Now let's talk about resistance. And I want to start by clarifying some terminology. So we've got three really close terms. Resistance, resistor, and resistivity. Our resistance is the ratio of voltage to current. A resistor is a device that creates resistance. And the resistivity is a material dependent property of the device. Now resistance was defined by Ohm's law. So that's how we know that it's the ratio of voltage to current. To work further on, we're going to temporarily go back and review what we've already learned about current density. Both of these equations, J, was my current density. In one case, it was the current per area. In the other case, it was the conductivity times the electric field. Since both of these things are equal to the current density, I can set them equal to each other. Well, why am I doing this? Well, this is part of how I define my resistance equation for a wire. See, if I start with this equation, then I can remember that the electric field is equal to a voltage over a length. If I substitute that in, I'm going to get a slightly different equation. Now for this equation, I want to just rearrange it. I want to move my current over to my right-hand side. And I want to move my sigma and my L over to the left-hand side. So if I cross-multiply, I'm going to end up with this. I got one more little shift to make because 1 over sigma is going to be a new quantity called rho. Putting that in here, I now have this equation. And this side of the equation over here, well, it's equal to the voltage over the current, which means this must be equal to my resistance. So let's take a better look at this equation. Capital R is resistance. The L was my length of wire, and the A was my cross-sectional area of that wire. And this rho is our resistivity. So the resistivity was a material-dependent property. The L and the A tell me something about the geometry of a particular wire. So I know something about the material and the geometry. Let's look at the resistivity in a bit more detail. So again, resistivity has this symbol here, which is the Greek letter rho. But remember, its name is resistivity. And don't confuse this usage of rho for resistivity with our previous usage of rho for charge density. We have to reuse the symbols in physics sometimes. So we brought this rho resistivity in because it was 1 over the conductivity, 1 over sigma. So that means the resistivity is the inverse of conductivity. For units, that means it's going to have units of ohm meters. You may remember that conductivity had units of 1 over ohm meters. So now we can look at our overall units for our resistance equation. Rho, we just said, has units of omega times meters, ohm meters. For my geometry, I've got length over area. So that's going to be meters per meter squared. Now, my meter squared on the bottom is going to cancel the 2 meters up on top, leaving me with units of ohms for my resistance. So resistance is measured in ohms. Resistivity is measured in ohm meters. So that's resistance, particularly the equation for resistance for a wire.


Hello and welcome to this session. Today I will help you with polynomials. Let us discuss the following question. Find the quadratic polynomial each with a given number, the sum and the product of the zeroes respectively that is 1 by 4 comma minus 1. Let us understand the key idea first. A quadratic polynomial when the sum and product of the zeroes are given is given by fx is equal to x square minus sum of zeroes into x plus product of zeroes. Now let us write the solution. Given to us is that sum of zeroes is equal to 1 by 4 and product of zeroes is equal to minus 1. Therefore by key idea now let us find the quadratic polynomial. We get f of x is equal to k into x square as it is minus sum of the zeroes which is 1 by 4. Therefore 1 by 4 into x plus product of the zero which is minus 1. Now solving the equation we get k into 4x square minus x minus 4 whole divided by 4. Now this 4 gets cancelled by this constant. If we take this k as 4 to satisfy our given condition the sum of zeroes and the product of zeroes. Therefore we get our required polynomial as x is equal to 4x square minus x minus 4. Hope you understood the problem. Bye and have a nice day.


What's up everybody? It's ya boy Spencer X and today we're doing five things every beatboxer needs. Let's go. All right, item number one. Water. As a beatboxer you need to stay hydrated. I can't tell you how many times I've been to the studio or I've been to a performance or I've been just beatboxing to my own practicing and I forgot to bring a water bottle. You don't need a big jug like this. I'm using a two liter bottle from Enviro and I just find this super helpful because I filled up once the entire way through and that's my water for the day. I don't need to overthink it. Do I have enough water? Do I have to buy any? No. Boom. You got it all here. This is the only thing you need. You could have a water bottle put it in a cup you know but any way you spin it hydration is key. Water is your best friend. Beatboxing is a physical activity just like any sport or singing or dancing anything that requires you to do movement. That also requires hydration. Obviously there's thousands of health benefits for water but the point is to stay hydrated.  It'll save you from a lot of things. Do it. Drink water. So that's it for number one. Let's get to number two. A metronome. I use a Yamaha metronome. I don't think they make these anymore. I've had this one for quite a while. You can buy a metronome pretty much at any music store or go online to amazon.com. A beatbox's job is to keep time. I'm gonna say it again. A beatbox's job is to keep time.  Bam! You could put it on your phone. I use an app called Pro Metronome. I don't know if you could see it. Pro Metronome and it does the exact same thing. You can change the BPMs here. This pretty much does the exact same thing. Worst case scenario you don't want to buy one of these. You don't want an app for one of these and you're trying to find a way to keep time. You're trying to find a metronome for you. You can just go to google.com and just type in metronome and it does it for you. So super sweet, super simple. If you're watching me through a computer or you're watching me through a phone there is a way. Keeping tempo and keeping time is so important. No matter if you're collaborating with an artist, if you're doing a song on your own, if you're beatboxing to a track or if you're performing with a band, it's just great for practice. So that was number two. Let's go on to number three. You didn't see that one coming, did you? Yeah, I'm using Ecolips because big live. Look, you don't want to be a person that's in this situation like Spenser, I got bars, bit of beat. I got you. One second. Don't do it. Simply said, you want to keep hydrated. You want to keep moisturized because this is your instrument. Just like a violinist would take care of a violin or a flute player would take care of a flute.  The healthier you are, the better you will perform. I didn't used to have water around me all the time. I didn't used to have chapstick around me all the time. These are things that I've learned that just that helped me along the way. Chapstick, water, boom. So that was number three. We're going to go on to number four. It is an audio recorder. Now, I'm using the H6N from Zoom. It's pretty sweet. It's pretty nifty. I use it because I can connect microphones to it. There's four inputs there. Also record into it. A great audio recorder will give you great audio quality, but you don't necessarily need that. You're fine getting by with your phone. And so boom. Another thing on the list. Most phones have a voice memo app. You know, see right there? Boom. And you can easily record yourself at any time, any place. I like to think of audio recording as a journal.  Let's say there's one beat you really, really want to use for your next video or one beat you really, really want to perform. Because as soon as you think of a beat, it's actually pretty hot. A super helpful way of logging your beats so you can keep them for later or you can work on them later. You know, we're human. We forget things sometimes. So that was number four. Now we're going to go on to the last one. Number five. This is the AKG D7. I use this bad boy because it has a dual shock mount, which means there's pretty much no handling noise. If you see here, the windscreen actually fits on your hand just like that. Cups perfectly for beatboxing. Now AKG is notorious for having great beatbox microphones. You don't want to drop $100 or $120 on a microphone. There's a much better option. This is actually my first microphone and I can swear by it. It's the Behringer XM 8500. It has a built-in pop filter. It has an internal shock mount. It really gives the AKG a run for its money. You're looking for a dynamic microphone. You want to have a low handling noise. You want it to be feedback resistant and you want it to be tough. But what's so important about having your own microphone just in general is being able to practice with it.   So that wraps up my beatbox hacks, beatbox tips, beatbox list. It wraps up my beatbox thing. I just wanted to share some things that really brought a lot of value into my life. And hopefully they help out you guys, you know, whether or not you're an aspiring beatboxer or you're already doing it at a professional level, I think that the little things matter. The most beautiful thing about beatboxing is that it's free. You know, you were given this instrument at birth and you hone it and craft it into whatever you want to craft it into. I'm not saying like, you know, you can't be a beatboxer without these things. Honestly speaking, you don't need any of these things. You probably need water. But do I think that these things have helped me get to another level of beatboxing? For sure, if you're looking to move into a more professional level, these things are not necessarily needed, but they're very, very helpful. If you liked any of the products that you saw here today, check out the links in the description, you'll find the items right there. If you liked this video, give it a thumbs up, leave a comment down below. And if you know of an aspiring beatboxer that really wants to push their game to the next level, share this video with them. I hope that this helps you as much as it has helped me. Thanks for tuning in. I just wanted to share a couple things that make my life as a beatboxer a lot easier to mix out. Hope you guys have a great day.


Well, folks, we have some rumors for you today coming from the same source about two different things that apparently apply to Nintendo Switch 2. One of them directly does, because it involves the dev kits for the Nintendo Switch 2, you need an update that, well, it's kind of a minor thing for us gamers, but a really big thing for developers, and likely just going to make a lot of games look and perform a lot better. And it's weird talking about it since the system hasn't been announced, but hey, it's still pretty interesting, and I'm really glad that this update's out there now. Again, still a rumor, also included in this is something to do with GameCube and NSO, and this rumor is a bit speculative, but it's based on something Nintendo has actually updated, which to me is quite fascinating, and again was pointed out by the same source, although we can argue Nintendo is actually the direct source of this, getting us really excited for GameCube on Nintendo Switch 2. That being said, folks, I want to thank you so much for being here. We're on our road to 150,000 subscribers. If you're enjoying this content, you want to see if there are all the latest rumors and news from Nintendo. We have a brand new news show launching next week. It's going to include a little bit more than Nintendo, but still mostly focused on Nintendo. We still have our individual topics as well. It's going to be a lot of fun. We're building a whole new set for it, whole new computer. It's going to be great. Just subscribe to the channel, everyone. It would be greatly appreciated. All right, let's go ahead and dive in, because first up here, we have good old Nash Weedle. All right, for those who don't know who Nash Weedle is, he's gotten a few things correct over the last couple of years, and look, all his other stuff is still pending. So we kind of consider Nash Weedle to be a possibly really reliable person, but we just got to wait for things to pan out. Now, Nash Weedle put out there that the Switch 2 development kit receives an important update. It's based on translation from Spanish by Google. So it says, now the tools allow us to go one step further. So this is something that his supposed development sources have told him. And he said, I can confirm that this is direct information from a developer. It's not speculation. Of course, for all of us, it's speculation because we have to rely on Nash Weedle's trustworthiness. Anyways, he has an opinion that he thinks it's an update in reference to re-scaling, which it really is all talking about upscaling. When we think about the Nintendo Switch 2, one of the biggest things that is rumored for it is DLSS. And it's been rumored to be the 3.5 version just without frame generation. And that's entirely possible because the feature set there is not frame generation, but the other stuff in 3.5 is usable on older Ampere architecture. So this is one of those things where we kind of think we know that it's using the T239, which is an Nvidia chip set and is based on Ampere. And Ampere can use certain features from 3.5, although it typically doesn't in the PC sense. It is technologically capable. We've heard this is custom, yada, yada, yada. And we can get into a lot of the technical details, but the bottom line is that it appears at least according to Nash Weedle. And again, still a rumor that, yes, there was an update to the dev kits that now enable them to rescale or upscale their games even better. And that's just nice. It's just another step in the process. It also goes to show that clearly the system isn't ready to launch today, because if it was, developers would already have the full suite of tools they need to take advantage of DLSS or maybe even a custom, you know, upscaler that Nintendo is providing. And they apparently haven't because they've been given this update recently, which allows them to, well, now do a better job with upscaling and rescaling their games probably for multiple resolutions. Remember, you got the handheld resolution, you also got TV resolution, and TV resolutions can go from 8K to 4K to 1080p, even still some 720p TVs out there. So just things for Nintendo to consider with a upscaler or any sort of rescaling technology. This is just good news. All it means is games are going to look better and possibly even perform better. But we don't know what better means because we don't have the system out or announced and we haven't seen games for it yet, or at least haven't seen games officially. So take that for what you will. It's just something to throw out there. Now we get to this next one that deals with GameCube. And this is where I am starting to get a little excited here because Nintendo is directly involved in this. Also spotted by Nash Weedle. So Nash Weedle put out to that Nintendo seems to have a GameCube emulation ready. So GameCube emulator. It recently updated a patent based on this system. And why would they still be updating patents based on GameCube stuff if they're not planning to do anything with it? Which joins other recent patents on Cube console control. So you know it's obviously here, GameCube, Nintendo Switch Online, obviously this is just a fan made logo. But we get over to here and it says in a game system, according to a further embodiment, the game information storage medium contains at least two emulator programs, each of which correspondingly emulates two types of second game machines having different architectures from each other and from the architecture of the first game machine. The game selection program selects any of the emulator programs according to the game program of the game title selected by the player. In a game system, according to another embodiment, the game information storage medium includes at least two emulator programs that emulate the second game machine and at least two types as the first game machines, each having architectures different from each other. The game selection program starts the execution of the game program of the game title selected by the player based on the emulation program, according to the architecture of any of the first game machines. And look, that's a lot of mumbo jumbo that essentially means that there's just a lot of stuff going on behind the scenes to make multiple emulators run, and this emulation update is in regards to one that refers to GameCube games, which I just find really, really interesting. It's not something that I am, you know, worried about. It's possible that they're talking about combining multiple emulators together in a single package. And that might be a big update for Nintendo Switch 2, because the way that the emulation process works for Nintendo Switch Online right now is you have to download a Nintendo Entertainment System app, a Super Nintendo Entertainment System app, a Game Boy app, etc, etc. It's not all combined together because they just separate them out as individual emulation programs. But what this kind of sounds like maybe this update with the GameCube related one is a combination of emulators into a single application where the game selection selects which emulator to use. And this could just be a friendly user update for Nintendo Switch Online emulation for Switch 2. Now, it could obviously, this whole combining them together, could be an update for Nintendo Switch as well, but since this update appeared in a GameCube emulation patent, that to me just sounds like Nintendo's really talking about the next system here, combining things together, and yes, the fact that this is in a GameCube patent just makes you feel like, well if they're still updating this patent, maybe it's because they are planning to bring GameCube emulation to Nintendo Switch 2 and thus bring it to Nintendo Switch Online. Probably in the premium tier, and the reason we say Nintendo Switch 2 exclusive isn't because Switch can't run GameCube emulation, we assume it can, it's significantly more powerful than a GameCube, but it would just be to help push people to the next platform, and look, Nintendo could still add GameCube to the current Switch, we can't dismiss that possibility, it just seems like at this point if they're going to add a new big system like that, that that's like a selling point for a new system, Nintendo likes making selling points, maybe it'll be on both, so that's possible as well, and then you know what they say when that happens, everybody wins. So I don't know guys, this is just the latest on the rumor mill and the speculation you guys let me know what you think about this stuff down in the comments below. I am Nathaniel Ruffaljantz from Nintendo Prime, and I'll catch you guys in the next video.


Welcome all to the last day of the workshop, so this is the schedule for today I will spend some time talking about the instead of future trends I will cover some interesting trends in computer networks these will include both things that are already existing as well as things people are working on the very informal talk I will get into it soon at the conclusion of this talk I will also summarize some takeaways from the workshop our expectations from you going forward after this after the tea break we will have a workshop feedback as well as the valedictory function where you can provide your thoughts on what you felt about the workshop whether we could do something to improve it so on so forth. And then we will break for lunch post lunch we are expecting you to fill an online feedback provided on Moodle, so you are supposed to log in through your Moodle accounts and fill up to the survey as I have mentioned earlier also such kind of surveys are very important they give lot of feedback for us to improve the workshops in the future, so sincere request you all to please fill the survey even if you are not able to do it today afternoon the survey link is open for the next few days even after you go back you can fill the survey. So, with that let me get to the talk, so this talk is on interesting trends in computer networks a word of caution is that my area of research is in the wireless space, so I know lot of stuff that happens in that space in the wired space I am not actually as conversant with the kind lot of research that happens, but that said I do know some of the stuff that is hot in these areas. So, what I am going to provide is just a high level overview of some interesting things that happen in computer networks, the idea is to just provide a very high level picture in order to get into any of these concepts you need much more time in fact we could run a course itself based on this topic, since I am going to provide a very high level picture I mean the take away or the end result of all this is you will just pick up a few buzzwords as to what is happening and have some vague idea of what I am what I am talking about. In order for you to know anything more in depth you actually have to pick up the topic, pick up the resources do Google or pick up some text books and read it in depth yourself I am not going to provide any such thing. So, they will when I explain stuff I am sure there will be more questions than answers in your head that is the intention, the intention is not to explain everything in a lot of detail the intention is just to expose you to some of the interesting things that happen in computer networks. The idea is for you to take this forward on your own and get to know it in detail. So, just expect to know some buzzwords at the end of the talk with some vague understanding of what is happening. So, with that said so again I will go according to the protocol stack here and then wind up with some high level overview. So, at the physical layer most of the effort these days is to increase the speed. So, when we are talking about wired networks we are already in the GVPS range. So, it is pushing forward to 10 GVPS and all is already there. So, we are trying to really push up the speeds. So, the lot of innovation that happens at the physical layer is in increasing the speed of the link. More work often happens in the wireless space where when we have Wi-Fi networks for example, when they started out they started out with just 2 Mbps and then slowly it got hiked up to 11 Mbps then through 54 Mbps then 108 Mbps. So, as you can see over the years the rates have been constantly increasing and now we are talking about GVPS in Wi-Fi. Similarly, in the cellular space also when we first started it was just 10 Kbps, but slowly the speeds have started to increase and now when we talk about 4th generation which is still not a deployed there is still work going on in that space. We are talking about again 100 Mbps throughput to be offered in a mobile environment. So, in order to achieve any of these high data rates there is lot of innovation that happens at the physical layer. Let me just mention one technology which is extensively used in wireless though it finds used even in the wired space which is called OFDM, Orthogonal Frequency Division Multiplexing. So, OFDM is a very hot area. So, this is what 4G employs, this is what future Wi-Fi will employ, this is what future Wi-Max will employ more or less any wireless technology is converging towards OFDM because it is an extremely spectrally efficient system. So, I will briefly mention what this is that said OFDM also finds used in the wired space in this digital video and audio broadcasting. So, let us see what OFDM is, there are a few things you need to know before you understand OFDM. In fact, whatever I am providing is again extremely high level overview OFDM is very complicated I can do an entire course based on OFDM. So, I will just tell a few things as a background and then you will understand OFDM better. So, there is this concept of spectrum which I have already covered as part of the course any signals for example, if you take a big sequence like this, this has some spectrum. So, we represent it like this. So, the spectrum is infinity it spills over, but typically we cut off at some point and say this is the spectrum of the signal. Another thing which is important to understand in this context is what is called carrier modulation. So, if you see any system be it Wi-Fi, be it cellular, be it Ymax, be it even regular Ethernet you have this bit stream that is in the represented here and this bit stream has the spectrum. What we call this is baseband because any system is going to have signals in this form baseband means it will range from 0 hertz to some f hertz. Now, when you say carrier modulation what you basically are doing is the entire spectrum be it wired or wireless also ranges from 0 hertz all the way till giga tera hertz and so on so forth and you could use the space to communicate. Now, when you have different systems especially in the wireless you want to allocate different chunks of the spectrum to different systems. For example, you might decide to allocate the chunk around 900 megahertz to cellular similarly you may want to I am writing it further, you may want to allocate let us say something near 2.4 gigahertz to Wi-Fi. So, this is how you split up this particular spectrum to the different services when something happens like this. So, baseband as I said will always range from 0 hertz to f hertz. Now, you need to move this baseband to wherever the spectrum has been allocated to you. So, for that what you do is you do what is called carrier modulation. So, you take whatever signal you have in baseband. So, this is the baseband signal and you multiply it with a carrier frequency which is 2 pi f c t. So, f c is the carrier. So, this will correspond to 900 megahertz in the cellular spectrum it will come correspond to 2.4 gigahertz in the Wi-Fi so on so forth. So, this is carrier modulation. So, these two things you need to know that there is spectrum and then there is this carrier modulation that is happening. Now, let us get back to OFDM. So, what OFDM does is the fact that there is FDM shows that this is a form of frequency division multiplexing. So, what you have is let us say you have this entire spectrum at your disposal in frequency division multiplexing what you do is you are going to assign different users this spectrum like this. So, user 1 has got this chunk, user 2 has got this chunk and user 3 may have some other chunk so on so forth. So, entire spectrum you are dividing it up into chunks like this. This is by the way not OFDM this is frequency division multiplexing. Now, the problem with frequency division multiplexing is that you have to provide these guard bands between two different users because as I showed the spectrum spills over into other frequencies also you try to reduce it to the extent possible, but you still need to provide a guard band such that the usage of user 1 spectrum does not spill into user 2. So, this is typically what happens ok. So, I will have to read all. So, this is FDM you have different users in this particular fashion so, this is FDM. What OFDM does is it does as I said it is very spectrally efficient. So, what it does is it divides the spectrum into these very narrow band carriers. So, this entire spectrum is divided in this particular fashion and as you can see there is no guard band not only that the chunks that are assigned are overlapping. The reason why it is able to do like this is because of this orthogonal feature. In other words these carriers are chosen these are all the carriers. So, as you can see earlier we have talked about single carrier here you have multiple carriers. So, OFDM falls under this multiple carrier modulation technique. So, you have multiple carriers right. So, just to contrast in FDM you would have given this carrier to this user and this user is going to use this carrier and spread his data around this particular carrier. Whereas, here in OFDM there are multiple things that happen. So, as I said this thing goes on you will select some of these carriers for user 1, some of these other carriers for user 2 and some more carriers for user 3 and so on so forth. So, you have divided the spectrum into multiple narrow band channels and each of this a bunch of them you are assigning to given user. So, it is very spectrally efficient because it avoids this guard band through the use of this orthogonal carriers and not only that it for a given user itself here you are just allocating one chunk it is a single carrier modulation based on FC whereas, here you are allocating multiple carriers in OFDM. The reason why you do this has to do something with mitigating multipart. As you go for higher and higher data rates multipart becomes an extremely difficult thing to handle and OFDM handles it very beautifully through the use of this single carriers. Now, you may have questions about what this multipart is how does it handle all that is for you to read up on your own, but this is more or less what OFDM is in a nutshell. So, to summarize the physical layer at computer scientist we do not pay that much attention, but that said lot of work that goes on at the physical layer is in improving the data rate and as I have showed an example of it which is OFDM whose main objective is to get the maximum data rate for a given spectrum allocation. So, it is extremely spectrally efficient and it is the technology of choice in many of these wireless technologies. So, most wireless technologies are converging towards OFDM they often throw in MIMO this also is a buzzword multiple in multiple out antennas. So, this has got to do with using multiple antennas again to improve the data rates. So, with that we will move on to the next layer which is the link layer. Again compared to the wired networks there is lot of activity that happens in the wireless networks because the challenges at the link layer basically the media access control becomes challenging because in a wireless network everyone can hear everyone's transmissions. So, media access control has a very important role to play since we are not dealing with wireless networks let me just focus on the wired networks. In wired networks there is Ethernet itself since it is extremely popular as well as very low cost there are lot of efforts in using Ethernet in different settings there is something called Metro Ethernet whose main objective is to extend Ethernet in a metropolitan area network. So, Ethernet is often viewed as a local area network. So, it just covers a small region whereas, metropolitan area it covers a region of an entire city. So, that is a much larger network. So, how can we leverage on the low cost of Ethernet and cover a metropolitan area network. So, there is lot of innovation here at the physical layer I mean this is against not something very new it has been there for quite some time. So, that is something people are looking into. There is similarly something called carrier Ethernet again this is using Ethernet in the telecommunication space where originally the telecommunication space has been mostly proprietary they have ADM switches they have their own signaling so on so forth. But to leverage the low cost of Ethernet as well as the migration towards IP they are also trying to move towards using Ethernet as part of their backbone and that is where a carrier Ethernet comes into play. So, apart from this is like the different technologies that are there as I said link layer there is very minimal even here because CSMA is no more applicable even in switched Ethernet. So, this is more like a physical layer stuff with some minimal link layer specifications which carry on from the regular Ethernet. But more importantly something that happens very interesting at the link layer is what is called VLANs these stands for virtual LANs. So, virtualization of a link in the form of a LAN is something which is extremely useful. So, there is a standard corresponding to this called A22.1Q in fact this also has been around since 1998. So, it is not something so new but something which we do not introduced as part of the course because it is slightly an advanced concept. But let me again tell a little bit of what this VLAN is. Suppose you have this building which is hosting let us say there are multiple floors between the building. So, this is floor 1, this is floor 2 so on so forth and let us say within each floor there are two groups let me call group 1 and group 2. Similarly within floor 2 also there is group 1, group 2 and similarly in floor 1 also and let us say there are two such buildings. So, the task of the network administrator is such that to interconnect these so the group 1 has lot of host, group 2 also has lot of host and you want to interconnect these host such that they can interact with each other. But at the same time you may also have some concerns that you do not want group 1 traffic to reach to group 2. In other words the broadcast traffic because of some privacy concerns. So, let us say group 1 is doing lot of research or it is accounting or the patenting kind of issues you do not want it to reach the kind of message exchanges that they do you do not want it to reach another group. That is not the only reason you may want also that group 1 for example, makes extensive use of the bandwidth whereas, group 2 made less use of the bandwidth. If you merge both of them group 2 is going to suffer because of group 1's activities. So, you want to provide some kind of traffic isolation for this reason as well. So, there are many reasons why you want to separate out the groups. In other words you want the group 1 to belong to one local area network and you want to group 2 to belong to another local area network. But the issue here is the way things are how do you put up interconnect them. So, for example, if you look at floor 3 if you want to connect these groups you naturally have to put one switch for group 1, one switch for group 2 maybe similarly one switch for group 1, one switch for group 2 so on so forth and thereby you have to invest in lot of switches which will increase the cost. But since they are on the same floor if I say I will use the same switch for all of them then it becomes an extended land where transmissions from one group you cannot prevent them from reaching the other group they will because the way it is the switching is done they are bound to go to the other group. The same concept I mean in order to interconnect these groups across two buildings either you have to invest in more switches to provide the isolation or if you want to use less switches currently the way switch tethernet is you cannot quite do it. So, they came up with this very interesting concept called VLAN where what they basically do is I will explain it in the context of just two switches. Let us say there is one switch that is being used in this building 1 and there is another switch S2 being used in building 2 and they are going to interconnect these two switches and you are going to impose this virtual LANs, virtual LANs is this LAN 1 will correspond to group 1, LAN 2 will correspond to group 2 on to this switched architecture. So, let us say there are all these users of group 1. So, this is all group 1 users I am representing it by a circle and there are also these group 2 users which I am representing by a square. So, they are all connected to the switch similarly at the other switch also. So, you have lot of the users that you are doing. Now, what you do in VLAN is basically configure the switches such that they are going to do very intelligent transfer of data. So, one way of viewing is each port of the switch you associate with a color. So, this group 2 is let us say associated with the blue color and group 1 is associated with say the green color. So, that is a typical terminology used in VLAN. So, what you do is whenever you get a packet from a port that is listed as green what the switch 1 does is it will send that packet only on other ports that are listed as green and it will since this one is interconnecting both of them this link will be listed as green as well as blue sorry green as well as blue. So, this will definitely send it out on this. Now switch 2 when it receives this packet say switch 1 will tag this particular packet saying that this packet corresponds to green and send it out and again switch 2 will only send this packet out on those ports that are labeled green. So, this is how VLAN is configured. So, VLAN involves switch configuration. So, there is a network administrator who sits down configures each and every port of a switch based on what the color of that particular group is and thereby the switch is going to do this kind of intelligent routing. So, this is there is in fact lot of stuff I have given a very high level overview you could color based on ports you could color the things based on MAC addresses you could color even based on IP addresses. So, there is lot it is a bit more complicated than what I have mentioned, but at a high level this is how you are imposing a virtualized LAN on a LAN which for all practical purposes is an extended LAN whatever you send ideally can go everywhere, but you are imposing restrictions on where you can send the particular frames. So, thereby realizing a virtualized LAN on a physical LAN. So, this is with respect to the link layer. So, let us move on to the network layer. So, at the network layer also lot of the research even to this day it goes into improving the router speeds. As I said as more and more traffic comes your routers have to handle lot of traffic not only that the link speeds are also progressively increasing. So, your router has to be extremely fast. So, there is lot of research that goes on how to increase the speed of the routers, how to quickly check your routing table to figure out where to forward a particular packet. Apart from this there is also lot of work that goes on providing quality of service for real time applications in the internet. So, there are these architectures called DIPSERV inter servers proposed, but it kind of got overtaken by DIPSERV. So, DIPSERV is what is typically used is called differentiated services. So, there are certain mechanisms that are employed as part of the internet to ensure that real time traffic is given more priority over other traffic. As I had mentioned earlier internet has been designed with best effort service in mind. So, here you are trying to do something more than best effort. So, thereby you need to change certain things about the way internet operates. So, there is research in this phase of how to provide quality of service in the internet. So, apart from this let me tell get into a little bit more detail in something called MPLS. MPLS stands for Multi Protocol Label Switching. This thing actually some people view it as layer 2, some people view it as layer 3 it in fact works in between layer 2 and layer 3. So, let me tell what this is again this is a buzzword which you may have already heard it is again very popular buzzword. So, what MPLS tries to do is impose virtual circuits in the internet in an IP network. If you recollect this IP network is based on datagram forwarding which is very different from virtual circuits. In datagram forwarding what you do is you have a packet this packet has a destination IP address. So, you look at this particular destination IP address and based on this you decide which among my interfaces should I forward this packet on. So, there is no concept of a circuit as part of the internet and datagram forwarding. So, what you are trying to do through the use of MPLS is impose a virtual circuit within this kind of IP network. So, the way that is done is just like in virtual circuits you attach a tag. So, you have this packet which has the ethernet header and then you have an MPLS tag and then you have an IP header. So, you inserted this MPLS tag between ethernet and IP and this tag is very similar to a virtual circuit tag. In other words this is a label which will use for forwarding. So, originally the interest in MPLS was in improving the speed of routers. So, if you remember routers do longest prefix match. In other words in order if there are multiple prefixes within a router and a given IP address could match any of them that search in the forwarding table takes lot of time. Whereas, when you have virtual circuits where you have a label in order for you to search for that label it is an exact match. So, longest prefix match will multiple entries can match it. So, you have to go through the forwarding table carefully whereas, in virtual circuit you have what is called MPLS originally intended to do was to use this exact match through the use of labels. So, you attach a label so that at the router which is an MPLS router instead of looking at the IP destination field you are going to look at this MPLS tag which will match in a way one can view this MPLS tag as if this is your forwarding table you have lot of entries. So, this MPLS tag will tell you where exactly that entry is within your routing table. So, given this it is going to now make the task of routing very easy. So, you just look at the tag you figure out within your forwarding table the particular entry and send it out. Now, how are these tags what label should be given how are the labels distributed that is again a lot of detail there I am not going to get into those details except to mention that even though the original goal was increasing the speed of the routers right now MPLS is extensively used for traffic engineering. What do I mean by this in this datagram forwarding when you have a packet with a destination IP address all packets that have the same destination IP address more or less will take the same path. So, for example, if you have a router here and you have packets coming corresponding to a given destination IP address you forward it on the same interface more or less unless the routing protocol has changed the path. But as long as the path remains the same everything is going to change the take the same path whereas what you can do through the use of MPLS is you could give different labels to the different flows and thereby ensure that they are taking different paths. So, MPLS as such is now used extensively to do some kind of traffic engineering in the internet. So, I know again I am sure lot of questions, but this is just an introduction. So, MPLS you can view it at a high level to summarize tries to make use of virtual circuit switching in the internet through use of these labels and its main goal while originally was to increase the router lookup speed, but currently its main goal is to do traffic engineering. In other words ensure that you have more control over which paths your traffic will take because the internet service providers will love such a feature. You do not want for example, one prefix to follow the same path you may want to load share load balance that particular traffic along multiple paths and this is feasible through MPLS by the use of labels. So, that is with respect to the network layer. Now, coming to transport layer. So, in terms of again research there are the usual TCP based research. So, there is lot of even though TCP is so old even to this day people are always tinkering with TCP to make it more efficient. Nowadays we have a wide variety of devices, smartphones, laptops, huge big servers that are connected with extremely high speed links and you also have a variety of applications that make use of TCP starting from HTTP to even real time applications to file transfer emails so on. So, TCP is one single protocol for it to handle so many diverse devices as well as diverse applications in some cases it will do well in some cases it may not do well. So, how do you find tune TCP such that it does well in many of these settings. So, there is lot of research that is always going on with respect to TCP. Similarly, so let me talk about a few other protocols in this particular space these do not quite fall at the transport layer, but they are in between the application layer and the transport layer. So, one is this RTP protocol which stands for real time transport protocol and there is a companion protocol called RTCP that stands for real time control protocol. So, these are used for handling multimedia applications this uses UDP as the underlying transport that is why I said they happen between. So, this is the applications layer this is the transport layer. So, this RTP RTCP are somewhere in between that is they sit in between. So, what is the reason for RTP RTCP. So, there are lot of applications that make use of multimedia and within multimedia also there are lot of for example, if you are looking at video there is MP4, H.26, blah blah. So, there are lot of standards audio also has lot of compression techniques. So, whenever you are using these video as well as audio streams there is lot of information you need to convey to the other end like what is the compression scheme that you are using, what is the format type that you are using and also these media players need some time stamping information. So, that they can synchronize the playback time. Now, for all this each originally what happened was each application since there is no support had to do this on its own, but then many applications that handle multimedia were coming up with their own proprietary formats to handle this requirement of specifying what the compression techniques are, specifying what the time stamp are, specifying what the sequence numbers are. Then they felt that we should probably have one common standard. So, that different applications can interplay and coexist. So, that is when they came up with this RTP. So, RTP's role is basically to define a particular frame structure to convey this information that is needed for multimedia applications like as I mentioned the sequence numbers or what type of compression techniques that you are using. So, RTP defines that particular format. So, whatever application comes it specifies this RTP will create the required kind of packets based on the specifications and it will use UDP and send it out. Now, what is the role of RTCP? RTCP is a companion control protocol where often the receivers have to convey some information to the sender so that the sender can adapt to the receiver behavior. So, what do I mean by this? So, sometimes some receivers have fluctuating bandwidth, sometimes they may have good bandwidth, sometimes they may have poor bandwidth. Now, as the receiver's bandwidth varies you want the sender to change the compression. In other words in some cases you want it to send a low resolution video, sometimes you wanted to send a high resolution video for which the receivers have to convey some feedback to the sender and that feedback is handled by this companion RTCP. So, basically it carries some error statistic reports from the receiver back to the sender such that the sender can change the behavior, the audio stream or the video stream. So, that is the role of RTCP. So, going back let me also mention another protocol in this space. This is also in between application and the transport player called real-time streaming transport protocol. This is again a protocol that is intended for multimedia applications and this is used for this play pause type of. So, in other words sometimes the media you have to convey information that play the video, pause the video, fast forward the video, rewind the video. All this information is handled by this particular RSTP protocol. So, these are some of the protocols that evolved because a lot of applications were having to do this themselves and there were many such applications in just like how TCP handles many applications, lot of multimedia applications they was felt a need that you need some standard protocols. So, they have been defined to lie between the application and the transport layer. So, that is with respect to the transport layer. So, coming to the application layer, again application layer I mean there is not anything majorly networking concept about it it is a more function of defining clever applications. Sometime back which is sometime in the 2000s there was lot of focus on peer to peer applications before that most of the applications were client server based. Peer to peer applications is where people like you and me we have all these machines they are going to interact with each other and come up with a way of sharing information. Some examples of peer to peer will be Napster which is none of these are in existence anymore, Kaza something which probably you are very aware of which is still working currently is this BitTorrent. So, BitTorrent is a peer to peer application that is used for sharing files. BitTorrent is a very clever design in fact to get into it will involve lot of detail. So, again I am not going to talk about it. So, at a very high level one can view these type of peer to peer applications as making use of individual resources be it bandwidth or CPU cycles to achieve a community task. So, for example, I have some files I wish to share and you have some files that I want let us both put together a resources and get this particular information. So, many of these things had gone out of business because of lot of legal issues because all these were being used to share copyrighted information which is illegal. So, many of these things have gone out of business because of that, but BitTorrent is something which is which is does not just do that. In fact, it some of the illegal BitTorrent sides do that, but mostly BitTorrent is used even by this media houses to distribute content. For example, if there is a gaming new game application that has come up they do use BitTorrent to legally distribute their things to a bunch of clients because it makes very you do not have to provision lot of big servers your intern making use of the clients resources itself to distribute the content. So, it is a clever idea again I cannot give you to limitation of time I would not get into it, but something for you to look into definitely. So, some of the things that happen in this space is social networking. So, this is again with the advent of Facebook, Twitter, WhatsApp so on there is lot of social networking. So, there is lot of research that goes on how to push content, how to pull content, how to advertise in the space so on so forth. So, basically what kind of push pull architecture should you use you collect lot of logs information do some data mining to figure out what is the general behavior of the users you leverage that to behavior and do a design architecture that makes this kind of dissemination of information very efficient. So, that is more or less with the application space. So, there are two other things that I would like to mention these are more from the research angle. So, within the space of computer network off late which is the past two three years there is lot of focus on two areas of research. One is called data center networking you may have already heard of lot of this cloud. So, basically clouds are supported through this data center networking. So, there are lot of this cloud applications you may have heard of Dropbox. Basically this is a storage solution that is provided in the cloud there is Amazon's i3 or something sorry Apple's i3 there are lot of this cloud applications that are available you can also use a cloud to get virtual servers. So, for example, running something like Bodhi tree I would have preferred if it were running on a cloud because the kind of resources it needs it is better served through a cloud especially when it has to scale to thousands of users. Similarly you could also use cloud to do lot of computational intensive tasks. So, for example, you collected lot of data and you want to mine the data to be figure out some patterns again you may not have the enough resources to do it. So, again you make use of the cloud for this data crunching kind of solutions. You may also want to use the cloud for a data basis. In other words if you are managing huge data basis of users so on again you need a very efficient system that is going to maintain this data basis and again cloud provides these kind of services. So, Google, Facebook many of them have these cloud solutions Amazon so on so forth. So, what is this data center networking what happens within this cloud? So, let me get into a little bit more detail. So, this is what happens within a cloud. A typical cloud which is the data center can have anywhere from thousands of hosts to lakhs of hosts. So, these are the number of machines that are there as part of the cloud. So, for example, if cloud or this data center has 1 lakh hosts that is part of the data center the operational costs are mind boggling. I think this takes about 72 crores per month to operate I mean it is not operational cost this includes the infrastructure costs also in other words 45 percent cost of this goes in this 1 lakh host. So, how did time come into play because these hosts have a limited lifetime 3 years 4 years. So, you amortize the cost over those many years and then determine how much it costs per month. So, basically if you are thinking of running a data center with 1 lakh host you should be prepared to spend 72 crores per month. So, that is the kind of and they consume huge amount of electricity so on and so forth. So, let us look a little bit about how these data centers look. So, there are all these machines. So, these machines are put in the form of racks you have all these racks arranged in this particular fashion and at the top of the rack you have something called top of rack switch it is called Tor switch this is basically a switch and these are all the racks these are hosts basically they also go by the name of blades. So, there are many such racks as part of the data centers. So, there will be many such racks as part of data centers and these top of the rack switches are in turn connected to what are called tier 2 switches and these. So, you have such racks in this fashion they are connected to this tier 2 switches. These tier 2 switches in turn are connected to tier 1 switches and these tier 1 switches in turn are connected to routers and these routers they may be such multiple routers and this router is the border router which has the internet access which connects it to the internet. There may be multiple such border routers, but anyway.  So, this is how a data center is organized. In other words so, the external requests come from outside through the internet to this border router then it is going to route this router in turn will pass to tier 1 switches, tier 1 switches in turn can pass to tier 2 switches and finally, through the top of rack switch the task can come to some host within this rack. Now, when you have some architecture like this there are lot of research issues. In fact, this one can view it as a network by itself. The internet also at the original days itself did not have these many hosts it had hardly a few hosts and there were lot of research challenges. So, here you are trying it is a huge network that you have involving lakh or thousands of hosts. So, there are lot of research challenges to handle within this one could be energy efficiency. How do you ensure that the energy consumption is minimized? One research issue is topology itself. How do you interconnect these hosts? I have shown you a hierarchical kind of topology, but this kind of hierarchical topology lot of these will become bottlenecks. So, for example, let me get into a little bit more detail. Suppose these hosts are connected by 1 g p p s links whereas, these are connected by 10 g p p s links, but there is lot of internal traffic going across the racks. For example, all these racks are talking all this hosts are talking with these other hosts and let us say there are 20 of them here talking with this. Since this 20 are sharing this you are only getting 0.5 g p p s per host whereas, internally they are able to communicate with a much better speed. So, how do you interconnect these switches such that you are not creating bottlenecks within the network? A related concept here is also you need to provide lot of fault tolerance. You people are paying huge amount of money to run their services in the cloud and if you say sorry the some machine failed and thereby could not run your service people are not going to be happy. So, you need to provide lot of fault tolerance. Fall tolerance will involve providing redundant links. So, even if one link failed there is always some other path to go from one place to other providing redundant switches. In other words if some switch failed there is always some other path through some other switch. So, there is lot of work that happens in how to interconnect these hosts. Some other area of research is load balancing. So, you get lot of requests and as I said a data center like this could serve multiple applications, it could serve email applications, it could serve storage applications, it could serve database applications so on so forth. So, you need to whenever you get these requests you have to distribute it across these different hosts. Some hosts may be idle, but their bandwidth requirements may be different, some hosts are very active. So, you need to kind of figure out where to send the traffic where by keeping into consideration the networking constraints. So, there is lot of research that happens on how to load balance the incoming traffic such that the utilization of the resources of the host is maximized. So, that is another area. So, there is also lot of work in the routing space, because as I said this itself is a big network involving lot of switches and routers. So, how do you route load balancing is a little bit at a higher level you are talking about load balancing in the application layer. Routers is how do you determine the paths when you have so much redundancy in the network while making better utilization of the network resources. So, there is lot of activity that happens in this data center networking space that is in fact, a very recent activity. So, if you want to pick some research topic there is a hot area, there is lot of papers that are coming up in the space. So, check this topic out. Another thing which is again which is a very what is it called an idea that is path breaking is something called software defined networks. There is lot of research when we will see them in action there is we do not really know, but there is currently lot of research in the space called software defined networks. What do I mean by this? This again has to do a little bit like virtualization. So, if you know of virtualization, the way virtualization is viewed is you have lot of these resources which are basically you use hardware. So, for example, you have your PC which is a hardware. Now, when you virtualize it you can run your windows operating system on it you could run your Ubuntu operating system on it or you could run any other operating system on it everything works in the virtualized space right. They are using the same hardware, but the software is going to be different. Before virtualization came into play the things were not like this the hardware came kind of custom built for a particular software. So, if you look at networks also the way things are currently is you have lot of these routers which is where there is no distinction between lot of the software functionality is implemented in hardware for efficiency speed purposes and often the configuration of these routers or switches is becoming a nightmare these days because you have to for example, the VLAN I did not get into the details, but configuration of a VLAN is a very difficult task. Routers also with the advent of quality of service support the kind of traffic engineering that MPLS throws in things are becoming extremely difficult to manage these particular networks and lot of the hardware has an inherent relation with the software. So, if anything you have to change it is not an easy task. So, the concept of software defined networks is where you are having this network of hardware and which we call the data plane and then you have a control plane where all the software involving the configuration runs. So, that way by appropriately changing your software you can quickly change the configuration of your routers or configuration of your switches. So, everything happens via software that is a paradigm shift in fact a big paradigm shift from how things are currently. So, there is a lot of activity that is happening on how to create such software defined networks. So, if you look at a router, router these days just does routing functionality, but if you view it as a hardware you could make it act as a router you could even make it act as a switch you can make it act as a firewall or you could make it act as a load balancer. So, it does not matter what you want to. So, at any given time you could make it act in different fashion. So, that is the idea of software defined networks. So, there is lot of work this is again one very hot topic in the area of computer networks lot of focus. Let me conclude more or less this is what I wanted to convey. Let me conclude the talk by specifying a few things if you are of a research oriented mind not only this typically if you want to keep up to date with the kind of research that happens in the space so that you could incorporate some of it as part of your teaching.  So, in the networking space there is this conference called SICOM. This is a top tier conference in fact getting into this conference getting a paper published in conference is extremely difficult. It hardly has some 10 percent acceptance rate and many people do not even bother submitting. In fact, it is 10 percent among the top people. So, it is very difficult, but it has some very interesting ideas that come up as part of it. So, SICOM is a conference the papers may be difficult for you to read, but as you keep on reading the background material they may be accessible. NSDI is another conference in the space that again deals with systems. Connext is also another good conference in the space. So, there may be a typically a tendency to read papers that are what I would call tier 3 or tier 2 papers these are conferences in tier 1 which means these are the top conferences. It is important to read papers from some top tier conferences just so that you know the quality of research that happens out there the amount of effort people put as part of research. So, this is typically in the computer networks which is the wide space they do have some wireless papers, but if you are more interested in wireless papers there are a bunch of other conferences which are again top tier in the wireless space. By the way SICOM also carries some wireless papers, but its focus is not quite wireless. So, this is MOBICOM, MOBI-SIS, SENSIS, MOBI-Hawk. So, these are some of the good conferences in the wireless space. Apart from this there is let me tell you two other workshops this is called hot nets. Again this falls in this category and hot mobile that falls in this category. The distinction these are conferences these are workshops the distinction is these two workshops have lot of futuristic work. In other words they do not the conferences typically publish work that has been implemented evaluated and so on whereas these workshops talk about ideas and initial implementations or initial evaluation. So, they do not really get into lot of detail, but they come up with bold ideas. So, if you want to check out what are some of the bold ideas that are out there then you should check out these two workshops which is hot nets and hot mobile. So, these are some things for you to check out with that I am going to end the talk on future or current interesting trends in computer networks.


RCA Victor, world leader in radio, first in recorded music, first in television, proudly presents... Screen Directors Playhouse, star Ray Milland, production It Happens Every Spring, director Lloyd Bacon The Hollywood Screen Directors present a tale for April evenings. The motion picture baseball story, It Happens Every Spring, starring Ray Milland in his original role of Vernon K. Simpson. In the spring of the hallowed year of 39, certain financial interests met in a smoke-filled New York hotel room. Present were the czars and barons of the Great American Popcorn Trust, the insidious hot dog monopoly, and the infamous soda pop cartel. Business was off. Sales were dropping. More popcorn, hot dogs and soda pop had to be sold. That, ladies and gentlemen, is how baseball was invented. And ever since then, it's happened every spring. Baseball. Let Monk Lannigan tell you about baseball. It don't make no sense. For instance, take the year of St. Louis Winner Series. It's the face of the season and I'm supposed to be a catcher. Only with the St. Louis there ain't nothing to catch. Our pitchers is either getting hit halfway to Kansas City or else tossing them so wild I need a ladder to snag them. So, one morning I'm out in the park talking it over with Jimmy Dolan, the manager, when this guy shows up. Hey, Mr. Dolan. He's a real serious-looking yokel with horn-rimmed glasses and he looks as much like a pitcher as Margaret O'Brien. But he walks up to Dolan and says, Mr. Dolan, I am a pitcher. And Dolan smiles the sweet Dolan smile and says, Scram. Mr. Dolan, you need a pitcher. I can win the pen and for you. Monk. Kindly make this crackpot disappear. Okay, son. We're busy. But I am not a crackpot. Dolan, he says he ain't a crackpot. He ain't a pitcher either. Dolan, it's a simple mathematical fact. I can win at least 30 games for you. My boy. What's your name? Simpson. No, no, no. I mean your first name. Vernon. Vernon K. Simpson. Well, Vernon... Beat it! Ah, Dolan, why don't you give him a chance? Maybe he's got something. I have indeed 30 games. If you can pitch one game, I'm the Queen of Sheba. Well, that was the year Dolan started being called Queenie.  Baseball. It don't make sense. My name is Deborah Greenlee. Debbie. And I think I know Mr. Mark Lannigan-Fields. I mean, it's all so crazy. You see, I was engaged to Vernon K. Simpson that year. The year that St. Louis won the series. We all knew that Vernon was a fanatic about baseball, and especially about the St. Louis team, but we never dreamed that... Well, after all, he was a very steady young chemistry instructor at the university, and father would never have given him his permission if he'd known that...  Father is president of the university. And one morning, about 7.30, Vernon rushed into the dining room while we were eating breakfast and said... Good morning, Debbie, darling. Dr. Greenleaf, I know this is a very odd hour to call. Oh, Vernon, what are you so excited about? Look at him, father. Yes, it reminds me, is there any more mush? Debbie, darling, I have to talk to your father. Dr. Greenleaf, I have to go away. Well, before you go, please pass the mush.  Money? Aren't you satisfied to starve to death like any decent young university instructor? Dr. Greenleaf, it's in connection with my university work that I'm going. That is, if you'll give me leave of absence. Oh, father, I'll bet Vernon has invented something. Yes, yes, I have, Debbie. Well, what is it? It's just the greatest... Well, it's a secret. Vernon, I've watched you closely ever since you came to the university. Every spring, Vernon, you've acted a little, uh, odd if you don't mind my saying so. Oh, I don't mind, sir. That's fine. Because this year, brother, you're crazy. Dr. Greenleaf, I'm sure I can justify myself if only you'd give me a chance. I implore you. Well, if it's for science. Oh, thank you, sir. You'll never regret it. And Debbie, darling. Oh, Vernon. I love you. I love you, too. And I'm going to be so long, son. Goodbye, dearest. Goodbye, my darling. Goodbye. Hold somebody, please. Pass the mush. And so Vernon walked out the door. And I'm not sure of anything that happened after that because... because, well, all I know is that was the year St. Louis won the series. If everyone seems to be confused, it's only natural. Because I'm Vernon K. Simpson, and, of course, I'm the only one who knows what really happened the year St. Louis won the series. We'll take up the story on the afternoon preceding my visit to the Greenleaf household. I was in my laboratory performing a very important experiment. As was my custom, I turned on the radio and was listening to the baseball report. It's not too early in the season to pick a pen and winner, but it doesn't take an expert to pick the St. Louis squad as the loser. The major weakness is the pitching department. Manager Jimmy Dolan would give his I.T. for one first-class early. I recall a distinct twinge of anxiety for the St. Louis baseball team, and I admit my thoughts were on the diamond as I bent over a white precipitate forming in a flask. Then... Baseball crashed through the window of my laboratory. I looked up just in time to see a group of children disappearing around a corner, and so I turned once again to my experiment. A shambles, a complete shambles. The ball had smashed through test tubes, beakers, flasks and retorts, and the remains of my experiment lay in the sink, a complex mixture of Lord knows what. I pushed aside these shards of glass and picked up the baseball, which was immersed in the chemical-filled sink. Looking at it, I lost my temper and threw it at the wooden floor, and immediately found myself grasping the baseball again. A surprising fact, for although I'd thrown the ball with all my might, it had not touched the floor. I wished to add that I pride myself on my pitching ability. The faculty developed since childhood in all moments when I was not studying. So, winding up, I let fly once again at the floor. After performing several similar experiments, I came to the scientific conclusion that the unknown fluid in the sink had imbued the baseball with an amazing property. The baseball was repelled by wood. I wish I could adequately describe my feelings at that time. I poured the fluid from my sink into a bottle, a bottle that could create the greatest pitcher in baseball history. Of course, when the fluid ran out, well, I didn't dare think of that. I thought only this. If I should cut a small hole in my pitcher's mitt, if I should pour some of the fluid onto a sponge, and if I should hold that sponge so the fluid would seep through the hole and cover the surface of a baseball, no batter on earth could hit that ball because it would, of its own accord, dodge the bat. So, being possessed of an opportunity to play baseball, make a great deal of money and marry Deborah Greenleaf, I asked for and received my leave of absence and traveled 78 miles to St. Louis, where manager Jimmy Dolan agreed to give me a practice tryout. He was doubtful, and so I am afraid was the kindly gentleman who was catching for me and Mr. Monk Lannigan. The batter stepped up to the plate and Monk called to me. Okay, young fellow, let's see what you got. Hey, who is this guy, Monk? Dolan told me to bat one over the fence. He wants to be a pitcher. Break his heart easy and get it over with him. Watch me. Come on, Beynon, steam one over. Very well. Sure it comes. Yikes! What kind of ball was that? Must have been an optical delusion. It ducked right under the bat. Hey, Beynon, let's have that one again. Certainly, Mr. Lannigan. I said, I've got to get glasses. Yeah, you'd better get some for me while you're at it. I saw the same thing. Hey, Beynon, come here. Monk. Monk was that guy, kiddin'? Jimmy, sure as I'm standing here, I saw it, he throws the screwiest ball I ever seen.  No. I ain't drunk. No. But you saw that ball do what it did. Yeah. Then you're drunk. He isn't, Mr. Dolan. I can throw a ball like that every time. Young fella?  I don't know. But anyhow, you got a job. And so it was that I, Vernon K. Simpson, by virtue of chemistry, became King Simpson, pitching giant of the St. Louis. And so it was that I turned my back upon the halls of learning simply because I discovered the secret of making a baseball goal. You are listening to the screen director's playhouse production of It Happens Every Spring, starring Ray Milland and presented by RCA Victor. In just four more days, the first baseball of the major league season gets tossed out and the fight to a series finishes on. What thrills for the fans of the game? And what thrills right in their own home for television owners who can't make the game? RCA Victor Eyewitness Television is the next best thing to being there in person. Yes, it's America's favorite because more people choose RCA Victor Eyewitness Television than any other kind. Choose it for clear, bright, steady pictures. It's America's first because RCA Victor has set quality standards for the entire industry, quality standards in all details that add up to finer television performance. And only with RCA Victor can you get, at moderate additional cost, all the benefits of the RCA Victor Factory Service Contract. Your RCA Victor television set is installed in service by RCA experts and top performance guaranteed for a year. It's the only factory to use service in television. So ask your dealer about complete details when you see RCA Victor Eyewitness Television. Back to the Screen Directors Playhouse production of It Happens Every Spring, starring Ray Milland in his original role of Vernon K. Simpson with Ted DeCorsia as Monk Lannigan. Those of you who care to do so may check my record with the St. Louis Baseball Club during the year which I speak. I'm known in the guidebooks, of course, as King Simpson. Suffice it to say that the St. Louis won the pen and went into the series. Mysterious liquid accidentally concocted in my laboratory had done its work well. But if the truth be known, I wasn't happy. My mind lingered long and lovingly over the blond and buttress Debbie Greenleaf. And it was while I pursued these thoughts in my hotel room one day that Monk Lannigan entered. Hiya, Vena Naziola. Hello, Monk. Hey, what's the matter with you? Me? Oh, nothing. Lonesome, I guess. Ha! I can fix that. Vena, no pal, I'll move in with you. No, Monk, you don't have to do that. Well, nice room we got here. What's this bottle on the dresser? Monk, don't touch that. That's what I use on the book.  Hair tonic. Oh, hair tonic. Say, who's the doll in this picture? She's the young lady to whom I'm engaged. It's funny you never brought her around. Oh, I couldn't do that. She doesn't know when her father doesn't know. What don't they know? About King Simpson. They don't know he's me or I'm him, you see? No. Well, her father, Dr. Greenleaf, wouldn't have let me go if he knew what I was doing. Let's you go. Where'd they have you? Well, Monk, I'm sorry I can't explain. But, look, you're my friend. I've got to see Debbie again. Now, she doesn't live far from St. Louis, and, well, I'm not pitching tomorrow. And Monk, I want you to cover up for me if I run up to see her. But tomorrow's the first game of the series. What's the difference? Jimmy Dolan says I'm supposed to rest my arm, so I'll be able to pitch the final game. And besides, I'll pitch better if I talk to Debbie. I don't know. Please, Monk. Okay. I'll tell you what you do. You go up there, but leave me the phone number so I can get in the hallway in case Dolan wants you, okay? Okay. My train arrived shortly after midnight, and since my time was limited, I resolved to go directly to the Greenleaf home. Stealing across the backyard, I stood directly beneath what I thought to be Debbie's window, and threw a few pebbles to attract her attention. Debbie! Darling! Darling, come to the window! Darling, it's Vernon. I love you. But I don't love you! Dr. Greenleaf! Well, I thought it was Debbie's window, you see? Oh, why don't you use the door? I don't want to wake anybody up!  Well, I can't tell you, I... Never mind. Haven't I heard from you? Debbie, you've got to trust me. My experiment has been a success, and so have I. We'll be able to be married, darling. When? After the end of the season. What season? The, uh, duck season. Well, soon explain yourself. Vernon's a success, father. We can afford to get married now. A success at what? Ducks. Simpson, after the way you've deluded us, it's a good thing you don't expect your old job back. Oh, for Dr. Greenleaf, I do. I'll have to have it back when the bottle's empty. Bottle? I knew it. He's taken to drink. Dr. Greenleaf, I've done nothing of the sort. Helen, it's worse. If a dimwit like you is making money, it can't be legal. Father! Well, look at the facts. He runs off mysteriously and comes crawling back mysteriously, talking about his money.  You can see it in his face. Father! Answer the phone. Yeah, criminal, that's what he is. Oh, Vernon, I don't know what you're doing, but I'm sure it's nothing wrong. I'm afraid your father wouldn't approve, Debbie, but believe me, it's perfectly legal. Hey, Dylan, sir, it's for you. Oh? Oh, thank you. Must be money. Debbie, you should have heard the voice on that thug who's calling him. I'll bet they're planning another crime right now. Oh, that's the craziest thing I ever heard. Well, I'm going to find out for myself. Father, that's Eve's dropping. Sure, come on. What about it, Monk? How'd things go today? Killed him, huh? That's fine. Now it's murdered. That boy will stop at nothing. Well, it's too bad I had to nail him at second, but I guess he's getting too old to steal anyway. Deeper and deeper. All right, Monk, I'll catch the next train back. I know Donald won't expect me to start mowing him down for a few days, but if he's worried... Yes, everything's fine here. Now, nobody suspects me yet. Right. Goodbye, Monk. We know you now for what you are. Murdering! Oh, mistake! Young man, for my daughter's sake, I won't ask the police to come to this house. Kindly leave immediately.  Oh, my. Oh, my goodness. Oh, Vernon, I still love you. Take me with you. Goodbye, Debbie Darling. Goodbye. Vernon, snap out of a window with the ballpark. I can't, Monk. All the music has gone out of my life. Music?    No job to go back to branded a common criminal. Well, the lover, Pete, will you get a move on? Poland's got to use you today. What with the series tied up free and all? We got to win this one, Vernon. Oh, very well. Monk. Yeah? Where's the bottle that was on my dresser? You mean your hair tonic? No, I mean the fluid that... Oh, yes. Yes, the hair tonic. I let it to a ball-headed bellboy. You... No. No, you couldn't. It's different. You ain't playing for the house of David. Monk, you don't understand. That bottle I... I won't be able to throw a single strike. Oh, this beats me. What do you need it for? Because it's... Well, it's a lucky charm. I'm superstitious. Well, I heard a rabbit's feet and elk's toes, but... Hair tonic, that's a no. I'm ruined. Now, look, Dwayne, and I'll tell you what to do. Leave everything to Monk. You get down to the ballpark and I'll scare up that bellboy. He'll give me the bottle back. I'll bring the bottle that you and Will will win the series, okay? You got to get it back, Monk. You've got to get that bottle. The series has tied up three and three, ladies and gentlemen, and here we go on to the top half of the fourth inning. St. Louis leads four to three. But the way King Simpson is pitching today, it doesn't look as if that lead is going to last very long. Now, look here, Simpson. Yes, Mr. Dolan. I don't know what's got into you today, but if it weren't for some pretty wonderful feeling, we'd be behind in this ball game instead of a run ahead. Well, maybe you ought to take me out, Mr. Dolan. No, sir, I'm going to take a chance on you. It's your ball game, Simpson, to win or lose. A lot of guys are counting on you. That's all.  Hey, hey, hey. Well, Mr. Lannick, and it's very nice of you to show up. Have you got it, Monk? Sure. Here it is, kid. Here's your bottle ahead, Tonic. Oh, thanks, Monk. And don't worry, Mr. Dolan, we're going to win this ball game. Never seen anything like it. Here we are in the top half of the night, and King Simpson has held Chicago Hitler's since the first to the fourth. As if by a miracle, he suddenly got his own fire by... And right now, there are two out. The count is three and two. There's a stretch and a pitch. Ladies and gentlemen, King Simpson, the winning pitcher has just keeled over in what seems to be a dead faint. What happened to me, Monk? That's okay, kid. You just fainted. Boy, you won a beautiful series. I did. Now, take it easy. The doc's looking after you. Oh, my wrists here. You must have fallen on it. It's pretty swollen. The doc thinks it's broken. He took X-ray. Oh? He'll be bringing a mind out.  How? You broke your bottle ahead, Tonic. Oh, my gentleman. You got the pitcher, doc. I'm afraid I have some very bad news for you, Mr. Simpson. You've suffered a linear fracture extending into the joint. I'm very much afraid you'll never be able to pitch professional ball again. Fine. It's all right, Monk. Well, that bottle broke. My pitching career was ended anyway. Oh, that screwy superstition. That don't mean nothing. There wasn't no head, Tonic, in that bottle. Well, you see, Monk, what did you say? Well, when I finally found the bell, I thought you'd already used the stuff up, so I filled the bottle with water. You mean...you mean no chemical? I'm really a pitcher, after all? Certainly. You really struck those bellas out? I did? Oh, no! You burned in my boy! Stuck a green leaf. Debbie? Oh, darling, you were magnificent. But what? Look, you were so upset about your girl, and our old man, I figured that could help. So, last night I found the same lumber you gave me when you went best in that time. Then they know everything? Why didn't you tell us you were King Simpson? Always knew you were a fine young man, literally sent me. Then you don't mind? You mind? Why should I mind?  When are you coming back to the university? Well, as soon as...right away, if you'll have me. Good! You've got a famous ball player on the staff now. He's a little screwy, maybe. Vynan.  Vynan, you're wonderful. Oh, Vynan. May all our children be catches. And him, a pitcher. You see what I mean? Baseball. It don't make sense. Jimmy Wallington speaking. You have just heard the last act of It Happens Every Spring. And our star, Ray Milland, with our guest screen director, Lloyd Bacon, will be with us in just a moment. Next Friday, one of Hollywood's most charming and talented actresses brings a favorite comedy performance to the screen director's playhouse. Our story is A Kiss in the Dark. And recreating her original role will be Jane Wyman with screen director Delmer Dave. And now, here again as tonight's star, Ray Milland. Ray, don't be surprised from now on if you get a few phone calls from the Dodgers every spring. Well, I wouldn't be much helped, Jimmy. It happened any of that magic head tonic. Besides in spring, my fancies turn to other things besides baseball. Oh, a likely turn to thoughts of love, for example? No, not likely, Jimmy. I'm a very happily married man. Well, a married man enjoys a little romance. With his wife, that is. Soft lights, sweet music and stuff. Sweet music, but definitely. Which more than ever can be enjoyed right at home these days thanks to the RCA Victor 45. I know what you mean, Jimmy. Like dancing to those 15 big name bands, RCA Victor's recorded on 45. Exactly. But of course, dance music is but part of all the music RCA Victor has released on 45. More than 2,100 tunes and more being recorded every day. Well, I can't say we bought that many 45 records, but we did buy both popular models of the 45 Changer. The automatic attachment model. Which we've plugged into our radio set. And which you can also plug into your Victrola phonograph or television set. Hmm, have to try that. Our other 45 is the little one with its own loud speaker, Mrs. Milan's very own.  Oh, there you have it, Ray. Even a mere youngster can play it. Jimmy, you can hardly miss getting those 7-inch records under the big center spindle correctly. And what's there to do after that? Nothing but press one button once and enjoy up to 50 minutes of music. And what music, Jimmy, is such rich tone. And there's the second great feature of the RCA Victor 45. Quality. The third is its low cost. 45 automatic players begin at $12.95. And 45 records as low as 46 cents. Those 15 dance albums you mentioned, Ray, cost $12.45 less when purchased on 45. And that's only 50 cents short of the price for the automatic 45 attachment. With record savings like this, it's no wonder all America is swinging to 45. Best swing I've ever seen, Jimmy. None better, Ray. Friends, join the swing to 45 when you buy your next record. Ladies and gentlemen, if ever a person really loved a motion picture, the director loved it happens every spring. Upon this film, he lavished the elaborate affection that springs only from the heart of a man who is absolutely dippy about baseball. Now I'd like you to meet him. The frustrated first baseman who's created such wonderful films as You Were Men For Me, Mother Is A Freshman and Miss Grant Takes Richmond. The director, Lloyd Bacon. Thank you, Ray, but I'm not really such a baseball fanatic. Well, Lloyd, you know how people talk. I wanted to direct it happens every spring because I just like baseball. Nothing wrong with that, is there? No, of course not. Doesn't make me a fanatic, does she? Certainly not. You've got to go over to my place some time. Oh, why? Baseballs, I've got thousands of baseballs. I understand, Lloyd. You're just a guy who puts his heart into the game. Unfortunately for us actors, you direct your pictures the same way. So, Lloyd, if you'll have me in another film, I'll do better than visit you and your baseballs. You will? I'll bring my bat with me. Good night, Lloyd. Good night, Ray. And good night to you, Ray Maland with Lloyd Bacon. Remember next Friday, Dane Wyman in A Kissin' the Dark was screened director Delma Dave, brought to you by RCA Victor, world leader in radio, first in recorded music, first in television. It happens every spring, was presented through the courtesy of 20th Century Fox, producers of the Technicolor musical Warbash Avenue starring Betty Gravel and Victor Mature. Ray Maland will soon be seen in the Paramount Picture Copper Canyon. Lloyd Bacon recently directed the forthcoming Columbia Pictures production, Kill the Empire, starring William Bendix. Included in tonight's cast were Eddie Field, Parley Bear, Ted DeCorsia, Dan Riss, Frank Nelson, Anne Diamond, and Frank Barton. It happens every spring, was adapted for radio by Richard Allen Simmons, and original music was composed and conducted by Robert Armbruster. Screened director's Playhouse is produced by Howard Wiley, and directed by Bill Karn. Portions of the program were transcribed. You are invited to listen again next Friday when RCA Victor presents Screened director's Playhouse star Jane Wyman, production A Kiss in the Dark, director Delmer Dave's


Welcome back to Kids Fun Science, my name is Kent and today's experiment is the Schroder stairs optical illusion. And if you like this video remember to please click subscribe and like. So the Schroder staircase is an optical illusion which is a two-dimensional drawing which may first be perceived either as a drawing of a staircase leading from the left to the right downwards or the same staircase only turned upside down facing the same exact way. And I'll show you in just a second. So look at the staircase right down the middle and stare at it and then I'll spin the staircase around upside down and then blink your eyes and you should see the staircase going down the same direction. We'll do it one more time stare down the middle, flip it around, blink and you see the staircase is changed which is pretty awesome it's going the same direction. So the staircase it can be perceived in two different ways depending on whether your viewers consider A or B to be the closest wall. So I marked them A and B and so when you see I flip it around they actually switch walls and the staircase still goes down the right way after you blink your eyes they're pretty incredible. If you like this optical illusion experiment please remember to click thumbs up and subscribe and thanks for watching.