Hey everyone second day of CCC camp Here on playing stage. We have our next talk right now coming up with Reina as a huge applause for Reina first for all our speaker Reina will talk about blockchain and what's currently ma not so good or what's maybe not so good in the future with blockchain and yeah, so in the end we will do a short Q&A and I will come to you with these microphones so you can so we have your question on the recording as well and Yeah, that's pretty much it so Allah a bomb welcome and have fun with Reina and yeah blockchain and Proof of ignorance Okay, hello everyone. I think now the slide will come up Soon that's the magic of technology. I guess Yes, so this is one slide and it will stay like this as I've mentioned in the program. This will may have Some grains of a rant so you can listen to me and there's nothing to see there Okay, so blockchain proof of ignorance. I chose the subtitle title with liberty and justice for some maybe you know The book by Glenn Greenwald. I think from 2011 where he analyzed the US system Where in the opposition to the Constitution where it says with liberty and justice for all He said well the system is gained and it's gained in the way that there's liberty and justice only for some And I want to make the point that this is basically the same with blockchain. So first to me My name is Reiner I'm a computer scientist researcher at the Weizmann Institute for the network society and I'm also here with fifth the computer professionals for peace and social responsibility were over there in the village and I've been talking about blockchain for more than two years now and usually about the assumptions and What problems should be solved with this or what problems cannot be solved with that? If this talk is too witty or too cynical for you, I hope you excuse me as I said It's supposed to be around so what I'm talking about is on an abstract level a blockchain as an emancipatory and autonomy technology which gives power back to the users and Especially because it's it's supposed to take away the intermediaries I think you all know what that and I'm I'm pretty sure that a lot of you have a very Critical stands on blockchain right now So probably my conclusion might not be new to you But what I try to do is to give you a larger reasoning why? Why this feeling you might have or why those why those? Insights you have from a technical technical point of view are also valid from you could say maybe more social science point of view And I will concentrate more on blockchain as emancipatory and less on the supply chain management things although we can It's only one hour We can move this topic to the Q&A if you're interested in that why I think that's not a good idea So this talk will have three parts first. I want to talk about industrialization and division of labor then I want to talk about blockchain and Autonomy or emancipation of the of the end user and then I will close with some final thoughts and then we'll have the Q&A session So first I want to talk about industrialization and division of labor. Well, welcome. That's my Trojan now You have to listen to this all okay, so let's talk about division of labor. Well There has been the hunter-gatherer society agricultural society Let's say maybe from 10,000 years ago where people started staying in one place and you know the hunter-gatherer gatherer thing There was no Specialization in the way that we know it now Certainly there were roles in those societies in the villages But not in the sense of how we now in those industrial societies We have like very specific tasks even maybe broken down to one part of the screw Which is not even the whole screw to make that for example so the next step you could say is industrialization industrialization where you would say maybe you could See the starting point the mid of the 18th century 1750 somehow where some people would say The start with the steam engine and such this is usually the tech narrative But in social science there are also other voices who say industrialization actually came about because of mainly a reorganization of labor to Tarunino our writers that wrote about this So that means you could have had industrialization without changing technology just because you reorganize And split up labor and then distributed to different people. So it's you know, that's just the other end Which would be a totally non-tech narrative Um, well, of course the truth that is somewhere in between it's usually intertwined People create technology then technology creates how people interact with each other and back and forth So it's oh it's as usually I think a mix So but what changed? Well at first I want to look at the workplace Like Riese somehow distinguished three dimensions where work changed first. We had standardization So we could measure products we could like Measure in the physical sense but also in terms of quality so we can say if we know Um the products are standardized then you can split this up into a chain and then you can say okay, I replaced this part or I use another part because The interfaces are somehow standardized Then we have specialization So the creation of products has been broken up into small and smaller steps From making the whole shoe into making the soles and the you know, the top part and the laces and everything So split it up Um to specialize and then have maybe higher quality and then you know And the third one would be automation So if you have the specialization and the standardization you can actually start Letting machines doing part of the work In the case of the steam engine was the physical labor that was being replaced um Now we could say maybe uh now the like the the mental label is uh is being automated as well By the use of computers, but this isn't this is not how it started somehow So obviously society changed because of those kind of production methods um Well with the specialization the increase In a degree of details for each step If you're marxin you would say oh, this is the start of the alienation of the worker So if you're not really You know building making the shoe and selling it to people But you're just using the laces you will never see the happy customer buying the shoe with a beautiful laces So you're somehow alienated from this the things you do and uh not getting any social feedback somehow so Hence society became more complex because of course You have to organize this kind of labor and this kind of you know I have the parts and then you reunify the parts again you have to so so a special um new class like the bureaucrats were Created somehow, you know the people with the ties who just only do the the organization of labor um And in the same way the products and artifacts also became more complex If you look at it now even shoes have this kind of you know The parts where the air is in and then the other parts where you know protects you from from rain and whatever I i'm not wearing shoes. So maybe that's okay um so um the alienation started from um People from their products But also people from each other and people with larger organizations where people work Where you don't even know really where's like who's the management and all this so everything gets more and more complicated because of splitting up all the steps so um Sociality somehow definitely changed from communities to society. What does that mean? Well in the community usually you have individual exchanges between people who are seen as people so you have Your neighbor is not someone who provides a service to you But it's your neighbor with their problems with you know with the whole personality somehow So this is somehow how villages somehow worked and if you look around in camp as well um You have the villages where people know each other and with people It's not really the exchange of products, but it's more like being there together as as a group but society In the opposite is somehow Characterized if you want to follow Tony's on this by the functional exchange. So if you go to the bakery um, you're actually not that much interested in You know how the life is going of the person selling you the bread Maybe there might even be just an A machine doing this for you. So you're only interested in the functional service that person provides to you So that's somehow Someone made the shoe and gave it to someone else and in the end you just go to the shop Here's the money. I want to have the shoe. So the interactions somehow dehumanize and get very functional So this is kind of the the switch from community to society as you would say So that means You're now we have a continuous exposure to incomprehensible artifacts. They might be technical or not It's the same with if you think about As I said, you don't even know maybe Maybe usually you don't even know where your bread comes from You know, if you go to a organic shop and they show you, you know, this is the bakery You can even go there But this is not really how at the moment society largely works and all those complicated products If you think about cars computers condoms water socks food in all of those products, we are We're not experts So we go to a shop and we buy something and somehow we have trust that it will not poison us It will not, you know, hurt us or anything like that so but also What also came up As a change is More and more power differences because not all actors in the society game are equally powerful Of course the individual if you're in the community If there's a problem, of course, you can somehow deal with a problem or with a person you have a problem with or Anything and if there's if you can't solve it, maybe you go somehow one layer up But you also know though this person So it's maybe the the elderly person in the village or something but you still know each other But now with large organizations if you have a problem Well, you get to the customer complaints and they all think our problems are really important to them And they will get to back to us as soon as possible You know, you don't really you don't really know what's happening You're just interacting with the machine if so to say and of course those large corporations might it be BMW or facebook They are very very powerful. They define How a facebook profile looks like somehow what what you can choose? How to present yourself, right? We had this we had this problem with Let's say gender facebook says there are only two genders. Well, this is what you can you could choose in your pulldown menu, right? You can't change what how How a profile looks like you can maybe fill in your famous movies or something But that's that's you know, so the structuring of society is completely taken over by those Organizations it must it's not necessarily bad, but I'm just saying there is a difference So but how do we deal with the situation of those power indifferences and those largely not understood Systems and and complex interactions and also the products. We don't really understand. Well, they're basically Two two approaches it's like two extremes on the scale I would call the first one the libertarian approach and the second one is the collectivist approach Well, the libertarian approach says I would like to call it the warrior mode is kind of I have my individual responsibility and I want to have the power to live my life as I please and if I want something a product or something changed Then I have to learn about it and change it myself That's kind of maybe in this community it would would be like, okay, there's surveillance and everything So what do you do? Well, you encrypt your emails. This is what it can do You acquire the knowledge about it security dot data protection all this and then you start doing what you do and this is kind of the the you could say Maybe crypto or anarchist view Encrypt your stuff and your friend stuff and then you try to stay out of society You somehow try to create an enclave where you in your warrior mindset can kind of fight society Because it's not like you want it to be The other approach is somehow the I would call the collectivist approach It's somehow I would say maybe in computer terms protected mode. So we have some Collective responsibility that society is somehow shaped in a form that not everyone has to be a warrior all the time so Those power differences have to be somehow Counterbalanced what we made up for this is some kind of the idea or the most positive idea like a state where you say, okay People pay taxes and then maybe the the weaker ones of society They get some kind of support the stronger ones have to pay more taxes. It's an ideal world. I know it doesn't work like that But that's that's somehow that's somehow the idea So that there's an a collective system in place that somehow Balances again those natural imbalances So if we have If we have like those two modes of of operation now we can think about emancipation and autonomy It's somehow autonomy the opposite of heteronomy Which means like to be controlled by other people But to to take your life and to head to take your decisions into your own hands to be able to do this So you want to live freely and independent? Um from coercion but even from sickness somehow right because we all have different health Uh prepositions, of course, there's the part of how we live our lives But of course there's the part of how we're born and and all those things so in the first case well The first case. I mean, uh the libertarian If you want to live free well, then you need the power and the resources And some critics even say you need the luck, you know, some people are born with passports with more Possibilities and other people just had bad luck with maybe even no passport So but this is something you have to deal with yourself Right the libertarian approach the second case the the collectivist approach is somehow The group of people the society somehow Has to come up with a solution that the society and the environment Should somehow be prepared to somehow carry the power the powerless and restrain the strong ones well Some critics say it's only about raising the powerless But that doesn't really work because the means to distribute are somehow limited. So if you want to Support the powerless, of course, you have to take power from someone So it's it's you could even say it's a zero sum game So if some people say well the problem is not that there are so many poor people The problem is that they are not enough rich people Well, it's with one one amount of money Of course, you can't make other people rich without taking money from somewhere, you know, it doesn't it's connected So just an example For this kind of the libertarian approach and the collectivist approach if you think of Maybe you have the freedom of movement in a city with a lot of bridges Like Berlin for example, Berlin has more bridges than Venice. So let's take Berlin. So the libertarian approach What would it be? It would be well, you have to repair the bridges all the time You have to learn how to swim. Maybe you have to buy a boat Maybe a big car that you can actually drive through those areas where the bridges are broken Or maybe you have strong and important friends who somehow arrange things for you Well, the collectivist approach would be well We have to make some organization create organizations whose responsibility is To take care that those bridges are in good conditions because not everyone is a bridge maker, right? So the main target of this organization is that you can actually exercise your freedom for free for free movement Which is based on the bridges being in a good condition So that means just to say well, you have the freedom of movement the next question should be but what are the preconditions? Well, if there's a lot of bridges then the bridges have to be okay Otherwise this freedom will never be exercised or only be exercised by the powerful ones, right? So that's kind of the libertarian versus collectivist So now let's talk about blockchain finally Especially when I say blockchain I include smart contracts and the like And what I will not talk about is permissioned or private blockchains Because to be honest, I as a computer scientist and probably as you somehow are as well Permission or private blockchains of course are databases Somehow but really really slow and inefficient databases because of course if you say, you know We have we want to have a system where everyone can participate and then you say, okay Let's have it private or permissioned Again, you have a power entity that decides who plays the game or who doesn't so I don't want to talk about this So I want to talk about the the public immutable distributed ledger. That's the real thing. This is the only thing I would consider a blockchain So the promise here now is with blockchain. We want to have money without banks We want to have consensus without notaries. We want to have a world without intermediaries And we want to have a society without the need for trust If you think back to what I said before this would be the trust into an organization that that organization actually takes care of the bridges We don't want to have those in between things. We want to have, you know, only direct interactions Exactly so let's look for example at a bitcoin and autonomy for this matter but this can be used for for A lot of blockchain approaches somehow, but it's basically I would say the still the largest maybe you can add ethereum as well application Of of this public blockchain, which is actually in use Well the idea and now I make this as a concrete example But as I say you can make the extra abstract view about this yourself Well, the idea is well people should have their own wallets and it's decentralized There's no central entity who can meddle with with the numbers or anything And the idea is well mining is done by everyone. It's also decentralized So that means in this if this will work like that, of course, it's a good idea Because then you This is this is one approach to somehow decrease those power imbalances by just saying there are just no entities who have power So the system should somehow reorganize itself because everything is centralized a decentralized and stays like that Well, but of course if you look at the reality People use exchanges a lot a lot of you know, the majority of people uses exchanges and not have their own wallets Because it's easier to transfer money and everything but if you look at it Also in the somehow daily use it's mainly the it experts and the people who know what they're doing That are having their own wallets in their computers in their Mobile phones, but everyone else actually uses exchanges And the reality with the mining well, it's done by some big players if you think of bitmain It's somehow around depending on your on the estimations 60 of the hash power Somehow so the mining itself it also became centralized because of financial incentives because of other reasons But we have again a centralized system because there was no No Like built-in system To keep it decentralized somehow Well, at least it is still public, right? So that was those were kind of the the the promises But why are there those problems? Why why do people use exchanges? Well Obviously not everyone is an it expert only those It expert they can have wallets because if you have a wallet, what does it mean? Well, you have all your valuables on your computer You have to understand when to update you have to understand how to secure your machine And all those things that are necessary around To actually make use of you being able to control the money yourself And if we look at the mining for example, this is a another point so even Even if there would be a hundred nodes and 19 nodes A hundred nodes and the system would be technically decentralized it could be that 19 nodes belong to one person So at this point you would have a technically decentralized system But the power analysis would show you that there is again Again there's a power center and this cannot be prevented by the technology itself, of course, right? So this is that's a so we somehow have a decentralized world already using like the most The most broadly used blockchain system I will not go into details, but could it be otherwise? and So let's pretend it would be otherwise so people would Would have their own wallets and everything like that. Well, look at some random cases so You have an insecure computer your money was stolen. Well in the old world in the banking system. Well If there's anything happening, you know, uh, like like It's it's not always the case But if some of the banks go bankrupt There is a system in place that someone says, okay, if one bank goes down it will be supported by other banks So the individuals Usually that's the ideal world will not use their money because there are mechanisms in play in place That support comes from other ways. So it's not it's not about The individual now having to suffer that some banks went down. I know 2008 complicated, okay Um, so sometimes even if you have credit card fraud and whatever Usually there are some kind of kind of insurances in place and maybe it's a lot of paperwork Um, but at this point somehow You get back what you lost Or if you say for example, you have made a drunk transfer I don't know if it happened to you.  That's the most obvious one, but maybe there are other reasons why you were forced to do this Um, or maybe you ordered something and the damaged and the goods delivered are actually damaged So how do you how do you like revert a transaction? Well, of course, it's it's mutable. You can't revert it somehow So in this case in all those cases what I just outlined the money in this example is gone So as as I say again the old intermediaries could somehow tap into the jurisdiction system and say, okay, maybe You were forced to do that. So that's why this thing has to be reverted and so Usually if judicial cases come before court, then the whole context will be taken into account If there has been a contract The contract isn't expressed of your will So that means If there's a dispute then before court this has to be negotiated Was it your will and whatever and whatever if you have for example smart contracts? What counts is what the program said it might not have been what you wanted, but this is what counts Um, or maybe you have a pension uh a pension smart contract and you get like in I don't know 50 years or so you get all your money you saved and everything Well, what is what if there's a bug in your smart contract? And I mean we are all somehow closer or further away from programming Um, sometimes I wonder why planes actually work But you know if there's something if you want to write code that should still be working and valid in 50 years Good luck with that The same would happen if you say let's for example Ensure a car and let's attach a smart contract. So if your card's damaged then you get to you know You get your money back Automatically well, of course the first thing the insurance would say is well How do we know that the car was actually damaged then you would say well But there were some sensors and so this has been reported back into the blockchain and they would say yeah But are the sensors actually okay? We don't trust you. Maybe it was yourself So maybe can you add some more camera proof that it was not yourself hitting the car? You know and suddenly you see it's not about oh there's a damage and that's why I get the money back It's about what happened who did the damage to how What's the whole context of it? Was it really an insurance case or is it a case of fraud? But this is nothing in the scope of a blockchain that just saves what is So in all those aspects what's up with the autonomy it somehow seems That if you take all this into your hands And you secure your computer and you have everything around It seems like you're pretty busy all day keeping this system up and running So it's quite a busy thing to be autonomous and of course it is and I'm not saying one should not strive for it I'm just saying we should reflect on the Necessary preconditions to actually be autonomous. So I would say I would say how free and self determined Can a person be if you're constantly thinking about not being poisoned not losing your money not being hacked Not being you know killed and whatever all all those things. Well It seems like quite a lot of regulation and intermediaries have to be around For us actually to be free and autonomous And that's a pretty pretty interesting thing If you take the blockchain approach which says well, let's get rid of everything around and then you can finally be free And now it seems like and of course, I'm exaggerating a little bit Now it seems like all this regulation and we can certainly discuss about this is actually a precondition for being free And we suddenly it's it's totally the other way around then we're not talking about the individual That tries to be free all the time, but suddenly we're talking about bigger structures Creating the preconditions and we can do this in a democratic way and whatever we want to do this But this is about societal negotiation not about coding and not about hacking and not about it security It plays a role, but this is not the starting point And again, I mentioned the examples Think of condoms right if if you would have this kind of your your Responsibility for everything around you. Well right now you go to a shop You get you get those and you're pretty sure well according to all we know you have a certain percentage that things work Well, but in this kind of blockchain thinking you would say well There's a shelf and you have all kinds of and it's written on there You know, this is kind of 60 safe, but it's cheaper this kind of 90 but this is a little bit more expensive And suddenly you see wow now suddenly you have to be a latex expert And a rubber expert to to see which one you should actually choose Well, and if you don't have such a big income well bad for you, then you have to buy the cheaper ones Right, so suddenly you in all those aspects you see how the environment somehow shapes how free you can actually be And it's the same with food with breaks with water You know, it's the same with car and brakes I'm also not shaking my brakes all the time because there is there is a system in place that somehow says if your brakes Do not meet this minimal standard You should not go to the road and this is not about myself Because I can be sure that all the cars around me also had this check You know, maybe you don't trust the drivers, but if you're honest to yourself You trust the drivers if you're on the motorway or even if you're on the bus If you would think things will go go wrong regularly would not take the bus So you have this kind of trust all the time everywhere And now I find it pretty interesting to say well, let's use some Let's apply some kind of technology that says well, let's get rid of all the trust If you look around you and maybe today what you will do all day Just make this example to say what would I now do if I would not trust those people around me? how How much effort it would be all the time to secure everything And this this would be I would consider this a very unfree world So what I'm just saying and this is kind of maybe the the the extreme Thesis here we can discuss later on without those safeguards autonomy is not possible at all And it's not possible in any meaningful way At least not for the majority of people So that means Those blockchain individualization efforts are actually working against the autonomy Of everyone who's not an it expert And this is this is a pretty pretty dim vision if you think about it So that means those who don't happen to have it as their hobby or their profession Well, you better not be old or weak or busy have other strengths or anything to guard your values and live your life Right, that's kind of the thing So what I'm saying somehow The the the the the thesis I'm putting out here is somehow Those kind of individualization efforts Of the blockchain are actually somehow a rollback into medieval times where the most The things you think about the most is how to secure yourself and how to be in this kind of warrior defending yourself mode all the time And to make it more more Like more imaginative you could say this is kind of hiding your own money under your pillow and then thinking Okay, how where should I hide that people don't find it? And I would just say this is neither freedom nor autonomy So now we finally understand why why it makes total sense for people to use exchanges because If their computer gets hacked. Well, okay, it depends on did you store your password and everything But somehow there is someone Taking the job for you to deal with it security with all those measurements to keeping the software up to date Which maybe most of the time they don't but that's a different problem Um, but I think you see you see what I'm saying here It's not that people are actually lazy to use exchanges It is just a world that uses division of labor and what I would say now is that All the talk of tech people about the autonomy by blockchain can only do this because everything else does not work like that So everything else Creates that much free space so they can walk around and say hey this you know spend your time Thinking about it security, which I don't think this should be a reasonable expectation for a whole society that includes everyone So what is blockchain good for well, this is a kind of a funny thing I've been to many blockchain conferences And it's actually good as a business case Well, you create a product and if you find a customer. Well, that's good It doesn't even say if it works if it's a good solution or anything This was kind of what I what I noticed in those more financially oriented Um Blockchain conferences if you look at the like the top five examples for blockchain news If you could you could solve all of that with a normal database, but blockchain is a new thing So you can sell it and when I question people afterwards in panels what they said is yeah Yeah, that's true. I don't I don't care about the technology if you call it something else My task is to sell it. That's it. The use case is to sell it To transfer money from the old intermediaries to us You know, that's that's that's the idea So that means if you find a paying customer, well, you're succeeded And maybe uh, you could also say it's some kind of um, esoteric thinking Where it's psychologically interesting why people actually want to get rid of those intermediaries and be free So this is more psychologically interesting and I totally Understand the need for that. But what what we could say that for example Bitcoin and this would be my interpretation is not a call for You having wallets ourselves, but it's a call for the democratization of the banking system and that's a whole whole different thing And if we widen if we like look around what other use cases there are let's say Supply chain management to the all those kind of I can prove whatever, uh, you know, I can prove things to other people um Usually the examples where blockchain is being applied to or or Is is wanted to be applied to those are usually the societally hard questions So if people propose to use blockchain for something it doesn't say you something about blockchain It says something about the person what that person thinks is the hardest problem So that the magical blockchain will just save it for them. So um, as somehow leon kaiser phrased it You could see the blockchain as a rorschach test So you say now we have this nice technology. What do you want to solve with that? And then it's interesting to hear what those people say to you what they think their biggest problems are Blockchain will not help but now we maybe understand better. What's what's wrong in this organization? Okay, and so just as a as a comment maybe if we're now we're heading into into the discussion somehow um If you want to have somehow supply chain management and you say oh, let's let's have a proof where everything came from Well, who puts in the data in those in those blockchains? Well, of course, it's the suppliers So the blockchain actually just records What they said would happen you can still distrust them and say well, you wrote wrong information in it What the blockchain just saves is what they said So again, you see this is this is not where it actually helps Um to apply this because now you just have a very very secure place to save Alligations and not truth Okay, and maybe as a last example, I heard I I heard It's quite interesting if you look at a lot of situations Where a blockchain is actually marketed to work Then usually It's somehow the same as if you would say well, we'd like to deconstruct this house Let's drive against against the walls with an suv and eventually the building will collapse it works But this is not the technologically best solution Okay, so now, um, I think we are ready for q&a and thanks a lot for listening Yeah Thanks a lot reiner. Thank you.  Not really not really. Yeah Looks pretty grim. Okay. So we are ready for our q&a Um, um, if you have questions, I'm coming to you. So Please wait when I'm here so Hi there. Thanks for the talk and for the for the critical points. Um I think I mean you are absolutely right With with your analysts and as this in one thing we do need to have these kind of organizations structures Social contracts to safeguard us and in order to be able to really Yeah execute our liberties But the point is what blockchain also Enables us is to organize these structures in a more democratic way So if you say bitcoin is the kind of democratization Of the of the banking system in principle any dao. So a decentralized autonomous organization can be a democratic Or transparent implementation of such a social Organization social contract that acts as one of these safeguards. So for example, you can build a decentralized exchange You can like implement some future key liquid democracy voting things and and I think in in in your talk in this kind of grim outlook I feel you underestimated possibilities of daos I mean, they are only starting to get useful For the everyday user because well, mostly you have to be a tech expert to also participate, but this is actually Changing at the moment right now for example day before yesterday There was dao fest in berlin and and people talking about it. So I just wanted to Also give that perspective and I wanted if you I wanted to ask if you could comment Yes, sure. Um, yeah, that's actually a pretty good point. Um The point here somehow is first one maybe I expressed in the wrong way I'm not saying that bitcoin is a democratization of the banking system What I said is the bitcoin in itself. It is a criticism that Once we democratize the banking system, we can get rid of this kind of Things again somehow and I think you're right. I mean a lot of organizations somehow have Um Listened to all those criticisms. There are still some diehard fans of this kind of ultra liberal as the poach But with the dao, I mean, I would like to look into into the details of that. I mean the last big Dao that failed crazily with you know with this kind of uh with those Bankruptcy and taking out the funds The interesting thing was that was because of a coding mistake So what what do you do? What kind of safeguards do you have if your immutability if the things you wanted to do with the dao Was actually, you know, weizmann said the computer will always Do what you told him that but that might not have been what you had in mind And so this is if you but if you now say let's create those daos And they are fully autonomous, but there are ways of Um to have interrupts and say, okay, let's revoke this transaction and do this again Or you know all those things suddenly. This is not what the blockchain promised Right, so this is this something but I'm I'm I'm uh, I'm happily looking for for other approaches Um, and what I would say as an example I would not say, you know get away with this technology If you for example pay attention to fair coin where they said, okay, let's first create The social environment Where within which This kind of blockchain approach could actually work. So you have Social negotiation about the trends about the The the trading ratio you don't have proof of work, but proof of Proof of cooperation. So those kind of notes who will be next Calculating this is done by social negotiation. So this is something But this is not the pure the pure wisdom anymore. Um, and also There's maybe something I would like to add What I think what we should not do is to throw this out the whole window because somehow Many people who do not really understand what blockchain does and what it cannot can't do But it seems like a lot of people now listen And want to change something. So if we know, okay, that person had blockchain Maybe means digitalization or something with computers. Well, we can also use this wave and just say, yeah Yeah, we apply something and this is called blockchain, but it's not public immutable ledger But it's a different thing. So this is something we can use and to somehow get away from this pure Understanding and then get towards a solution that does not neglect that society needs trust but somehow It takes this into account as well. So this is yeah Thanks I'm also much more optimistic as the previous person who who talked. Thanks So about the security problem, for example, back in apiarchy. They are now on ethereum and soon on bitcoin smart contract based wallet where you don't have to backup keys Where you have recovery schemes So this How did you told it? Regulators and stuff in place They will be over time. I hope implemented in smart contracts and ways to also to make them upgradable in a kind of safe way So I'm still much more optimistic Okay, thanks for the comment. I think there's one thing we have to think about If this is being done and implemented we still I would still ask Who decides how the show code should look like what are the rules? What what is seemed to be a good solution for revoking or this kind of recovery scheme? I think there's a lot of politics involved in there And this is if this is being done in a democratic way, I think I would I would also see okay. Maybe there is a way of actually improving something But this is exactly the complexity that comes back in again to discuss about code who will be Who has Read and write writes to the to the repositories and stuff like that. I know about direct follow-up. Yeah, sure. So The the fact is that you can choose what Smart contract you are participating to so there are different set of conditions and you choose yourself Which one you opt in and you can try many Okay Okay, then I do the direct interaction with the direct interaction I think that's a good idea But I guess the problem that has to be tackled then is how do how do you make transparent? What are the properties of those different schemes so that non it people would actually understand and are able to choose the right one for them? That's the classic problem with Investment or all this. I'm not saying it's unsolvable. I'm just saying then this is where the complexity Comes back in and if if there's a good solution for that. I wouldn't say it's it's not possible I'm just saying it's much more difficult than like throwing out this the code And now you can choose and that's the solution to choose because choosing is like transparency You have to be able to Understand what's being presented to you And then you can actually make a choice. It's like it's like with those Informed consent and data protection. No one's in for it's really informed about anything And but still we we say oh, but it's your choice and now that you consented we can do everything We wrote in those 160 pages, you know, this is We have to think about what choice means And this is yeah as a as a basic thought for this Hey, thanks for your talk. I think I disagree with most of the points you made Also shameless plug. We will host a debate night tomorrow at the 402 payment required village Which will probably cover similar topics. My question is If bitcoin or systems like bitcoin actually reduce the autonomy or are very hard to use How come that more and more people around the world actually massively benefit from that people who live in oppressive governments Like venezuela iran china people who just want to buy the medicine they need or normal people who just want to save Yeah, that's actually a pretty good point Um But if you look at I mean in venezuela the cryptocurrency story was not really successful I mean they didn't use their own but okay anyway, but the point is I guess the point is at what I would say is This might be a temporary fix for a totally different problem because If you look at this people in oppressive regimes Of course, they spent their whole day resisting the oppressive regime And so bitcoin like getting into this and trying to get medicine. I totally agree with you, but if the use case is um That it works in oppressive regimes Then I would say this is a very narrow and a very justifiable use case But I don't think it's a general theory of society to say It's it's being used a lot in oppressive regimes. So it must be a good thing in a free society to use so If if this is part of your of your fight for freedom, then I would totally agree and I would also encourage people to use it for those reasons totally, yeah Well, just as a comment for uh, like Ultimately with a with a blockchain and with smart contracts on it. You have a way to transparently Kind of enforce a social contract. Now. Let's like let's keep bucks and stuff Sites and fail saves. Let's say this is in to some extent an engineering issue Then you can use these blockchains to really enforce To enforce social contracts. So then that means it's actually a possibility to go Beyond oppressive regimes which offer some kind of social contracts to let's say to their citizens or some groups like a facebook to their users or whatever And but this is a way to transparently enforce it And with a perspective why everything is focused so much on defy decentralized finance? Well, ultimately, we all have to agree that money is the largest social contract that we have at at the moment and So like just a final example two months ago A dao launched, which is called the dx dao, which basically governs decentralized exchange protocol and there well, basically the dao itself is on chain And the dao itself has the key or the possibility to change the parameters of that Contract and these such a para meter change that needs to be like proposed and on chain people that Are part of the dao can then change these Parameters, okay. Now. It's the question like the reputation holders or the people who can vote How are these voting rights distributed? But this you can also do in a kind of meritocratic way by like Some okay, you have some initial set of people who somehow got the other in the first place But their incentive is to kind of like distribute voting power to people who actually do things So they're implementing a meritocracy and so so I think I think there is possibilities and I think well it's very worthwhile thinking about these things and and and Like trying to let your mind flow flow free and not only taking the liberal libertarian perspective I think for taking the socialist perspective on blockchains and decentralized organizations. There's a lot of potential Okay, there's one person agree. No, and it was also. No, wait, wait, wait. There was there was also There was also someone with a question up here front Um here you yes, exactly and I want to answer and this um if the idea is somehow to Reflect and represent the democratic negotiation process within the whole system That's you know, that that's that's an interesting approach And if the all those criticisms I mentioned are taken into account I have nothing against that of course I would say this is this this is then a good a good way Um of like trying to tackle the problem I'm just saying all the things I mentioned needs need to be taken into account and I would be very curious to see if What I presented to formalize this and put this into code If this is more or less complicated than actually You know thinking about society this but I would leave it open. Definitely. Yeah Okay, yeah, all right next question Thank you so much for your talk Um What I already thought about it. For example, the you at the european central bank And just could bring some euros and so on And I think this could maybe a problem if for example, the government changes or for example And someone is elected That does not care so much about the The money and so on and just brings out the money um, I think That that could be maybe a problem that we that the whole trust is is on the central bank For a certain currency and and I think that's a little bit problematic. Maybe for for future Maybe it's okay for now because we live in a good society But how can we guarantee that we we always Have this good condition in our society Because things can change. Yeah. Well, of course, I guess that's the main problem We can't guarantee that and that's the point. I mean In the same way that that's why I argued somehow that uh, bitcoin is the the call for democratization I mean the whole idea of the modern understanding of a state is somehow to limit centers of power To discuss how powerful those entities should be to provide the services But not more. Of course, we have to discuss where exactly this point is But in the end it doesn't matter if if you have a group of five coders Who maintain, uh, you know the the bitcoin code or whether you have the central bankers who can decide on this It's it's just the same Centralization of power. We do not we have to prevent somehow. That's why I agree with you, but this is not a technical thing so, yeah I would also agree with a lot of criticism you had, uh, but I would uh Say the conclusion should be a different one. The conclusion should be challenge accepted and also like really what you said Like with this wave is going on now There are so many extremely important Experiments that are running and if the whole thing explodes Shit on it, but it's all this what we learned and all also this Scientific approaches and and like the shrapnel if if the rocket explodes Let's take the shrapnel and let's take all the technology and gather the pieces build something new You know, like I think there's good experiments running now. So but we should also be careful. It's a sharp tool And that's also like for for regimes Like they have real problems. That's why they need the tools now We might have this problem in the future and that might be a tool that is growing that we can use later on, you know, just Yeah Okay, then um as a comment to this I would I'm totally happy and I'm always amazed with what kind of Ideas people come up and I usually get this kind of okay, but let's let's try and imagine and let go and all this I get this in conferences as comments quite a lot. What I'm just saying is um Maybe start a little bit smaller than saying the whole society will work like this and everything will be rearranged Just to take into account that this technology comes into an existing world Where all the systems that are there They might not be good, but they have a history There's a reason why a bank works like that. It might not be a good idea But that was a reaction of previous systems and that was a reaction to previous systems. So if you want to Overhaul the whole system. I'm I'm all up for world revolution. You know, it's it's a good idea And if it needs blockchain what I'm in that's fine. But what I'm just saying is we or like The blockchain scene should not jump into those societal discussion and say we know better And you know, you have been thinking about political theory for the last 200 2000 whatever years and we know how the society should be reshaped and let's have some experiments You know all this I'm just saying we should have those experiments But maybe start a bit smaller than leaving people on the way who are maybe not that tax-savvy as we are Okay All right This yeah, I think this pretty much was it Thank you for for your participation. Thanks for your questions And again a big applause for Reina here on stage


The short of course, it's not right. Do you realize it's a free phone? Uh, no. Just, let's go ahead and just put that in. Let's go ahead and get that into the final draft.  We like both of those. Why did anybody have it all done? Now they're meant, well, if you had it almost all done, it almost goes straight into the report. So there's not necessarily any great shakes of work that's been lost. All right. We were looking last Wednesday at some way to look at systems of particles. We've spent, we've spent all the first weeks here. Oh, by the way, don't forget, five weeks left. And it goes by very quickly. So if you're missing work, or postponing things a little bit, you could, could be sorry. So get the stuff done, not just this class, any class. It goes by very, very quickly. Before you know it, we're going to be on the beach in our Speedos. All right. So we've been looking at systems of particles. We started that yesterday. What we found out was, was kind of nice. Well, we were looking at very, very simple collisions. And we're going to look at more and more involved in elaborate collisions as we go. We were looking at simple collision. I can't remember who was driving behind me. An awesome red sports car got hit. A couple things from that. One of the most important things we found was that even though each of the objects, which we've always been taking to be particles now anyway, each of the objects very, very clearly undergoes an acceleration. As anything is going to happen in the collision, there's going to be a big change in speed. The car going behind that was going faster is going to slow down quite a bit due to a force that car felt from the car in front. However, we found out that we could analyze almost the entire collision without ever even worrying what that force was. That's what we came out with on Wednesday. We were able to take a look at the whole collision. And by that, I mean, find out what the after-collision velocity was of the two vehicles. We assumed for at least the timing that they collided, stuck together, and then therefore we're doing the same speed. And we found out when we looked at it that way, looked at it as a system, we could ignore what these forces were, just look at the velocities before and the velocities after. Actually, we have to look at it a little bit more than just velocities, wasn't it? As we took these to be a system, that meant these forces were internal to that system. Thus, they're always paired together and they're action-reaction-pair and they canceled each other so we didn't even have to worry about things. Right? That's what we did on Wednesday. Long time ago, bless you, long time ago. Everybody was here except for Samantha. Amanda was here but Samantha wasn't. Since those forces were internal and during the collision, those were the major forces far and away, more involvement of those forces than any other, then we could make the assumption that during the collision, there were no external forces. What did we do with it from there? Do you remember? I didn't derive that because of MA. I never derived it. God gave that to us. That's on the 11th Tablet. Moses dropped it on the way down. Newton had to discover it. Actually Galileo. Now what? Since we make a system that makes all these forces internal, unless they are equal in opposite pairs, they cancel each other, we didn't have any other forces going on. Remember, we're only looking at the instant of the collision. We don't talk about any of the skidding afterwards. That's a whole different deal. Since there are no external forces, what came next? Check your notes. It's there. My notes aren't on your phone, are they? You thought they were for a second? You got confused? I think my notes are on my phone. I have the note-taking app, the physics note-taking app, from the app store. Is it in there, Joey? Is it in there? Well, that is what came next. From that, we have this business that involved momentum. What was our symbol for momentum? P.  How do we define momentum? That's called velocity. Now, since mass is always a positive number, that means that momentum and velocity as vectors, what can we say about them? Those two vectors, they're different vectors. They're very different, not very different vectors, but they are different vectors. But since mass is always positive, and for most of everything we do, it's just a constant, what can we say then about these two vectors? Something about the quality of those two vectors. They're always the same direction, not only the same angle, but actually pointing in the same direction. They just differ by a simple constant. So if we know the momentum, we'll know something about the velocity. If we know the velocity, we'll know something about the momentum either way. But then on Wednesday, I put those two things together for the analysis of a system of particles with no external forces on the system. What then became our working equation? Our working... No? No, on Wednesday. We looked at kinetic energy, but I just asked you to calculate it so we could see what happened to it. It had to do with momentum. For a system with no external forces, which is why it's nice to call this as a system because it made the forces internal, and we didn't have to worry about them then, which is great because we didn't know what they were, and they're very hard to come up with, so we had some pretty good instrumentation to do that. If we have a system with no external forces, then what happens to the momentum of that system? It's the same before as it is after. Then a couple of different ways we can say it, but system momentum doesn't change, or we can say that system momentum before equals the system momentum after. Either one of those is the same, but that was pretty useful, especially in things like car crashes and the like, which we'll spend a lot more time looking at in the next chapter. When things... Two cars crash, it's pretty easy. There'll at least a little something about the crash, and from that we can get out a lot of the rest of the information, which is exactly what they do in accident analysis. The police on site do just that type of thing, and some engineers are making a good living being court experts where they'll take all those pictures and measurements that the police took, and they'll reconstruct the accident using the basic physics of what goes on. So there's an alternate career for you, possibly. Do you have a security guard? Yeah, I don't think somebody halfway through physics one wants to go in and claim they're a court expert and then face the defense on cross contaminants. So, all right. So that's what we were working on Wednesday. So we're going to extend it a little bit here. We'll use our continued example of two cars. Though it need not be. In fact, we can have a system made up not of separate items, like two separate cars, but it could be a system made up of several things joined together.  What would be nice is if we could extend this idea of these two things grouped together as a system, especially a system where there are no external forces, because then we know that the momentum is concerned no matter what happens to those two cars, whether they crash or not, whether they are changing speed or not. None of that matters as long as there's no external forces that we need to worry about. We can figure out a whole bunch more of what's going on. So what would help is if we could come up with some way to represent more of this system than just the fact that we've got some parts in it and we kind of add those things together. If we can come up with some other way to represent the system, well, the things we need to consider. We need to know where this system is Well, how do we talk about a system being some place when it's made up of two or maybe more cars and they're all moving around with each other, all kinds of things could be going on? Wouldn't it be nice if we could talk about the system being some place and not individually break out each of the little parts? Imagine the space station made up of millions of components all put together. Yet there's one place, one spot that represents the position of that space station so that they know where it is and they know what orbit to put it in.  It'd be nice if we could just say this one spot represents where the space station is and then all the other parts do whatever it is they do but we still know where it is and what it's doing. Once we know its position, of course, then we'll also know something about its velocity and acceleration. So it'd be real nice if we could come up with this position that represents the position of the system then, well, we could take the time derivative of that. We know the velocity of the system. Not the velocity maybe of every single little piece but the velocity of the system. Like they know the speed at which the space station is moving but they're not constantly calculating where each little arm is, whether or not one of the astronauts did that thing when they spit M&Ms at each other or globs of juice and all the other tricks they do that use up taxpayer money. If we could do that, that'd be nice. Nobody's volunteering? We can do it. It's really rather straightforward. What we'll do is to establish the position, we'll do what we've always done with position before. What was the first thing we did when we were worried about the position of something? Not, what do you mean, find the origin? Yeah, we establish an origin and it doesn't matter where it is just as long as we all know about it, it's very useful then. So we'll establish an origin. So let's say right there, that'll be my origin. It could be anywhere, it doesn't matter because everything we do from here on is going to end up in the same result that doesn't depend on where that origin is. So here's what we're going to do. Let's see, we've got these two objects each of some mass, just to simply make them m1 and m2. And with respect to our origin, each one of those objects is at some certain place. I'll just simply call x1 and the other one's at some point x2. What I want to do is replace those individual x's with some x that represents the position as a whole because then if I have no external forces I don't care about the individual parts, I just need to look and see where the system is and I can tell a lot more what's going on. So there's got to be some spot, I don't know where, that we can put the entire system. So maybe I'll call that x system and instead of imagining the individual pieces are where they are, which could be quite confusing if there's a lot of them, I'm going to imagine the entire mass at this one spot if I can just figure out where that is. That way I could take out the two individuals, replace them with one system spot and I cut my work in half. Even more if there were more parts. So let's see, let's look at it like this. This is a mass out at some distance. So that's kind of like a mass sticking out in an arm somewhere. This is a mass on a bigger arm sticking out somewhere farther. And I want somewhere where I can imagine the total mass of the system is and where would that be that has about the same kind of balance to it? Mathematically, what I'm trying to do is something like this. If I can take each mass and where it is, I don't know why it starts with two, let me put one in there. If I can take each mass and where it is, not V. See I'm worried so much about what that girl's name is that I came right at the board. I'm so concerned. So I've got each mass and where it is represented like that. And I want to replace that with all of the mass at one spot. It represents the whole system. It's as if we went back so far, stepped back so far away that we no longer see the individual spots. We just see the two kind of come together as a dot, sort of like when we do look at the space station. We see it as just a little dot. We don't see it as a bunch of solar collectors sticking here and there and a bunch of armed laboratories built on the Japanese laboratory, the Italian laboratory, the American laboratory, all of that. We just see it as one little spot. That's what we want to do. Step back so far, and we want to know where that one thing is so we can figure out what that one thing's doing. Well, we've got the answer right there. The thing I'm trying to figure out is where do I place this total mass that represents the whole system so I can just divide through by that. Total mass, that cancels. Well, what is the total mass? It's just m1 plus m2, isn't it? Now I know where to place that center of mass that represents the entire system. In fact, you've heard that word before, the center of mass, where you use one spot to represent a much larger, much more complex object. We now can put it at some spot such that the simple calculation works out. Notice, too, that once we know where that is, we don't care about the origin anymore. Yeah, we measured it from the origin, but then once we've done that, that system spot represents those two masses and it doesn't care where the origin is. From then on, it's exactly the same relation between the two things that we would have had there. So let me just rewrite this here on the board. So we've got this. In fact, let's label it cm for center of mass. You're pretty familiar with that term before. Maybe you don't know how to calculate it, but it's not a foreign term to you. So for a two mass system, it's as simple as that to figure out where that is. So we'll do several examples here in a second. And if there's more than two, big deal. You just add them on. Just keep going. Just add them all on. No big deal. All right, let's see. You now know where the system is. We have a single spot that represents where the system is. Now we want to know how fast that system might be moving. What did we do weeks and weeks, not months ago, when we first had position and we wanted to know how fast that object was moving once we knew its position? What? Xm prime. Xm prime. Oh, take the derivative? Oh, yeah. We don't use prime in engineering physics. Because then it looks like an exponent. It looks like cm to the 1.  We want to know now the velocity of it. So we take the time derivative of it. And I'm not editing that out. Well, let's see. The bottom part, that's just a constant. So that's not going to be a derivative at all. The top part, the constant, what's the time derivative of x1? What's dx d1? Sorry. dx dt. dx1 dt. What? It's the velocity of object one. What is ddt of m2x2? Mind you, we've all taken calculus. That's about as easy as they get. What's ddt of m2x2? m2v2. Plus m2v2. Wait a second. I'm going to rewrite this a little bit. Just a little bit of algebra here. I'm going to move that top part over here. I just moved it over there all by itself. Then I've got this bottom part here. m1 plus m2 times now vcm. Does that look familiar? It looks exactly like the momentum equation we had for collision on Wednesday. However, I didn't say anything about a collision or anything. But we can look at it like this. This is the total momentum individuals. If you want total momentum before, this is the total momentum after. After we combined everything as a system. That momentum wouldn't change because there were no external forces on it. Why should that momentum change? All we did was make a simple representation of the two objects as a single one object. Irrespective of what the two were doing inside the system. I don't care if they're colliding. I don't care if they're passing. I don't care if they're driving up at McDonald's. Well, I do care about that because it's not healthy. But it's not my business. That's even further encouragement. I would hope that what we've done here by determining the position of the system since it now looks exactly like it did from last Wednesday that what we did is correct and useful. Anybody want to take a wild guess of what the acceleration of the system will be? Of the equation we just had. And that even has to do with whether the two are making each other accelerate when they hit. Because a force will cause each one of them to have some MA. But if it's a force between the two of them, it's internal to the system, and we don't care about it. So that's pretty useful to us.  We just throw them all together. And heck, we're laughing at it. We're just having just no trouble. And in fact, we could even put external forces on them because when I had that system there, anything I just did for determining the center of mass of the system doesn't really matter if there's a force on it or not. It would still apply. So we're going to do that more in the next chapter, I think. Well, let's see. Let's go ahead. We'll put on external forces now to have the system. Oh, sorry. I was using Cm now instead of cis. So let's continue with that designation. I only have to know the acceleration of one spot. This M here is these two M's put together and brought over. So this is just going to be M1A1 plus M2. That's nothing more than the application of that last little piece to it. Well, that's the sum of the forces on Object 1 plus this Object 2. I'm going to take one step and then we're going to come back to that to finish things. I'm just going to take one step just to see in general what the sum of the forces on something is. And this could even be force on one from two. It may not be because when we add them all together anyway those two pairs would cancel each other. But just to be completed, it's every force on one, every force on two. But let's see, what do we got here? MMA, which is DVT. I'm just trying to do some of those sum of the forces. See if I can come up with something else here on this type of thing. Well, you know that if there's a constant in a derivative that comes out, I'm going to do the reverse. I'm going to take this constant back into the derivative because that gives us that pair again, MV, which we also know as momentum. So this is DP, DVT, or if you like, you can write it as p dot. Either one's fine if you want to stop at the DP, DVT, no trouble. That's sum of the forces acting on an object. The sum of those forces is equal to the time rate of change of the momentum. The rate at which the momentum changes. SDT, nowhere. So let's take what we just came up with here and put it here. This is the sum of all the forces on the system. So that's going to be the time rate of change of the momentum of the system, the center of mass, if you will. So let's do that since that is the designation we've been using now. Same thing we had, right? And that must be equal to the time rate of change of the momentum of Object 1, DP1, DVT, plus the time rate of change of the momentum of Object 2, DPVT2, and so on. If there's more and more objects, we just add them all up. These things are happening at the same time, then we don't even need the time designation and we're just back to the change in momentum of the system is equal to the change in momentum of all the individual pieces, even if the forces don't sum to zero. We can just add up all the momentums even for those situations where the forces don't sum to zero. We looked at the case when they do come equal to zero, the momentum doesn't change. Even if the forces don't sum to zero, we can still look at our individual particles as a full system. So that takes a lot of the burden off. We don't have to babysit each little piece. We just have to know where the system is and what's happening to the system then the individual pieces will follow that as they will. So we need a little practice then, finding out where this center of mass is so that we can then figure out what's happening to the system, what that represented. So let's look first at a system you're all familiar with, the Earth-Sun system. Oh, sorry. The data I have is for the Moon. So Earth-Moon system, I think for homework, you have to do the Earth and the Sun. So we'll do the Earth and the Moon that way you have no excuse for not getting at least one of the problems right in the homework. So here's the deal. There's the Earth. We call it the Blue Marble. South America, Florida, where Santa lives. There we go. There's the Earth. It probably looks like a photograph from space, doesn't it? It's about the picture of the Moon rising or the Sun rising over the Moon. They took from the Moon when they were up there. That's what that looks like. Somewhere nearby. Too bad I didn't bring my green chalk because everybody knows the Moon's made out of green cheese. There's the Moon. Some distance away. We're going to find out where the center of that system is. The center of mass of that system because as the Earth orbits around the Sun, it's the center of mass that orbits that follows the orbital path, not the center of the Earth that does. As the Earth goes along its orbital path around the Sun, it's the center of mass that follows on that orbital path. So the Earth actually wobbles a little bit as it goes around the Earth, and then the Moon does even more than that as it circles around that Earth. As the two of them together follow the orbit of the Earth around the Sun. So I want to find out where that center of mass is. That's what's orbiting around the Earth, that center of mass. We can do it just like we did with the other picture with the two cars there. We can pick an arbitrary origin. Any suggestions? As good as any. No reason it can't be actually fixed to something we already know. What's nice about that is we know certainly how far away the Moon is from the Earth, and we're going to need that distance. So the location, the location of the center of the Earth measured from our arbitrarily chosen origin will be... How are we going to find that? Remember? Just had it up a couple of minutes ago. It's gone now, but what was it? The mass of the Earth times the location of the Earth with respect to our arbitrary system plus the mass of the Moon with its location with respect to the arbitrary system divided by the total mass of the system. Notice, once we come up with this location of the center of the mass and it puts it wherever it is, we don't need the origin anymore because that point is fixed. It's just that now we know what it is. We know where it is. We can measure it from there, or from there, or from any other place we want. We know where that origin is, so it's not artificial that we're putting in this arbitrary origin. It's going to allow us to find a spot and then once we know where the spot is, we don't need the origin. We know where the spot is from that on. What is the mass of the Earth? Nobody knows offhand? Mike, is that on your awesome cell phone app? No, you didn't get that app? Darn it. So you put your physics notes on there but you can't get anything off the mouse. Len, what are you doing? Looking in the book. Good job, that's where it is. It's in there somewhere. Yeah, it scared you, didn't it? It's a sweat. So, Len, what's the mass of the Earth? 5.98 times 10 to the 24 kilograms. What's Xe? The location of the Earth with respect to our arbitrary origin. It's zero. See how convenient it was to put the origin there? It's zero. So we didn't even need the mass. Well, we do need the mass of the Earth because we need it down here. That happens to be zero. So choose your origin carefully and you can sometimes make things easier. So that's that mass times zero. What's the mass of the moon? 10 to the 26th? 22nd. 22nd. Can I say I don't think it's heavier than the Earth? And what's the Xm of the Earth? What should we use? Sorry? No, I mean, what are we going to get and Len to look up for us? Is that the radius of the moon? This Xm, this represents the location of the moon with respect to our arbitrarily chosen origin. What we call the orbital radius. It's not a perfect circle. It's a little bit ellipsoidal, but we'll use the average and that's what should be in the book there. They have the radius of the orbit of the moon, Len. Yeah. Divided by these two masses, add it together. 5, 9, 8 times 10 to the 24th. Plus, that's zero. So we put the origin right at the... Oh, by the way, even saying that, was using this whole idea of locating a big object with a single little point. So we're doing... You're used to doing that anyway. Nobody even flinched. Len was flinching at other stuff. Worked that out, of course. You got to figure it's going to be somewhere like what I drew. It's going to be a lot closer to the much heavier Earth, the much more massive Earth, much closer to the much more massive Earth in our little system as M gets bigger, X gets smaller, so they all balance. In fact, that's pretty much what we're doing, and you're just balancing the masses so that they balance at the same spot. What do we got? Bill, you got something? Yeah. Not going to share it? Do we have to buy it from you, take up a collection? Maybe. We'll wait. We'll see if we can get it for somebody for free. Maybe we can get it from somebody with a little more generous heart to come ask them if they're in favor of the term. Seven. Seven what? Is the answer? Seven what? Got it? What is it? 4.7 times 10 to the sixth meters. So, pretty close, pretty close to the Earth. In terms of the other distances we're talking about, 10 to the eighth, all the way out to the moon, this is about a hundredth of that. So, it's one-one-hundredth of the distance from the Earth to the moon. Len, can we trouble you for one other thing? What's the radius of the Earth itself? 0.4 times 10 to the sixth meters. Notice that then. The center of mass of the Earth is actually where? Inside the Earth. No reason it can't be. That's the spot that orbits the sun in a smooth orbit. Other than that, the moon and the Earth both wobble around that spot as they do their orbital motion in orbit around the sun. It's that spot that's doing the orbit. But that's nice. Now we know where that is. We don't have to calculate the Earth and the moon separately. If we want to know the momentum of the Earth and the moon system or the acceleration of the Earth and the moon system, we can calculate all that based on that one little point. Your turn. Here's a molecule made up of a couple atoms. It'll make it very simple for us. It's not a chemistry class. We'll say all these atoms are the same size. It'll make things real easy for us. Our first time through this. Five atom molecules made up of five identical atoms. C5. This distance. 0.1 nanometers. What's a nanometer? 10 to the negative ninth. So this is 0.1 times 10 to the negative ninth meters. It doesn't matter. We'll keep it all in nanometers and not mess with the 10 to the ninth tables. This distance. 141 nanometers. This also 141. This angle here. 130 degrees. Once you figure out where the center of mass is. If we built this and we could do it out of spaghetti and marshmallows. Where's the spot where this whole system would balance? That's where the center of mass is. Just eyeballing it. You've got to figure somewhere in there, wouldn't you think? So that's good. Because when you come up with an answer, if it's wildly off of that spot, you've got to figure you did something wrong. Alright, what's our first step? Let's do this together and then you can do the rest on your own. What's our first step? We'll use that atom right there as the origin. Where the center of mass is. If you don't want to calculate it or find the one person in class you're in speaking terms with. All five atoms are the same atom. We're extremely close. We didn't draw that it's tilted on this axis. But with respect to the moon, I don't know. Oh yeah, it is tilted on this axis. That's the earth? Perpendicular? Or in the plane? That's the sun. It's fiery and yellow. And that's the orbit of the earth. And there's the moon orbit in that same plane. Or does it orbit? The orbit's around this point. It does? I don't remember. I just know that sometimes it's there in the sky and sometimes it's not. I just don't have to remember the specifics of that. Alright, let's see. We're looking for the position of this center of mass. Once we know where it is, then it's fixed to the molecule and we don't have to worry about where the origin is anymore. Because then we know where it is. Just add up all the little pieces. Just do exactly that with it. I always ask somebody sitting beside you before you ask me, I charge a lot more.  Don't forget, this is a two-dimensional molecule. So we also need to know where YCM is as well as XCM. It's just got a lot harder, isn't it? Now you're sweating. And the stakes just went up now. Just like that, with the stroke of shock. It's doubled the amount of work you have to do. YCM and let him do XCM. Right, Tyler? Which one would you volunteer to do? YCM. YCM as well. YCM. Since it's symmetric about the X-axis, then YCM is zero. It's right on the X-axis. We know that. In fact, I ought to drew that. So always look for some kind of symmetry when you're locating the center of mass. Because by definition, the center of mass is going to be right on the axis of symmetry. In this case, the X-axis is the symmetry axis. All right, so let's, we'll number these one, two, three, four, and five. Now we have to do that for five of them. M1X1. M2X2. X3. What did I say about the mass? Mass are all the same. So in fact, the mass, oh, now it will have mass distributed out of each of the pieces. It will also cancel the X's and divide by five. Actually, it's kind of like the average distance then. Well, even that makes sense. We just got to make sure we're using the right X's for each of this. What's X1? We have to account for the fact it's to the less of the origin. That's the only way we do that. So negative 0.1. X2 is zero. They're all the nanometers, so I'll put that down at the end. X3 is 0.141. What's X4? The origin. So it's 0.141. That little bit of distance there, whatever that is. So that's the 141 times the cosine of 65 if you want. Does anybody have that number?  What? 0.2005. Is that confirmed? 005, I'll just call it 201. Is that correct? That's four. What about five? Same distance. So I'll just multiply that by two. That's over five. And we figure it better lies somewhere in here, probably a little bit closer to three than it is to two. What's that come out to be? Four or something like that? Somewhere in there. Which is just to write just about where we'd expect it to be. Anybody not get that? 0.88. Okay. Oh, that's what Joey was trying to say. All right, Joe. There you go. Now, no matter what else that molecule does, we know where the center of mass is going. If we put some force on this molecule, all we have to do is worry about where the center of mass is going. We don't have to worry about each of the individual pieces separately. It could be that in some situation, you actually need to, but we're still working pretty in general. Anybody not get that for a reason? It'll give you the world's hardest problem. I'm going to come back in the morning because you'll still be here. There's a Q. L on the side. Center of the Q, because it's symmetric on... The center of mass is automatically at the... on an axis of symmetry and it's got axis of symmetry in all directions. So, this one has a little bit of a trouble though. Not a trouble. It's got a whole drill through it. Something like that. Now it's no longer symmetric in all three directions. Just to help with the sketch, I'll call that the x-axis. That's the z-axis. That's the y-axis. So, looking at it in the x-z direction, which is looking right down this hole there, you see this. There's the hole. To locate the center of axis, sorry, the center of mass, we're going to need xcm, ycm, and zcm. Three-dimensional solid. To locate a single point, we're going to need three coordinates. Anybody want to volunteer for any one of those first? It's centered in the z direction. This is the y one. What's the y dimension? If I put the origin down here at the corner, just give me a quarter of a distance. It's got two planes of symmetry, which is going to put the center of mass for whichever two, right at the center. For example, if we look at this, in the z-y plane, that's y, that's z, there's the hole. If we look at that from the y-z plane, so where's the center of mass, at least in terms of both y and z, it's right in the center. But you have each, just have like x, y, z, so you have to have each one. Oh, how do you write it down? I don't care. That's just no taking. We don't have xcm right now, so... because we need to find out what the center of mass is. This is a hole, so there's more mass of this stuff to the right than there is to the left, so the center of mass for a quarter. You've got to figure there's going to be something like that. So how do we figure out how big xcm is? The other two, just by symmetry, they're right where they were, they're right in the center. How are we going to find it? Well, we do it just like we did it before. x1m1 plus x2m2, where what does the 1 and the 2 stand for? Not even halves. You can make it even simpler than that. Because if we made it a half here and a half here, we've got to figure out what the mass of this part is minus the cylinder drill down. That's starting to get a little bit messy. Minus the... That's probably the easiest way to do it. The mass of the cube minus the mass of the cylinder. Because that's pretty easy. Anything that's missing, we'll just give a negative mass because it's taken out of the system, so we'll take its influence out of the system. What's the mass of a volume, though? The cube's not a whole. I said, what's the mass of a volume? What's the mass of any volume? Let's see. Rho equals mass over volume. Know what that means? That's density. So, however... whatever volume they have, times the density equals the mass. So, let's see. Let's let 1 equal the cube and 2 equal the whole. Where's the center of mass, x1 of the cube, without the whole missing? Because we're going to take off the whole second. x1 is L over 2. Its mass is its density times its volume. What's the density of a cube? I mean, the volume of a cube. L cubed. So, there's x1 and 1 for the cube as a whole before we drilled out the whole. It's x2. Sorry, what is x2? The center of mass of the whole. You're right there. It's one radius from our edge L over 2. Sorry, no, L over 4. What's the mass of the whole? Density times the volume of the cylinder. It's a whole, so we're going to subtract. We're taking the whole out. We're going to take out its influence. Density times the volume of the cylinder. Density of... sorry, the volume of any cylinder, some h, of the base times the height. So, it's pi r squared h. It's the radius of the whole. So, there's pi r squared. What's h? The height of that whole. It's 2n2. Minus because it's a whole. It's something we took out. And then the mass... Well, the mass is these pieces we have here. Again, we just put them back there without the x part. What is this material Huh? Is it aluminum? It doesn't matter. It's canceled out. Any object of one single material that looks like this is going to have the exact same center of mass no matter what it's made out of. About that, and you may work it all the way out. We know it's going to be a little bit over halfway. So, it should be a little bit bigger than L over 2 0.56L. A little bit over halfway. Now, if that was some part of the space station we needed to move it, we know how to move it now because we know where the center of mass is. If that was some object that was going to float, we know how it would float now because we know where the center of mass is. All we had to do was use the negative for any part of it that's missing. Alright, see you tomorrow. Be ready to work on your reports.


emotional growing pains that we go through in life. Nothing about which feels normal but unlike physical growing pains, no one reassures us that it's normal. The sense of guilt that we feel because we set a boundary with someone and the pain that creates in our emotions and our relational situations. The loneliness we feel sometimes because we stepped away from a toxic relationship. The anxiety we feel because we stopped trying to reach for perfection in our lives and we've got a reality check sometimes. The fear we have after expressing an opinion to someone who normally would have been quiet around because we dominated by their energy. We found our no voice. I don't agree with that voice. And all of it brings emotional, relational growing pains and it's okay. I've gone through a lot of this in the last sort of decade plus and couldn't find anyone to say to me it's okay because if anything people tried to fix me like there was something wrong but there's nothing wrong with you if you're going through that today in this season of your life. You're having emotional growing pains. It's all good as you change, reinvent, morph and shift into the next version of yourself.


I realized life is finite, and on July 16th, 2004, I decided I was going to build a brain-inspired computer. I'm an IBM Fellow, IBM Chief Scientist for Brain-Inspired Computing. The human brain has 100 trillion synapses packed into a cavity the size of a two-liter soda bottle, consuming the power of a 20-watt dim light bulb. And yet it is capable of tasks that make today's computers look like merely calculators. The true-note chip with 1 million neurons and 256 million synapses is essentially a supercomputer the size of a post-it stamp in the power of a hearing aid battery. So if you think of today's computers as fast, sequential, symbolic left brain, then you can think of true-north as pattern recognition, synthesizing, slow, sensor-actuator right brain. Brain-inspired computing will augment today's computers so that instead of us adapting to the computers, computers will adapt to us, our homes, our transportation, our work, and to our society. Imagine powerful supercomputers that can help safeguard our cities and planet so that we can make the world work better.