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Comment by sfjailbird | Hacker News Reader

Isn't BTC privacy achievable these days with coinjoin, lightning network etc.? In that case no much reason for monero.

It still seems fantastical to me that lightning network is presented as "something running on BTC", when it is "something running completely separately, instead of BTC". Transactions on Lightning network are not transactions on BTC, and have none of the guarantees of BTC (and in fact have no reliable guarantees of no double spending).

The only way to get BTC-like guarantees of no double-spending for Lightning network transactions is to put every transaction on the BTC block chain ("close the channel" after every transaction). And then, of course, you get back all of the problems of BTC (minuscule TPS not enough for a small village, 0 privacy, huge energy costs).

If what tsimionescu says about Lightning is wrong, can somebody kindly reply to them explaining why rather than just downvoting which doesn't help anyone. (Maybe there's a reason they were downvoted that isn't their being wrong, but I don't see what that would be.)

(And sorry for going against the guidelines and talking about downvotes, but I'm really just asking for someone to either confirm what they said is right or explain why it isn't, I'm not caring about the votes themselves.)

See https://blog.breez.technology/lightning-btc-iou-62e3a712c913 for instance.

As that post makes clear at the end, if you don't monitor the BTC block chain actively (with an app or by paying a third party you trust to hopefully do it for you), you can be cheated out of your BTC with Lightning.

not a downvoter, but a criticism is yhat BTC doesnt actually offer defenses agaisnt double spend, at least when you use it to buy something.

if the chain swaps a month from now and drops my bbq purchase, the bbq shop isnt getting their bbq back, even though i get my BTC back on the new chain. the ethereum fork for ethereum classic also doubled everyone's wallets, which i'd consider to be a double spend

The double spend protection is quite limited, so whats the big loss from lightning?

First, if people didn't believe that BTC protects from double spend, then it would not be used by anybody. Secondly, the whole point of the proof of work scheme is that it's impossible, or at least extraordinarily costly, for anyone to outrun the main chain enough to publish a new block that replaces blocks from a week ago. It's in fact considered impossible for blocks from an hour or so ago.

So, assuming the BBQ supplier waited about an hour for confirmation, the chance that the money would be lost is minuscule with BTC transactions. With Lightning transactions, the same is not true at all - the customer could close their channel abruptly two months later when the BBQ joint is on vacation, and the money would suddenly vanish forever (assuming they don't catch the fraud in the time window before it becomes permanent).

Of course, in both cases, if you're the person who sent the money and the BBQ never arrived, you're out of luck entirely. Which is why the claim that BTC or Lightning enable trustless monetary transactions is mostly bogus, even with a no-double-spend guarantee. And waiting one hour for a payment to a BBQ joint to clear is basically unworkable (and the reality is more like two hours - one hour for the transaction to make it to be mined, and the other hour to confirm the block where it was included remains permanent).

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