While I agree that only increasing block size forever (or simply removing the size limit) doesn't seem reasonable in the long run, are we sure that segwit and the off-chain scaling solutions proposed today will really solve the long-term scaling issues of BTC?
The Q-and-A at the end in particular is interesting:
>Q: On the last slide, one of the assumptions was 3 channels per person. Assuming payment channels wouldn't be useful for retail sales, because you don't want to buy a coffee just to open immediately. Is that correct?
>A: Joseph might expand on this. Let's say you buy a coffee. You're probably buying a coffee only once, right? Well, maybe the coffee is $5, and you put $50 into the channel and leave it open. Then someone else comes to the coffee shop and she does the same thing. But she has a channel with the grocery store. There's me, coffee shop, Alice, grocery store, they all have channels. When I go to the grocery store next time, I don't have to open a channel. Payments are routed.
>Q: It sounded like everybody would have to open new channels.
>A: I am guessing the mean is going to be 3, but it will probably be an exponential distribution. Most people will probably have 1 channel, and then some might have 100s of channels open.
I don't know about you but while on paper that might work I still see a lot of hand waving, guesswork and rather unsubstantiated assumptions. Why would I decide to "lock" $50 worth of Bitcoins when I buy a $5 coffee? What's the incentive for me to do this? Where does this estimate of 3 come from exactly, I see it repeated everywhere but I can't find the maths behind it?
The simulation is rather unrealistic and I'm not sure how to interpret its conclusions. It seems to kinda work but there are issues:
>133,401 micropayments were attempted and 3461 (2.6%) of these failed. For successful payments the median number of hops was 19 and the median total fees were 2 bits (0.000002 btc) or 32% of the value transferred.
Now it could be caused by a bad simulation rather than a real issue with Lightning network, but frankly I can't tell at this point.
I don't have a horse in this race but as seen from the outside it all looks a bit rushed and amateurish. I don't know the whole story though, maybe I'm just poorly informed.
The simulation starts with each user having 14 channels open - seems like quite a strong assumption for a serious test (starting with 0 channels for each user and then randomly opening new ones would be much more interesting). After a talk by one of the lightning devs I also got the impression that they are betting that several hubs with thousands of channels would quickly emerge - due to the fee gained by running a channel. Needless to say this would undo quite a bit of the decentralized nature of bitcoin.
Seems like a good deal for the coffee shop (you don't have to pay for the Visa fee and you get some free customer retention on top of it all) but as a customer what do I gain from that, practically speaking? The only thing I can think of is low fees if I'm traveling abroad. But if the fees are really very low then your incentive becomes void, I won't bother putting $50 in the coffee shop if it only saves me $0.001 in fees.
Can you really imagine how this would work IRL?
"-Here you go sir, that'll be $32 please."
"-OK, I'm paying it Bitcoins... Oh, you don't have an open channel, I'm going to create one... Mmh, but how much to I put in? Let's say $100, I'll probably buy here again next week. But will that be enough? What if my total is just above that next time? I'll have to pay the fee twice. I guess I'll just make sure not to go over $100."
"-We also accept cash, Visa and MasterCard sir."
Again, maybe it can work, it just feels so "theoretical" so far, I haven't seen anybody paint a convincing picture of a what a "Bitcoin as Visa replacement" world would look like concretely.
You missed a really important feature of lightning. If you have a channel open with Starbucks, and Starbucks has a channel open to Wal-Mart, and Wal-Mart has a channel to $local_bank, which has a channel to $local_store, then you can use your Starbucks channel to pay $local_store.
And while this is an important feature of lighting, it's not actually a "feature" when compared to Visa or MasterCard and the centralized banking system from the point of view of the user. Ideally this should all be hidden away from the average customer.
People won't want to worry about graph theory when paying for a sandwich at a gas station. Existing payment solutions still wins hands down 99% of the time when it comes to convenience even if we imagine a "perfect" lightning network. I really have a hard time imagining what would drive a mainstream adoption of bitcoin over the current status-quo.
Users don't need to worry about routing when they connect to the internet, though in fact the computer is making 10+ hops for any given connection.
Lightning will work the same way. Nobody needs to worry about graph theory, they can just generally assume that the graph is fully connected, and that their software will be able to find a path from A to B.
The internet is not decentralized the way Bitcoin is. Actually I'd argue that the internet is more like the modern banking system: you have big corporations (ISPs, Google, Facebook, Netflix, Amazon...) interconnecting to provide a service to users in exchange for money. They have a vested interest in making sure the network actually works, at least for them. If you want to use the Visa payment system you need a bank account, if you want an internet connection you need an ISP. Bitcoin has nothing like that.
What will be bitcoin's "ISPs"? Who makes sure the graph remains connected and usable? Who invests in the "infrastructure", making sure channels remain well balanced? Some say that Lightning will be self-balancing through a clever set of incentives, but that's again extremely experimental and untested.
Also note the big "net neutrality" thing going on in the US right now. What will prevent big players from teaming up and interconnecting with each other to facilitate transactions while leaving out the rest?
I don't have the answers to any of these questions, maybe it's just FUD. I'm just surprised that bitcoin is a couple of weeks from making such a huge jump into the unknown. It's extremely interesting to be sure, but I feel like some people are going to get severely hurt if this whole thing comes crashing down.
I don't see a reason that exchanges couldn't take on the role of ISP/bank in this situation. Essentially you have an account with 1500 BTC at an exchange, and you say that you want to put 500BTC into a lightning network. Then the bank centralizes itself in the lightning network graph by making connections with other large banks and some major companies.
Of course what we've just done is recreated the modern centralized payment processing scheme on top of the bitcoin network (ie. a mom and pop shop connects to square connects to BoA has my money which doesn't actually exist anywhere, and they make ledger changes and top up later).
You might even be able to make such a system work with no additional transaction fees. But I'm not sure of that.
Why not just use Stellar or Ripple at this point? That's exactly what it was designed to solve. And it has the benefit of being able to use, you know, real currencies. So you can go to your coffee shop, instantly spend $5, and be done without having to worry about what the price of a bitcoin (or in this case, lumen) is.
Yes. This is basically the exact user experience of the Starbucks app, and it's a fine experience.
You pre-pay an amount, have a balance open, transactions reduce that balance, and you occasionally need to reload your balance with another credit card transaction.
Which is to say I don't think this is an intractable problem if there is good software with good user experiences to help out.
All that said, I'm not current on the block-size vs SegWit debate, so my analogy could be flawed.
But Starbucks is the perfect use case for this Lightning scenario, it's a frequent purchase for a relatively small amount. Basically anywhere where a "voucher" system like this starbucks app exists lightning could probably fit with minor disturbance.
Now take amazon, take that small shop on the street where you go twice a year because it's super expensive but it's also opened very late, take your car mechanic, take that guy on ebay you're buying a pair of socks from, take that restaurant in Berlin during your vacation where you'll probably never go back. Will you be willing to "pledge" 10 times the amount while buying there? And if not won't the fee be dissuasive? What's in it for me?
And won't that create negative side effects for competition? For instance if a new coffee shop opens next to Starbucks with your system I have an incentive to keep going to Starbucks since it already has an open channel (exactly what the Starbucks app is about, except I'm paying for it, not Starbucks), so effectively it makes it harder for newcomers to compete. Same thing for, say, amazon vs. some random ebay seller. The more popular a shop, the more likely it'll be to have an open channel pending. Isn't that going against the "completely decentralized currency" ethos? What good is it that the currency is decentralized if I can effectively only use it with a limited number of companies?
It would be pretty amusing to me to see the cyberpunk libertarian cryptocurrency turn into a glorified Costco membership.
All the practical "here's how lightning's going to work" papers I've read so far leave me very skeptical. Here's an example: http://diyhpl.us/wiki/transcripts/scalingbitcoin/hong-kong/o...
The Q-and-A at the end in particular is interesting:
>Q: On the last slide, one of the assumptions was 3 channels per person. Assuming payment channels wouldn't be useful for retail sales, because you don't want to buy a coffee just to open immediately. Is that correct?
>A: Joseph might expand on this. Let's say you buy a coffee. You're probably buying a coffee only once, right? Well, maybe the coffee is $5, and you put $50 into the channel and leave it open. Then someone else comes to the coffee shop and she does the same thing. But she has a channel with the grocery store. There's me, coffee shop, Alice, grocery store, they all have channels. When I go to the grocery store next time, I don't have to open a channel. Payments are routed.
>Q: It sounded like everybody would have to open new channels.
>A: I am guessing the mean is going to be 3, but it will probably be an exponential distribution. Most people will probably have 1 channel, and then some might have 100s of channels open.
I don't know about you but while on paper that might work I still see a lot of hand waving, guesswork and rather unsubstantiated assumptions. Why would I decide to "lock" $50 worth of Bitcoins when I buy a $5 coffee? What's the incentive for me to do this? Where does this estimate of 3 come from exactly, I see it repeated everywhere but I can't find the maths behind it?
Here's an interesting attempt at simulating a real-scale ligtning network (why aren't there more of these? Aren't we talking about a $40bn market cap currency here?): https://hackernoon.com/simulating-a-decentralized-lightning-...
The simulation is rather unrealistic and I'm not sure how to interpret its conclusions. It seems to kinda work but there are issues:
>133,401 micropayments were attempted and 3461 (2.6%) of these failed. For successful payments the median number of hops was 19 and the median total fees were 2 bits (0.000002 btc) or 32% of the value transferred.
Now it could be caused by a bad simulation rather than a real issue with Lightning network, but frankly I can't tell at this point.
I don't have a horse in this race but as seen from the outside it all looks a bit rushed and amateurish. I don't know the whole story though, maybe I'm just poorly informed.