Scaling Blockchains – Computerphile


I’m going to talk about the issue of Scalability in Bitcoin but before that I will Provide Some Background on Bitcoins and Then We’ll Slowly Build it Up to the point where We can See the Issues in Bitcoin Scalability and what Is? Being Done in Current Blockchain Designs to Address These issues in Scalability the key Metrics that, we are Looking at Here Are the Throughput of the System that Is what Is the Maximum rate at Which Transactions can be Handled By the System in Terms of writing Them to the Blockchain and then The other Metric Is that of Latency That Is from the point When A client Submits a transaction to the system? How Long Does it Take until it’s written to the Blockchain I Think some History, Would be nice so bitcoin Appeared on the Scene in 2008 On an online Meaning Mailing List by a pseudonymous Author Called Satoshi Nakamoto Whose Origin Is Unknown and Then The next Year in 2009 There was A software Release of Bitcoin and it Generated A lot of Interest Since its Inception because it went on to become one of the biggest Digital Currencies of our Times so just Today a one Bitcoin is Worth About $6,000 yet on the other end of the Spectrum There are People who have Said that Blockchain is the biggest Bubble of our Times the Aspect of Bitcoin that Really Gives it its wings Is The Blockchain Which Is at the heart of Bitcoin Now A lot of People Have Started to become Interested in Block Chains Because These can be Applied to other Scenarios Which Are Beyond its immediate Application to Digital Currencies We did A video with tom Scott About online Voting and The Blockchain was not mentioned at all but Lots of the Comments of People who Watch that Video Say? Why can’t We do voting with a blockchain Is this one of the Applications you’re Talking About yes Exactly if You look at the Blockchain One of the key Properties of the Blockchain that Distinguishes It from Regular Traditional Databases Is that of public Verifiability and Public Verifiability is enabled by two other Properties Called Integrity and Transparency Now by, transparency, We mean That anyone can verify How the State of Data has Been Updated and By Integrity we mean that anybody can Be sure that the Data that they are Retrieving Is Not Corrupt and it is correct. I can imagine that it would be a feats an Engineer A system for 60 Million People Living in the Uk but Never mind how, Many People are Living in China or India Or some of the other Nations That have got, Many, Many more People. Is that the sort of Scalability, we’re Going to be Talking About Well This is the Kind of Scalability that, We are Going to Talk about but Let’s not Forget that Systems like Google or Facebook Also deal With may, be much greater Magnitude of Users but the advantage that These systems have, over Systems Like Blockchain Is that They are Centralized Systems that are under The Control of a single entity Or a consortium of Entities While in A blockchain the Network Is Between A Fully Decentralized Set of Nodes so what does a blockchain really Look like Well you Can Think of a blockchain as a linked List of Hash Pointers so a hash Pointer Is Simply A Hash of some Data and Now We are going to look at a linked List of Hash Pointers so in the Beginning We need to start from Somewhere so we have? Sort of A Dummy Or a Padding, Data Called Genesis Block and We Take the hash of This first Block? Which Is Included in The Header of the next Piece of Data So there is A hash Pointer Which points to the Previous Piece of Data and new Data then the next Block and it’s Called ST-1 Then Imagine that you Have Another Piece of Data and this is the simplest Form of Lock Chain so as you can See This is a linked List of Hash Pointers Now the hash Point Ourselves Two Purposes The First Purpose Is that it Uniquely identifies The Previous Block of Data so a hash Pointers IDentifies The Data and the Hash Pointers due To the Properties of Hashing Functions Also Confirms that the Data has not, Been Corrupted you Can Think of it as a temporal evident Log and Anybody Can independently Take Hash of this Data Match it with the hash included in The next Piece of Data Compare These Two and if These Two Match then They can, be sure that the Data has not Been Corrupted There Are Two Kinds of Operations That Can be Performed on a blockchain One is a read Operation and one is A write Operation Now as you might have guessed Read Operations are Easy Because they, Simply, Involves Retrieving, some Data of the Blockchain However Write Operations Are More Challenging Because They Can Potentially Hurt The Properties of Transparency and intake Integrity That We Expect From the Blockchain So a blockchain has Two basic functional Components one Is to Validate Transactions and the other is to write to the Blockchain We are First going to Talk about Validation of Transactions what is the Transaction? You Can Think of a transaction IS an Operation that Changes The State of Data That Lives on the Blockchain Okay, so let’s Look at A very Simple Example in The Context of Bitcoin So a transaction might Look something like Say Ten Bitcoins to Bob and This Transaction has Been Generated by Alice now alice has Two things to Prove to the Blockchain Network Alice first has to prove that She Owns These ten Bitcoins so she is able to Pay them to Bob which means that as input She, also has to Provide the Id of the Block in Which alice Became the Owner of These ten Bitcoins Say it was Zero Zero seven And the other Thing that alice has to prove Is that it’s actually Alice who is generating this Transaction and not Somebody Else who is pretending to be to be Alice for This Purpose She Takes Advantage of A cryptographic primitive Called Digital Signature so She Basically signs this whole thing With her private key She then Submits This Transaction To the Network Any Node That receives This Transaction if it wants to Validate This Transaction it has to perform two Checks First to Check That alice Actually Received Ten Bitcoins at some Point in The History of the Blockchain So if You Remember the Structure of the Blockchain, was something like This and There Is this Head of This Blockchain? so it will Traverse the Blockchain and At some Point it will reach the Block Where Ellis Came Into the Ownership of These ten Bitcoins say it was this One? so the first Check has Been Passed the other Check that it has to do Is to Traverse Back in The Blockchain and Confirm That Alice Actually possesses These ten Bitcoins and That Up until now alice has not Tried to Pay These ten Bitcoins to Anybody Else Because then that Would be Considered a double Spend Because Imagine if Alice has Already Paid out These ten Bitcoins to Charlie Then She’s not the current, owner of These ten Bitcoins even Though she, was at. Some Point in the Past So that’s Another Thing that the Node has to confirm that from the point when These ten Bitcoins Came Into The Ownership of Alice She did not at Any Point Transfer Them to Anybody Else if The Transaction passes Both These checks then the next Step is to write it to the Blockchain now this Would be Straightforward in A centralized System Where There are all trusted Nodes and They’ll Just Simply perform the right Operation? However This is Significantly more Complex in A fully, Decentralized Network like that in The Blockchain Because all the untrusted or semi Trusted Nodes Have to reach an Agreement Among Themselves Whether They Are going to write this Piece of Data or transaction to the Blockchain or not This is where The Issue of Consensus Comes Into Picture Consensus Simply Means to reach Agreement About A value Among Multiple Nodes Within a network Now in The case of Bitcoin this Consensus is done By getting all the nodes To solve A hash Puzzle or Provide some Proof of Work This is also called Mining and for this Reason Potential Bitcoin leaders are also Called Miners a Miner can, also be thought a successful miner Can, also be Thought of as a leader Because when the miner has successfully solved the puzzle? It can write to the Blockchain then there are two main issues in Bitcoin? However Note That Even Though I mentioned These issues in The Context of Bitcoin These are Shared by all Blockchain Systems That Work, Along the Same Principles as Bitcoin The first issue Is that of Folks now Bitcoin is Decentralized System and it’s a peer-To-Peer Network Where Different Nodes communicate Transactions and other Information to each other using a gossip Protocol Now the Network has its Own Limitations for example Propagation Delays or the transactions Could Simply get lost on its way Or a node could be simply bad This Could Mean That The Nodes in The Network Could Potentially Have Different views of the System what might happen Is That A minor Builds on Top of this Block While Another Minor who has not yet Heard About this Block Builds on Top of some other Block the Blockchain has Effectively Been Forked and Some Nodes will Continue To extend This Part of the Blockchain While Others Would Continue To mine on Top or extend This part of the Blockchain This is Really Bad for the Blockchain and it Defies the Fundamental Philosophy of The Blockchain Which Wants to Provide A consistent view of the World to its Users So all systems need to have some Mechanism to resolve Such Conflicts in the case of Bitcoin There Is This Implicit rule that Nodes Who find themselves in A Fork Situation Should Follow the longest Fork you mentioned before what I heard as A Gossip Protocol Is that yes What’s a gossip Protocol a gossip Protocol Is most naive Kind of Protocol where for example if There are Five People in the Room and They want to communicate some Information to each other Then I’ll Tell that Information to as Many People I know in the Room and All These People will Also communicate The Same Information to everybody Else in The Room so everybody is talking to everybody Else the other Issue in Bitcoin Is that of Performance Now There are two key Metrics That Are used to assess the performance of such Systems, one Is that of Throughput and yes the other Is that of Latency By Throughput, We mean that what Is the Maximum rate at which the System Can write Transactions to the Blockchain and by latency we mean that after the point at which a node hears about a new transaction How Long Does it Take to actually write it to the Blockchain Now in Bitcoin the Throughput of the System is Basically a Function of Two Properties of the System – Block Size and the other Is the inter Block Interval What is a block We’ve Been Talking about Transactions so far A block Is simply an Extension of that Idea? You Package a number of Transactions Into a block So what Gets written to the Blockchain Is not a single Transaction but Rather a block of Transactions The Size of This Block in Bitcoin is Currently Capped at one Megabytes the Inter Block Interval Sort of Relates To a Difficulty of the Hashing Puzzle Because that has to do With how fast Miners Can solve the Puzzle Currently This Is set at about 10 Minutes and The idea Is that the Inter Plock Interval Should Be large enough that Majority of The Nodes in The Network Have Heard About a new Block That has Been Added to the Blockchain Before Another Block Is Added To it to avoid Folks with the current Block Size of 1 megabytes and An Inter Block interval of 10 Minutes the Throughput of Bitcoin is at is capped at about 7 Transactions per Second and A client That Submits a, transaction to bitcoin It has Generally on Average to Wait About six More Blocks Are Added to the Blockchain to be Sure that it’s Block is Actually Permanently Added to the Blockchain Now this is very slow Just to give you an Idea Main Stream Payment Processing systems like Visa Can Process Transactions Up to at up to 24,000 Transactions per Second With a latency of Just A few Seconds Now One might Argue that Reaper Amat Rising the Inter Block Interval Value and The Size of the Block Maybe These performance Metrics of Bitcoin Can be Improved It Turns out According to a recent Study that even Then the best We can do IS 27 Transactions per Second and a latency of About 12 Seconds People have now Started to look at Options To Redesign Block Chains to Address These issues of Forking and low Performance Now Or that the issue of Consensus Is not new it has Been Studied for Well Over Two decades in Classical Distributed systems and There are Well Known and well tested protocols that enable? Agreement Among A group of Nodes That Can Tolerate Two Kinds of Errors There are Crash Failures and There are Bees and Time Failures the protocols that Are Well Known for crash Failures are for example raft Paxos and so Forth By crash Failures We mean that A node Simply Becomes silent for example because it Crashed and Is not able to actively Participate in the Consensus Protocol Resent time failures are worse in This case the Nodes might behave arbitrarily or Inconsistently for Example Sometimes it might exhibit The behavior of Crash Nodes By Becoming silent or? Sometimes it might Lie about the value on Which Consensus is Required The Most Popular Protocol for Tolerating Bees and Time Failures Is called Practical Byzantine fault Tolerant Protocol Or Pbft so what do These classical Consensus protocols have got to do With Bitcoin or block Change in General Recall That in Bitcoin the way to reach Consensus, was that A miner? Solves a Puzzle so Basically it receives The Transaction it does Mining mining Mining Solves a Puzzle and then Say This is the Blockchain it Gets to write The Transaction to the Blockchain Now What Researchers are Currently looking at Is What About if We replace this leader with a group of leaders so instead of Having one Leader who is a miner We have a group of leaders? We’re Not Really Mining I mean the criteria for entering this Group, of leaders might be Mining but Once They enter This Committee or Group They Are not Really Mining so what this Group Does Is that when it receives A transaction it Basically runs A Pbft protocol Among The Nodes and Then They Reach an Agreement Whether or not They are going to write this Transaction to the Blockchain so if They Decide to write you to the Blockchains Then it’s A collective Decision of all the Nodes in This Group and it is Unlikely for A majority of These Nodes to be Corrupt and do Wrong things with the Blockchain Instead of if There Is One leader who Is in Charge of this task how Is that collective Formed you mentioned that mining might be A criteria for entry but how Would you how Would you put Those Groups Together I mean how Would We not Know There’s some massive Conspiracy go here Honor Suppose? This is Actually A very Good Question and This Is one of the Research challenges in This Area right Now Because in Classical Systems The Entity That Controls the Network Already Knows the Nodes so this Is not an issue in the first Place But With Decentralized Networks Identity is A Huge issue who, do you, allow to join These Elite Group of leaders One Way that I mentioned was to sort of Create A cost for entering the Group by getting nodes to do Work Whether By mining but more Recently this Can Also be a Proof of Stake Proof of Space or Anything Else but This Really Is an Open Research Challenge and The The Trade-Off Here Really is that We want the Nodes Who want to enter the Committee to show some sort of Commitment that They’re not Going to Misbehave Either by Making Sure That They Have used Their resources for example by mining Or they have sufficient Stakes in the System that they Wouldn’t want to Misbehave for Their Own Benefit so that’s a good way of Preventing or maybe Limiting The Amount of Folks That happen so does it Make it any Faster It does to a Certain extent Because we no longer have to worry about an interlocked interval to make sure that folks do not happen because once the committee has Reached a decision that we are going to write this block to the Blockchain Then that’s it it Would Be written to the Blockchain for Sure However There is a limit to how much performance gains We Can achieve to the system Because this Committee Is Still the Bottleneck Really Every Node is Handling every Single Transaction So it doesn’t Really Scale in A scalable Systems when you add more Nodes to the Network it Should Ideally Improve the Throughput of the System However The Problem With These Single Committee Systems Is That because of the way Pbft Works The Because of Messaging Complexity and The Amount of Complexity Involved in Reaching an Agreement The more Nodes You, Add to this Network The Transaction Throughput Actually Slows Down This is an issue and it Is an open research area right now a classical way to improve The Scalability of A system at least in The Context of traditional Databases Is that of Sharding by Sharding We mean that you split the State or the? Data Among Multiple Committees Or Groups Within the Network so Basically Instead of Having a single Committee You have multiple Committees and Then You Make These Committees Responsible for managing Transactions That have to do with Say, Data from a to F and then Data From G to K from L To P and so on Essentially you have Split the Transactions Among multiple Committees So not every Node is Handling every Single Transaction right now but it brings its Own unique Challenges Because of its Application to A setting for which it wasn’t written in The first Place So for example the idea is also that each one of These Committees Have Their Own Block Chains for example But what if There is a transaction that Takes as an Input one Piece of Data from this Blockchain and One Piece of Data from this other Blockchain so Which Committee is going to Handle This Transaction now Block Chains might not end up something Quite like the Internet However in One Form or the other They are Probably here to stay But There’s Still A long Path between Where We are right now up until the point Where They are as Widespread as Say for example traditional Databases I’m so i mean that’s about Unfortunate is the problem With Cryptography Is that We couldn’t Ever use truly Random Because, we? Wouldn’t be able to decrypt it again We have our message bits Which are you know Naught 1 1 Naught something Different and We xor These together? One bit at a Time and that’s how, We encrypt and the nice Thing Is

100 thoughts on “Scaling Blockchains – Computerphile

  1. Bitcoin's blocksize is no longer capped at 1 MB, with SegWit update activated in Auguest the maximum possible blocksize is 4 MB, but on practice it would be close to 2 MB. We've already seen a 1.3 MB block.

  2. Dr. Bano gave the clearest and most succinct blockchain description and summary talk ever! Does she have other presentations you can recommend?

    Perhaps a sequence of videos? I would very much like to see her start her own YouTube channel, much like her fellow Computerphile alumnus Rob Miles.

  3. I admire that Dr Shehar Bano manages to talk about something substantial without non-functional pauses, hesitations, or saying "uhm".

  4. So why not just form a super-committee out of the committees governing the segments / blockchains for the time it takes to resolve a transaction that needs data from those segments / blockchains? Anyways, that's my 0.0002 satoshi …

  5. Alright she got one thing VERY wrong. She described miners as being leaders in the blockchain when in fact they have little if any say in the consensus of the network, the nodes and their users running the software defines each blockchain and is the only factor that pertains to any question of consensus.

  6. How do you index the blockchain so that you can quickly find all transactions involving Alice? Can this be done without every node having to store the entire blockchain?

  7. Block chain voting? Yeah, like middle America is going to trust a liberal elite computer scientist to tell them the vote is verifiably not corrupt.

  8. Wow stunning woman and very clear explanation of something quite complex. I've never really understood how cryptocurrencies work but this cleared up a lot.

  9. There is some sort of a very high-frequency noise appearing in the sound of the video at about 4:40–4:50. Am I crazy?

  10. Bitcoin didn't used to be a bubble, but now it is because Core and Blockstream have removed usability by keeping the blocks too small, increasing the transfer fees and making confirmation times unpredictable.

    To escape their influence, right before the activation of Core's new useless technical debt called SegWit, Bitcoin Cash was created, continuing the blockchain with unchanged structure but bigger capacity.

  11. Dr. Bano is smart, tells the story really clearly, and I could listen to her accent all day. But I smiled when she’d say we don’t want to get forked. No we do not!

  12. I wonder how the idea of a hierarchy of sharded committees works or not.

    Like, if the committee that handles A-F needs access to G it could pass it on to a higher committee which handles A-N, with the highest committee handling A-Z.

  13. fascinating and clear explanation. Keep going on this topic! would love to hear about the other decentralized consensus methods mentioned midway through.

  14. I would love to hear what she has to say, but I am absolutely horrible with accents – I can't even understand accents in my native language.

    Could we get subtitles on this video? I know my request may be hurtful, but shit, if I could fix my sound processing, I 100% would.

  15. There are now many competing technologies such as blockDAGs, Tangle and Hashgraph. All of which are Directed Acyclic Graphs. Tangle gets faster with scale and is only limited by bandwidth. Hashgraph has Asynchronous Byzantine level security and throughput over 250000 pre-sharding.

  16. So here you discuss possible improvements to the blockchain, but can these changes be implemented on existing blockchains? Or everytime you want to change the blockchain a new genesis block must be created?

  17. This is one of the best explanations I've seen given for Bitcoin for a general audience. For once, it seems quite accurate, compared to what I know of the system.

  18. They’re not, strictly-speaking, blockchains, but I wish she had discussed Directed Acyclic Graphs, which are a type of distributed ledger that do reverse the scalability problem.

  19. From what I remember, blockchain transparency is the issue with voting, as it makes voting traceable, eliminating the secret ballot. Of course, many attempts are being made to eliminate this problem win various ways, but this can add additional problems.

    For example, one proposal I just read can be taken over by only a few people organizing the vote, thus relying on them to be honest.

  20. So basically, Bitcoin is doomed to failed? 1 MB per block is enormous. Where is this all going to be stored? 50 years from now? Or even 100? Plus the forking issues will make this too unreliable at scale.

  21. I don't see why using shards would be too different than purposely allowing the blockchain to fork, then implementing some method to merge those forks back together.

  22. proof of work (mining) is the only way to guarantee censorship resistance. Sorry but Proof of Stake (or whatever else) is just not useful in the context of a open blockchain system.

  23. Great interview! I'd love to see a follow-up video.
    Please elaborate on how the IOTA Tangle fits in the mix. Does it solve the scalability problem? What are the new challenges we will face when using Tangle?

  24. So the concepts are amazing, and blockchains are the first, very naive implementation of said concepts.
    It is essentially nothing but a linked list with a protocol layered on top to ensure tamper-proofness.
    Can't wait for a better implementation! Smart contracts have the potential to be completely transformative to our society!

  25. Why not have a disposable committee? I think the instinct to trust the leaders is the problem. Instead once a result from a leader is used, blacklist that node for as long as possible. If I am being nefarious I have to wait a very long time to come become eligible again, thereby demotivating the the nefarious behavior.

  26. The annotations at the end of the video, which link to the Krack attack and botnets, are missing.

    Great interview btw ^^

  27. STONITH — shoot the other node in the head. This concept just came to my mind, hearing about PBFT and other consensus protocols. Never thought I would associate those with Bitcoin. Cheers!

  28. Just stop. Everything is based on having many seperately owned nodes willing to participate in calculation. Consensus can't be trusted when there are few calculators. No one has come up with a good way, that doesn't unduely pressure the node owners to collude. Cost of entry makes it more elite and a committee itself is collusion. Block chain should be nothing more than an interesting lab experiment. It is useless for real world applications at this time. Sharding makes this worse because you need so many more nodes willing to participate. People need to stop trying to sell this as ready for prime time.

  29. I think blockchainesk technologies will take over the internet in a decade, conservatively 2 decades. The vast majority of internet functionality will take place through distributed blockchain apps using distributed storage and distributed computing. A whole new industry of distributed workforce, a kind of elance/odesk/fivver 2.0, will compile apps.

    The more I process through the events it seems to always lead to this conclusion.

    Ironically, as a minarchist/ancapper, it seems to me we may end up with a non-hierarchical utopia after all. I mean that quite literally. In 20-30 years, we may have trillionaires mining asteroids, but I don't think there will be anyone in the world involuntarily without basic necessities of food, water, shelter, and basic medical care, through the free market. Unless there still exists totalitarian government's artificially preventing it.

  30. pretty much confirmed my suspicion that the #1 problem is scalability. 7 transactions per second is indeed very very slow.

  31. Seem like Blockchain is totally in a bubble right now… Their value is rated soo high, but the reality is that this technology is yet to be able replicate the conventional banking transaction rate, and there's more work to be done…. Of course there's plenty of room to improve, but lets hope Blockchain users are wise enough to spend their 'bubbling' money on R&D of Blockhain infrastructure rather than just sitting on it… the money is like an IPO, you have to quickly utilise it to create a product rather than just letting it 'rot' when investor realise their investment is just hype.

  32. I heard that the Bitcoin Core team don't want to do the hard fork of 2MB block increase and want to implement the lightning network instead. How does the lightning network would actually help scale if it is a system built on top? you would still have 1 MB every 10 minutes. I agree that increasing the block to 2MB is just an immediate solution and not a long term one because in a few years we will be back to the beginning. Can you make a video on this lightning network proposal?

  33. If I pass some bitcoins to you, then why is some leader involved? I need to sign that they are now yours. Then get them added (is it this last bit, to stop people adding random stuff?). With forks, could they use merging? Could be a problem with double spending. Do coins have an ID or is there just a ledger of spends resulting in a balance?

  34. Bank heists will get a new meaning in bitcoin world. In the real world you just scrap and write the paper off. It has no value anymore after that so to speak. This is impossible with the blockchain.

  35. Finally someone actually talks about why blockchain is fundamentally bottlenecked. I have to explain this to everyone all the time. I personally don't hold out much hope for figuring out how to scale such a thing.

  36. Very fine! She seems well prepared and watches her pronounciation very carefully. I understand her by far better than some scotsman talking way too fast 🙂 One of the best videos lately. And actually a lot of content again (for a change ;-/ )

  37. A professor that does more than just talk about the current trends – takes part in them – and has opensource repositories on github!

  38. When it comes to scaling up blockchains, solving some problems requires a change in the architecture. A tangle (or IOTA) might be an option for that. It still provides the basic features of a blockchain, but doesn't requires mining, hence enables micropayments in IoT scenarios.

  39. The subject of the video is fascinating, but can we take a moment to compliment the presenter? She has such a clear way of speaking. No "uhh"s, "well"s and such. I was like she had it written beforehand and was just reading. I was listening to the video while doing the dishes, and it felt almost like an audiobook. Amazing stuff, I'd like to be this good at public speaking one day.

  40. Yeah, let's give these "leaders" such a big stake in the system that they won't want to misbehave.

    That worked so well with banks.

    What could possibly go wrong?

  41. This was a very good and realistic explanation. It's the first video I came across which has described things the way they are.

    I was hearing a lot about blockchain, and all were portraying it like it's the perfect thing. And the only thing bothering me was, how can they deal with latency so perfectly? I mean that's one of the major challenges when dealing with shared data. And if there was no problem with latency with current technology, then existing systems can also work equally well.
    Secondly, what about scaling? Where would all the data go? In the age of cloud, where there's a probability that even OS would be in the cloud and we'll be just holding devices, there's a concept that all the world's data would be in our systems? Not possible of course. And if only some peers will handle it, then we're again back to where we're coming from.

    But this video explains the goods of blockchain, and how there are some challenges which they're trying to deal with.

  42. Great video, but I don't understand the comparison between Bitcoin and Visa. Bitcoin is a currency, not a bank, you can trade it directly but normally you would do it through some third-party service just like Visa or Mastercard does for the USD and other traditional currencies, this solves the latency problem.

  43. Great interview. She almost sounds like she reads off a well-written script (in a good way). So now that there are "blockless" DLTs like the Tangle that in theory get rid of some of blockchain's issues like the mining, centralisation and scalability problems, can we have Dr. Bano do a piece on, like, the future of blockchain? 🙂

  44. Hi Im loving the video , but that pencil sound with the paper is killing me … aggghh , i have to say i love the issue, the explanation is really clear and also love your channel. I have some questions … if we want to have a server (database) using blockchain tech , i know it wont be a classic centralized server , but my question is … as we put more info into the data base , the chain gets longer and harder to solve? is there a limit? … is the limit the capacity by the minner's nodes to solve the hashes ? if the calculating capacity of the nodes get increased it makes the system could keep growing? also love to know if this system is moore secure than RSA codification, because if it is, and also is open source … will be nasa getting really mad?

  45. All seems to go back to the mining. Current estimates are that energy cost of this apparently futile activity are greater than the entire energy budget of a country like Ireland. It is like a cancer of the collective processing power of the planet.There is no real value here, it is fabricated out of nothing

  46. To implement an electronic voting system on a blockchain infrastructure u need to address the issues 1.)the validation process of the voters and 2.)by doing that keeping the anonymity of the voters as well.

  47. Proof of Stake blockchains scale much better than Proof of Work blockchains, because in Proof of Stake every wallet can create blocks, you don't need hashing power.

    But still people keep thinking that you need to waste huge amounts of energy to "mine" blocks.

    The committee approach has been tried with masternodes but that's also not a perfect solution because it decreases the decentralisation in the network, creating an elite of nodes that decide more than other nodes.

  48. The more I learn about bitcoin and blockchain the less I think this will ever be able to scale to the requirements of a widely used currency.

  49. After watching this video, I realized that Dash network is already using this aproach. They have master nodes that confirm instant sends. It's required to have 1000 dash to be master node. Master nodes splits their work, only 5 master nodes confirm an instant send.

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