would realise how much you've lost and how little you've received in return And of course the narcissist doesn't want you to meditate on that They don't want you to realise that they haven't even done a fraction of what you've done for them Because once you accept that it'd be true It means you've got to hit the brakes It means you've got to stop everything you're doing for them And they don't want you to stop They want to get as much as they can get from you So they will trick you into thinking that you're not doing enough for them They will act like they don't appreciate everything you've done As though anyone else would do so much more When secretly They know that they are not deserving They know that there isn't an equal exchange They know that you deserve so much more than what they're giving to you But they will never tell you this Because then that would mean that you would have to stop everything you're doing for them It means that they would have to start pouring into your cup When they never had anything to give to you If the narcissist left you today You would probably be fine Your quality of life would probably improve But although the narcissist hates you They have no choice but to stay Because they're in survival mode And they know they can't survive on their own They know that they would struggle without you And that is why they will hold on to you for dear life Even though it may seem like they hate you Because they have no other choice They will milk as much out of you as they can Until they have enough to move on Or they will target a new source who has everything they need And then they are out of there Like you never existed Because all they care about is what you can do for them Or how you make them feel You're just an object to them They don't even see you as a real person But no matter how much you give to them or do for them It will always be minimized They will never be grateful They will always act like you could have done more Well they never brought anything to the table They never did anything for you Because your dealing with someone Was emotionally underdeveloped It's like dealing with a child And they see you as their parent They expect you to give everything to them The child isn't supposed to give anything back to the parent It doesn't work that way And the narcissist is like a child that wants to be the parent They want the most beneficial part of both roles They want the entitlement of the child Or having the authority and control of the parent But like many teenagers may behave towards their parents The narcissist can hold a grudge and be very resentful They always feel like you should have done more for them And while that is understandable for someone at that age It's a completely different story when you're dealing with an adult Someone who should be mature enough to take care of themselves Without constantly depending on someone else But this is what narcissism is all about A person who expects more from you Than they expect from themselves A person who wants everything from you Without giving you anything in return While making you feel like nothing you do is good enough But still sticking around Because secretly They've got a good thing going on with you They get whatever they want, whenever they want While putting in a minimal amount of time and effort But they will act like they're exhausted They will act like they can't do any more than what they've done When they haven't done a fraction of what you've done for them And you should already be able to see where this is going If they've only done a fraction of what you've done for them And they're still expecting and demanding more from you They're just going to milk as much out of you as they can And when they're done They're going to claim that you didn't do enough for them They're going to say they were doing everything for you When in reality Rather than being in a relationship It's like you were raising a child You invested all of your time, energy and money Things that you could have used to build yourself But instead it gets wasted on someone Who doesn't even appreciate it And in return you get nothing back Other than hate, anger, bitterness and resentment You become their caretaker Someone to look after their emotional or financial problems It's like you're giving everything you have to someone Just so they can use it to destroy you It's like you're paying for your own execution They always leave you worse off than before you met them They come into your life with nothing And leave with everything Thank you for watching I hope this video raised it with you Please like, comment, share and subscribe Click the bell icon to receive notifications For my future videos Check out the new NARX 50 website NARX 50 at the Code of UK Where you can read my blog posts, book coaching sessions And join our support forum If you liked it tonight My PayPal link is in the video description Coaching inquiries You can email me at coaching at NARX 50 at the Code of UK Thank you for watching and I'll talk to you soon


So today we will do a little bit of discussion of cavity dumping. Now this is more for the sake of being historically correct and more for the sake of completeness of knowledge because most of the time when we do ultrafast studies we use titanium sapphire lasers and unfortunately titanium sapphire lasers cannot be cavity dumped. Cavity dumping was a very very popular technique when die lasers were used. It is not a technique by which you produce ultra short lasers per se. What you do is you take the pulses out. There is some narrowing down of laser pulses also but more importantly you can take the pulses out of a particularly you can take it out of a die laser cavity and is attractive because as you will see cavity dumping is a technique in which the laser is always on. We are also going to discuss Q-switching after this. We have already discussed mode locking. Cavity dumping is like mode locking where the in the sense that the laser is always on. As you see in Q-switching the laser is not always on and we will talk very briefly about pulse picking which we use in our lab. As I have said earlier also it is a wasteful technique. We threw away most of the energy. We use only one-tenth of it or one-twentieth of it. In cavity dumping when we are not taking the pulse out actually the power of the laser goes up in that time interval. That is why it is such a good technique. It is unfortunate that we cannot use it with the femtosecond lasers we have now. So in cavity dumping once again we use an acoustic modulator. We have talked about mode locking. How you do mode locking using acoustic modulator? That time we said that you have to use it. You have to use the AUM, AOM in Raman Nath regime where L was much much less than lambda square by 2 pi small lambda. Where capital lambda is the wavelength of sound wave small lambda is the wavelength of light. In case of cavity dumping I think we have discussed it in the previous module as well. In case of cavity dumping we have to operate this AOM in the so called Bragg regime. And Bragg regime means L the thickness of the medium is much much greater than capital lambda square by 2 pi lambda. So essentially you end up using you have to use much higher frequency of acoustic wave. L has to be greater than capital lambda square divided by something. So capital lambda would better be small. If capital lambda is to be small the corresponding frequency has to be large. So we will see what kind of frequency is typically used in this technique. Secondly it helps if you have a longer interaction length. And here what happens is when you work in this regime all the higher order refractions are eliminated. Only the 0th order and 1st order rays are sustained. Omega plus or minus capital omega if you write in angular frequency. Sometimes it is written as omega 0 plus minus capital omega. So for now this is what we will consider. We will consider that here when light falls on the Bragg cell part of it goes straight undeflected and it does not interact with the medium. Part of it gets diffracted and it gets frequency modulated by capital omega. This is what we have discussed in the last meeting as well. Now what you do is, in fact we discussed this as well in the last meeting but we went too fast and I think nobody understood anything. So let us see if we understand it better if we make animations. So this is a part of the laser cavity that we are showing. As we had said earlier it is important to remember that there is no output coupler here. All mirrors are highly refracting and we are showing only one end of the cavity. So this is M1, this is M2 and the laser beam goes this way. Somewhere here we have the gain medium and somewhere here we have the other high reflector mirror. Have you understood the cavity? Have you understood what the cavity is? This is M1, this is M2. What is shown there? Then the laser comes from M2 this way. There is a light. This is where the active medium is and this is where the other reflector is. And there might be other mirrors in between. But the crux of the matter is that this is one mirror, the end mirror. M1 is the starting mirror. M2 is the other curved mirror that is important for our discussion. So this is the simplest cavity that you can think. M1, AOM, M2, then the gain medium, Dijet or whatever it is, say M3. This is the cavity. So it is a closed cavity or high reflectors. So you can think that if you pump this gain medium here there will be a laser. There will be a laser beam in the cavity but it will never come out. The question is how do we take it out? We take it out by cavity dumping and how does that help? So before showing you the beam path and all, one thing that I did not say earlier and it is important to say otherwise it is very difficult to follow what we are saying is that this bragg cell here is kept at the focus of M2 and at the center of M1. Focus of M2 that means any light hitting M2, a parallel beam of light hitting M2, if it is normal to the tangent at the point of hitting then it will get focused on to the bragg cell. And since the bragg cell is at the center of, if you draw a line from the center of the bragg cell to the surface of M1 that will be the radius of curvature of M1. What happens then? Let us see if you remember any geometrical optics. I have a curved mirror, spherical mirror. I draw a ray from the center. The ray goes and hits that curved mirror. Where does it go afterwards? That is for focus. Yes? No, no I am saying at the center. For a concave mirror usually focal length is half of the radius, is not it? I am saying it is not at f. It is at 2f. So this is one of the main reasons why we did not understand last day. Remember those ray diagrams that we used to draw? This is a curved mirror. Something like this comes it will get focused. A ray that comes through the focus will, yeah, now from 2f center the ray comes and hits the curved mirror. Where does it go? It retraces its path. Why? Because if this is the, this is a radius then the tangent here, right, the radius is perpendicular to the tangent, is not it? So it is like normal incidence. What happens for any mirror in case of normal incidence? The light retraces its path, is not it? So for a beam that originates at the center of the mirror, all the rays will retrace their paths. I did not say it in as many words in the last day, whereas that is why it was a little confusing and also I showed everything together. Today we are going to show it step by step. Have you understood now what is going to happen with light falls? So then let me draw this. This here is the interactivity beam.  Now for M2 the Bragg cell is at the focus. So this is what the path of the right will be, all right? Now what I have shown is, I have shown the part that goes straight. The part that has the part of the beam that has not interacted with the radio frequency. Will this be the only thing or will there be something else? You follow me, right? What I am saying? E0, interactivity beam, E0 is the, you can say electric field associated with it. That falls on M2, gets focused on the, and I am talking about only one ray. So it goes through the Bragg cell. One part of it goes straight. Is there another part of it that does not go straight? And you can refer to the diagram above. We are working within Bragg regime. So won't we get another beam that will get diffracted like this? What did we say? That you will get the 0th order and the first order beam. Second, third, what we used in modulocking Ramanranth regime, we had omega 0, omega 0 plus minus, capital omega plus minus 2 capital omega plus minus 3 capital omega so on and so forth. Here there is no n omega, only omega, capital omega, omega plus or minus capital omega depending on the angle of incidence, okay. Here we have written, well we will see what we have written. Are we okay? So let me call this, let us say that the electric field associated with this beam that with the first order beam is E1. And let us say the electric field associated with the beam that went through straight is E2, okay. Now let us consider E1 first. After hitting M1, where will E1 go? It will retrace its path, right, because the Bragg cell is at exactly the center of M1. So it will retrace its path, okay. And again it is going through the Bragg cell. So part of it will go straight, we will call that E1 dash. Part of it again we will get bent. And when it gets bent, it will be made by the exactly the same angle. So now it will take the path that you would get if you produce this E2 line back to M2, is that correct? Yeah. So we will call this E1 double dash. Have you understood so far? Now in the direction of E1 double dash is that the only beam that is there or is there something else? What we have said so far is E0 falls on the Bragg cell after reflection in M2, gets divided into two parts, E2 and E1. Then E1 gets reflected by M1, comes back to the Bragg cell. The part that goes straight, we call it E1 dash. The part that bends, we call it E1 double dash. Now think in the, so what will be the fate of this ray that I have drawn associated with E1 double dash? After hitting M2, where will it go? It will go back along the direction of the intra-cavity beam, is it not? So it will be sent back to the cavity. But will only E1 double dash be sent to the cavity or is there something else that we have not considered yet? Exactly. E2 also hits M1 and retraces its path, goes back to the Bragg cell. Then what happens? A part of it goes straight and by the convention that we have used so far, we call it E2 double dash. A part of it bends, but before that, well I forgot the sequence of animation, sorry. So now the field that is sent back to the cavity is E1 double dash plus E2 double dash, understood? So that is what I was talking about. A part of it goes back to the cavity. Now to complete the other part, what will the other part be? E2 after hitting M1 has come back to the Bragg cell. The part that has gone straight, we have called it E2 double dash. The part that bends, we can call it E2 dash. So in this direction, we have a total field of E1 dash plus E2 dash. And now see what has happened. When the beam came from the dijet and hit M2, there was only one spot. But since Bragg cell has performed a diffraction, the beams that come back create an additional spot which is associated with the field E1 dash plus E2 dash. Where will that go? That does not go back into the cavity, does it? Let us see it goes in this direction. So in whichever direction it goes, you keep a prism and the prism acts as a retroreflector. You do not even have to keep a prism. You can keep two mirrors or you can keep this retroreflector that we use whatever it is. Conventional prisms were used in die lasers and this is the beam that comes out. So see even though this laser has no output coupler, by using cavity damper, you can take a part of the beam out. Part of the beam that goes out is of the field associated with it is E1 dash plus E2 dash. But interestingly for every such cycle, E1 double dash plus E2 double dash goes back to the cavity. So this is what I was saying. Even while you take the light out, the laser beam inside the cavity grows. That is why you get a good power out of the laser. Have you understood now? So even if you stop here, I think qualitatively we are good. We have understood how it works. But we will not stop here. We will give you a little bit of a feeling of what kind of numbers we can think of and why it is that during cavity dumping, the repetition rate gets modulated. Why does it that it gets cut down? In the cavity dumped synchronously modulok die laser that I used as a PhD student, repetition rate would typically be cut down by a factor of 10. It would go down to one-tenth of what the repetition rate was initially. And that was important because we did TCSPC with it. So you could not work with 78 MHz kind of repetition rate which is intrinsic of the modulok output of the pump laser. Now again I will ask the question that you did not answer.  Now I hope you understand what it means. Now let us try to see what kind of expressions we get. We want to know what is the expression of E1 dash plus E2 dash. So to start with we will write E0 as A0 e to the power i omega t. Now I want to ask you something. You want to say something about E0 or A0? What does it look like? It looks like it is a constant. Is it really a constant? Do not forget what kind of laser we are talking about. We are talking about a synchronously pumped modulok laser. Cavity ramping is only take the thing out. Even if I do not do cavity ramping, it is modulok nevertheless. So E0 is actually a pulse. E0 is an electric field associated with a pulse. So it actually has a little more complicated structure. E0 is not just a constant. That also is something more. We know already the expression of pulses that you get out of modulok systems. So that is the real expression. Here we are writing this only because otherwise expressions become too large. And you will see the implication of it once we are done with this discussion. All right. Output field is E1 dash plus E2 dash. So question is what is E1 dash, what is E2 dash? Let us see if we can figure that out. To start with that, let us first consider that this might look a little scary because we are chemists after all. We are not very good mathematicians perhaps. But this much of, we will not even try to solve it. We will tell you how it begins and then we will tell you where it ends. Now in the Bragg cell also there is this periodic field that you have because you have applied a sound wave. Let us say it is ESS for sound equal to AS e to the power i capital omega t plus phi s. What is capital omega? What is omega in this kind of expression? When I write for light E0 equal to A0 e to the power i omega t, what is that omega? Angular frequency of light. When I write it for sound, ES equal to AS e to the power i capital omega t plus phi s. Capital omega is the angular frequency of sound, that is all. And what is phi s? It is a phase of sound wave. So you might remember those of you have worked with the Pulse speaker particularly you play around with the phase, do not you? So that it is that phase. There are discussions in which they have not considered phase. I am going to share some paper with you. They have actually simpler expressions but phase is a very real thing. We even have a knob to control it. So that is why we will keep it for now. So after the first pass E0 light with associated electric field E0 passes through the Bragg cell the first time. Then what happens? It gets split into E1 and E2. So E1 turns out to be E0 multiplied by square root of eta multiplied by e to the power i omega minus capital omega t. This could have been omega plus capital omega t also multiplied by e to the power i pi by 2 minus phi s multiplied by e to the power i phi 1. Of course you can write this expression in several different ways is not it? Because it is a product of some three exponential functions. So you can add up everything. You can group them differently. This is how it is done in the book. So we will go by this. Let us see what every factor means. E0 we have talked about already. What is eta? Eta is the ratio of intensity of the diffracted beam divided by intensity of the input beam. So this is ratio of intensities. This here we are talking about field E1. What is the relationship between electric field and intensity? What is the ratio? Which one is the square of which one? Intensity is square of electric field. So therefore it is not difficult to understand that electric field is square root of intensity. That is where this square root comes from. So square root of eta no problem I hope. What is the next factor? e to the power i omega minus capital omega into t. Where does this come from? Because you have a light wave with angular frequency small omega. You have sound wave with angular frequency capital omega. They are interacting. E1 is a diffracted beam. Do not forget. So in diffracted beam you are going to have interaction between the two. That is where that omega minus capital omega comes from. Next one is something that will take axiomatically. Where does this pi by 2 come from all of a sudden? Does anybody know? There is no pi so far out of the blue. Where have I got it from? Well this comes because the interaction is between light wave and sound wave. What kind of wave is light? Electricity is fine. I am only talking about the electron electric part. Transverse wave. And what kind of wave is sound wave? Longitudinal. So whenever there is an interaction between longitudinal and transverse wave that pi by 2 term comes in. So these are all very well known from physical optics and all. And then this phi s we have kept and then last one e to the power i phi 1 that you have to consider. Again for a simplistic picture you can set it to be 0. Experimentally you can play around and make all the phi is 0. If there is no phase difference between anything. Perhaps you can try and do that. But this is the general expression. The point is this. Your light is travelling through some glass quartz. So some phase difference will come in. That is why that e to the power i phi 1 comes. Then what about e 2? Now knowing the expression of e 1 let us try to guess what the expression of e 2 will be. E 0 will be there. Then will we have root eta or will we have something else? Remember e 2 is the electric field associated with the light that has gone through straight. No interaction with sound. No. The capital omega comes later. Right now I am only talking about the root over eta. You are right. Well your answer is the correct answer to the next question that I was going to ask. It is right that e to the power i omega t that is what we will get. We will not get capital omega there. But can we come back to the correct answer of the question I have asked? What about root eta? Will it be root eta or will it be something else? No diffraction. But see eta has to be there in some form or the other because after all e 0 is getting split. It is getting split into the diffracted beam. The beam is getting split into the diffracted beam and not diffracting. Intensity of diffracted beam is idiff as we have written. What is the intensity of the beam that has gone through straight? i n minus idiff. So what is 1 minus eta? 1 minus eta is i in minus idiff divided by i in. So here instead of eta we are going to have square root of 1 minus eta. And then we have e to the power i omega t minus phi 2. The phase difference will come. But this is what we have considered so far. This is a Bragg cell. e 0 has hit m 2, gone to the Bragg cell. One part has gone straight. One part has been diffracted. We have not got to e 1 dashed yet. We have to consider e 1 dashed. To do that what we have to consider is there is another pass in the other direction. So e 1 and e 2 both hit m 1 and come back. So this is e 1, hits the mirror, comes back, goes to the Bragg cell again. e 2 hits m 1, comes back, goes to the Bragg cell again. And now for the sake of gravity we are not going to try to work out what is the expression of the field for light that goes back. Let us see if we can get say e 1 dashed. What is the light that goes out? e 1 dashed, is not it? Yeah. So after the second passage what will e 1 dashed be? I say e 1 dashed is which one? The beam that goes straight or gets diffracted. No, e 1 originated from diffraction that is okay. But that was the first passage towards m 1. While going towards m 2, e 1 dashed is the part of e 1 that goes straight. So now see whatever was the original expression for e 1 that will be there. But then something like eta over square root of eta or some square root of 1 minus eta has to come. What will come here? Square root of eta or square root of 1 minus eta? It is going straight. It is not being diffracted this time. Square root of 1 minus eta will come here okay. This is what will happen and you can have some additional, you can have some additional phase difference that comes in okay. That is how you get this carry expression okay. So people who work in optics or physics students and all for them it is very easy. They do not have to do it so slowly. Look at it they understand everything. But then we might not. So it is better to go a little slower. Similarly, you can work out yourself. e 2 dash gets a very, now we have something we like. We have symmetry. We have 2 expressions e 1 dashed and e 2 dashed which look more or less the same. So that is why see earlier it was multiplied by square root of 1 minus eta already. So now it is multiplied by square root of eta okay. The next part of the math is not difficult just manipulation. You do it and this is the final result I am going to show you. Well we get an expression for e 1 dash plus e 2 double dash sorry e 1 dash plus e 2 dash. But then finally what we care about is intensity right. Mod square of that intensity is going to be intensity of the output beam is that right. Intensity of the output beam this is the expression we get for that intensity of the output beam okay. We stop here and we continue from here in the next module.