There are lots of other approaches - IOTA DAG, HashGraph, Ripple Consensus Process etc.
I am not a fan of blockchains, though. They are overkill for most uses. But here is an example of a non-blockchain system that doesn’t even require global consensus:
It's not really going to work. Without a centralizing consensus, any such scheme is vulnerable to be drowned in forks.
A malicious notary network can simply flood the ledger with conflicting views. So clients will have to somehow find a set of notaries that is the "best".
Proof-of-stake means that there's effectively a vote on the set of "reliable" agents, and proof-of-work works because the malicious notaries can't outrace everyone else.
Sorry, but you're not exactly an expert on this. There is a huge body of literature that says otherwise, and reference implementations.
You don't NEED "a centralizing consensus". IOTA did have one, called a "governor". And now they also did away with it.
I had a discussion with the CTO of Ripple (back then their chief cryptographer) David Schwartz about this exact issue in 2018, when I was also connecting with Leslie Lamport and others in the industry to discuss why and how global consensus was even needed
Yes. How do you find a notary that is not malicious?
A malicious subnetwork of notaries can flood it with bogus transactions. To prevent that, you have to make sure that transactions can't happen without a significant expenditure of real-world resources.
That's not true. Notaries shouldn't be able to flood a network at all. Each participant in the network is supposed to stop accepting messages from a malicious participant. It's one strike and you're out.
That's what Proof of Corruption is about, in our technology, for instance.
Every participant has to sign their claims. If a participant signs two contradictory claims, this Proof of Corruption can be gossipped and the participant is excluded.
In distributed systems, 99% of the time you have finality, but 1% of the time you may have a conflict due to race conditions or corrupt nodes, etc. Blockchains take the unfortunately brute force approach of gathering all the conflicts / ambiguities into one or another consistent chain of transactions, and then "duking it out" with a lot of expensive "stake" or "work" or whatever. But it doesn't have to be that way. The end-users are ultimately the ones to either endorse a transaction or not, there is no reason to have the network be the source of truth for the remaining 1%, there are hugely diminishing returns from all that waste of electricity. So even the double-spend problem can be solved without blockchains.
But even without this, in other decentralized architectures such as the PTN (Permissionless Timestamping Network) I linked you to above (https://intercoin.app/technology.pdf) there is no blockchain, no consensus, just nodes talking to each other and data structures accruing in eventually-consistent ways. And the nodes can just as easily stop listening to you and forwarding your messages.
Similarly in the SAFE network. Even the routing is done in a way that the routing info is deleted after one hop, so you can't DDOS the network the way you can a regular IP / BGP network or even a regular DHT (such as Bittorrent's Mainline DHT). Because the nodes will just refuse to pass on your message. Every node expends only the resources it is prepared to, and nothing more. This idea of "flooding" or "DDOS"ing is more of a legacy idea due to the federated systems we have today, like email and DNS (where the whole world can spam a person's email, and you play cat-and-mouse).
Again, blockchain is a tiny part of this space of decentralized networks. You can have CRDTs syncing, or you can have append-only logs such as Hypercore (now called Holepunch / Pears) or you can have Freenet (the new one, I interviewed the founder a couple years ago when it was still called Locutus: https://www.youtube.com/watch?v=yBtyNIqZios) you can have Secure Scuttlebutt, or Nostr etc. etc. etc.
> The end-users are ultimately the ones to either endorse a transaction or not, there is no reason to have the network be the source of truth for the remaining 1%
> And the nodes can just as easily stop listening to you and forwarding your messages.
You're describing a willingness to incorporate a respect for user consent/participation into the design of your protocol. I think that most people who are enthusiastic about blockchains are not willing to do that.
It's not a technology thing, it's a power thing. They don't want coordination of this kind to be compatible with per-transaction user consent, because if it is, then any system which preserves that consent will be more legitimate than their thing which doesn't, and that's bad for their investors/investments.
Conversely, it's hard to find investors if you're building something that leaves users with enough freedom to insulate themselves against a particular remote influence (such as the investor), which is why the blockchain people have a bit of a head start here.
Blockchain's early applications have been derailed by greed and stupid applications like meme coins and rug-pulls. Instead of leveraging the power of smart contract factories using the Factory Pattern, teams started releasing one-off contracts, and others gambling with them. This led to zero-sum games at best, and negative-sum at worse (for contracts with bugs or rugpulls). Compare something like UniSwap (which is a factory) to a random contract based on "SafeMoon" or "EverRise". The UniSwap pools all have the same trusted, audited, battle-tested code. It's the kind of stuff I am a fan of.
Going further, many COMPLETELY NON-BLOCKCHAIN enterprises, like FTX and Celsius, ruined the good name of Web3 even further, which is around Smart Contracts. Think of it like the Web2 tech bros and VCs trying to make a buck around Web3. YC-funded companies like OpenSea have been better actors, but many wallets etc. ended up using them and gateways like Infura as the source of truth, almost obviating the need for Web3.
Having said all that... I've been discussing this more on the applications and UX level. Users always have the power to switch away to a fork of something, and migrate away from an ecosystem. But a good ecosystem can "earn" its lock-in by giving them stuff they want. That's what happened with all the centralized Web2 platforms undergoing "enshittification" due to the profit motive.
So yeah, capitalism and greed have derailed a lot of Web3, but in a different way than Web2. It's why I built https://intercoin.org/applications . Look at https://intercoin.org/deck.pdf for what Web3 COULD be like. We call it Web5 to get away from the morass which is Web3.
Now, back in 2018 when I started it, I was planning to build a post-blockchain network, and I still do. It's going to be called Intercloud (a portmanteau of two words like BlockChain). But besides blockchain, there are HashGraph, IOTA DAG and others.
So yes, blockchains have a head start mostly due to the profit motive. Same with centralized Web2 social networks. You don't see HN being against those very much, but they are vehemently against Web3. I consider Web2 to have been completely ruined by megalomaniacal tech bros and VCs out for profit, and society at large has been harmed by it. Here is the diagnosis and the solution:
(Over the last decade, I have spent the majority of my own resources, without VC, building an alternative open system. I've been sort of marvelling at how actively some HN users are against it, and often knee-jerk trying to downvote it because it contains words like "decentralization" and it can interoperate with Web3... but I am confident that once it goes mainstream, suddenly some people will look back on all my posts and finally get it).
I am not a fan of blockchains, though. They are overkill for most uses. But here is an example of a non-blockchain system that doesn’t even require global consensus:
http://intercoin.org/technology.pdf
Also check out the Autonomi network