I think you lost the context there. The essay is about proof of work, not immutability, and that’s why he doesn’t make any claims regarding other methods of providing it. My comment about the point he’s making in regard to the lightning network is in relation to your words “Sure, lightning network is coin-agnostic, but it doesn’t change the need for blockchain immutability.” - the coin-agnosticism is exactly the point; it has implementations in other coins that do not use proof of work for their blockchain. That is explicitly in the critique.
Which flows into:
So either you are contradicting yourself by positing that those blockchains are mutable due to not using proof of work, and therefore lightning networks do not require immutability for implementation; or, you are conceding that proof of work is simply one manner of providing immutability rather than the only way, which is exactly the argument Gerard has made to dismiss using the lightning network as a defense for proof of work’s inherent inefficiencies.
They’re very related concepts though. The only thing that POW does and the only reason it exists is to guarantee immutability. So it does seem reasonable to consider the concepts together.
I definitely agree that POW is only one way of guaranteeing immutability. We’ve got proof of stake, proof of storage, and other even more speculative approaches being researched now. It’s totally possible that one of these new proof systems is technically superior.
It’s also possible that they aren’t though, we don’t really know yet. And in a real-world implementation, users are primarily interested in the strongest proven guarantee of immutability. What system is the most proven when it comes to guaranteeing immutability? This becomes hazy, because it’s possible to speculate about the possible ways any system could fail in guaranteeing immutability. But looking at real-world performance, the general consensus does seem to be that POW is by far the most dependable system available - i.e. it’s at least in beta where other proof systems are in alpha.
So I hope that some other approach to immutability comes along and usurps POW, because obv there are a lot of things that suck about it. But it seems, i dunno, like wishful thinking or something to just assert that POW is unnecessary. That will need to be demonstrated in practice before the assertion holds any weight. And until then, it’s understandable that users will tend to prefer having their transactions processed by a POW-backed lightning network as opposed to a POS-backed lightning network.
I think that’s exactly right. Ethereum is experimenting with a Proof of Stake algorithm, And Stellar uses a consensus algorithm. To name a few alternatives. Both of these ideas work, require orders of magnitude less computing power and have a much higher throughput than PoW algorithms.
Both PoS and consensus algorithms have their downsides, but I think one or both may become viable alternatives to PoW.
ETA: The algorithm used by Stellar is actually called Practical Byzantine Fault Tolerance.
No, the Dollar very clearly evolved. It is just an incarnation of money as used by countless nations before, with the expression and meaning and features constantly changing. Even the name comes from the German word “Taler”, which refers to silver coins from the mining town of Joachimstal.