The scaling part starts at 13:13

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

She gives a good interview. Well thought out. Interview her again!

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 KZfaq channel, much like her fellow Computerphile alumnus Rob Miles.

I could listen to her speak all day. Clear, conscise, informative.

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!

Just found out my .28¢ worth of bitcoin I got a while ago has turned into $8 worth. Not bad.

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.

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.

She's very eloquent. Great interview.

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?

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 ;-/ )

This video has more than tripled its value over the last 15 hours.

I've got to say, this topic is massively interesting and the video was awesome. I was totally glued to her every word. Thank you numberphile!

Yeah, block chains scale up linearly. More transactions require bigger blocks, this is why all the focus is developing off chain settlement so that we can take 99.9% of transactions off the blockchain.

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.

Sheharji the way you have explained, I got reminded of my friend who used to teach me in college...plain, simple and in easy language

Nice! One of the best, well laid out explanations on blockchain that I have heard so far... for my level of understanding I mean.

Love that "Practical Visual C++ 6" book on the shelf.

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.

do an episode on zk-Snarks next!

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

Simply the best video on blockchain description ever!

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?

Very good explanation. 10/10 ! Thank you Dr. Bano!

If the question is blockchain scalability, why not discuss storage constraints? This is especially an issue with something that's transacted as often as a currency.

This video is simply amazing about many of the issues which needs to be addressed due to lack of scalability of bitcoin desgin and blockchain technologies. As it passed 5 years, it could be good an update video of what has been solved or changed since then.

Transactions don't include block ids (hashes) when referring to previous outputs, they include transaction ids.

Seriously thank you for putting up videos like this its really helpful , and the Dr explains things really well .

Very Informative

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!

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?

Great video. Really cleared my concepts.

I like to hear her talk, shes intelligent and very nice to listen to. Thanks for all the info!

Well presented in an easily understood manner. Very informative. Thank you!

I think this woman seemed a bit nervous at first, but got into it quickly! Very nice good video!

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.

What's your take on PoC (Proof of Cooperation), used by Faircoin?

Couldn't those "leader" nodes just be an alternating committee, and not a permanent group? That was collusion could not really be possible.

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?

The best blockchain explanation I've seen.

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?

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.

awesome video on blockchain scalability. very thorough and informative! computerphile ftw 😎

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.

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.

The annotations at the end of the video, which link to the Krack attack and botnets, are missing. Great interview btw ^^

If you have to wait for a few blocks to be finished after you submit yours... just to know that it is final, doesn't that imply that your submission could be lost? How would this happen and isn't that a big problem?

Very clearly and beautifully explained. Thanks!

Fantastic discussion on the topic. Thanks!

More Dr Bano!

this video just answered all my questions about the block chain thank you

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?

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.

I think I finally understand it at last! :)

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.

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?

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?

Very nice explaination... for convoluted concepts of BlockChain technology

Brady could you please do a video about Monero? The Monero blockchain is encrypted and that's pretty damn cool.

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.

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

We need scaling on second layer, sidechains => Lightning Network. Blockchain will become a settlement layer.

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.

Solid explanation. Thank you.

The blockchain is currently 65 GB. I don't have the disk space to use my wallet?

Excellent explanation!!

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.

great video, thanks to this promising scientist

Very good explanation , thanks!

Clear, deep and accurate!

Some blockchains have a 15 second block time instead of 10 minutes. How does that work?

That was great. Thanks for sharing

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.

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.

Informative, cheers.

Very nice video!

Thats was the topic of my thesis! :D

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.

13:05 what study is she referring to?

Awesome video !!

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.

Lady has done her homework, thanks for all the info.

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.

How blockchain pruning impacts on the scalability concerns

GREAT! THANKS FOR SHARING IT

Fascinating

This was good but I miss the brown paper.

She killed that.

It's not Charlie, it's Bob!

I see an other huge issue with block-chains' scaling in numbers as people want to use more of them for various uses. The integrity of block-chains relies on the race between "miners" but if any one "miner" has overwhelming computing power compared to the others, it compromises it. For example, let's say there are a 1000 different block-chains. That means at least half of the block-chains have less than 0.2% of the worlds mining power devoted to them. So if one miner with 1% of the worlds mining power were to focus on a weak chain, they would be able to compromise it. That means at any given time, there is a limited number of reliable block-chains, depending on how big a share of the mining power the biggest mining entity has. If the biggest mining entity has about 1% of the world's mining power, that means you can probably not have more than 50 different reliable block-chains in the world. And since the throughput of a block-chain is limited as explained in this video, that means the overall uses of block-chains are very limited.

Great! Have been waiting for this episode

We need an update :-)

Interesting.

Almost matching the 9th anniversary of satoshi's white paper :)

There is a decentralized concensus about the quality of this video :)

finally an interesting topic real video starts at ~11:00

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!

Thumbs up for Visual C++ 6

GOOD VIDEO