Probably nothing, but that depends on your definition. Let’s look at the technicalities.

You have a number of crypto transactions that are bundled together into a block. Then you compute a hash - a checksum - for this block. If the data changes, then the checksum no longer matches. The trick that makes it a chain is to include the checksum of the previous block in the next block.

If someone manipulates the transaction history, they need to recalculate the checksum to match. But then they also need to change the following block and recalculate its checksum and so on.

This is a pruned down version of a Merkle Tree, which was thought up ~50 years ago. It doesn’t have to be a chain. You can allow a block to have more than 1 succeeding block; making a fork. Blockchains are one use of that data structure. Wikipedia lists some others. Git, for example, also uses this.

The bitcoin maker knew to use this trick when he needed it. When Torvalds wrote git a few years before that, he also knew to use it.

When you ask about Blockchain specifically rather than Merkle Trees, you greatly limit what can be done with it. So there aren’t a lot of uses left. Most people would say that a Blockchain is more than just a limited Merkle Tree. When you add in those features, you make it even more specific to the original application. So you are probably left with just crypto.

Cryptography based Banking
There are lots of good reasons to not base money transfers on arbitrary numbers that you need to keep track of. Right now, banks have to make sure themselves that a transaction is legitimate and may never lose record of it, otherwise money just disappears to someone’s damage. With a blockchain, you get a hard proof a transaction took place. Whether that’s to proof you paid for something or for law enforcement to know you bribed a certain someone, I firmly believe it’s better than what we do now. If my bank told me tomorrow I have no money or claimed I spend it all on terrorism, I would be in a pretty bad spot.

Ownership and Track Records
We live in a time of misinformation and AI generated bs. With the help of a blockchain, you can keep track of who posted something first, i.e who has the copyright or started some false information campaign, and also who generally spreads bs. This of course also works the other way around: Who has a good track record and posts trustworthy news or original content? And again, you wouldn’t necessarily have to rely on a single institution to play nice, not delete content etc. Although admittedly, it’s much more complicated this case, because you have to expect bad actors much more than in banking. Banking is infrastructure, this can be a lot of things (science and/or opinion and/or legal stuff…).

No

Fine, I’ll elaborate a little more.

Blockchain generates typically with huge cost and inefficiency a decentralised ledger of events. If you are going to use a blockchain you need to ask yourself tow questions. 1. Do I need a decentralised ledger/record of events and, 2. Am I willing to put up with the huge increase in costs for creating said ledger.

In my opinion there is nothing that satisfies these two requirements. Blockchains can not remain decentralised for anything that interacts with the physical world as some needs to input the data in the blockchain. This requires you to trust a party destroying any notion of decentralisation (i.e. if an entity can control what goes into a blockchain then it really isn’t decentralised).

Following from this if you are willing to accept and trust a centralised actor to control what enters your blockchain why not trust them to manage your ledger. It would be simpler and easier than using a blockchain.

Finally, as for digital goods that don’t interact with the physical world. Why do you want to introduce a decentralised scarcity? It’s a silly idea. Either you own the intellectual property and you decide who has a license to use your digital goods (in which case you don’t need a blockchain) or you leverage some of the best attributes of the digital world and you leave the good to be freely copied, downloaded and used. A blockchain is just a wasteful unnecessary exercise at that point.

Basically there’s no legitimate use case for blockchain. The best proof of this is just how little real world adoption blockchain technology has in the real world. It’s as old as the iPhone and yet I don’t know a single person who uses it to get things done in their day to day lives. If it had a use we would have found it already.

Let’s first state what the blockchain states it is:

• immutable
• public
• decentralized

Let’s say that you’re a user who wants to use the blockchain to manage something outside of the digital world with it. You create your product, and begin advertising it. No matter what this product is, it cannot affect the physical world. This means that immutability is a problem. The real world has mistakes. If a person sells their car, they need to hand over cash in the real world. How does that knowledge make it onto the chain? Same for a house, etc. Any object that has a transaction in the real world has to have an authority that manages whether that object has actually changed hands. So for the simplest use case, the chain has already failed.

Let’s talk about the next one: public. Nobody wants their transactions public. You don’t want votes to be public. The blockchain is not anonymous, no matter what anyone claims, because every record is tracked you can eventually deanonymize anyone if you wanted to. So this one is just a bald-faced lie and something not to be desired in any situation. The point here was to make it so that you can be decentralized and the public can be the ones to police others users of the chain, so let’s talk about how it’s fundamentally impossible for a chain to actually result in a decentralized world.

The blockchain is not actually decentralized. If you want to handle money in most countries on earth, you have regulatory bodies that govern everything about your operations. That means if you want to write an app like Shopify that someone can use to pay with bitcoin on a website, even if you are not selling something physical, you are still governed by a central body. Not only this, but once you want to sell something physical, you have to extract your money through a physical bank in the real world, which is also governed by the same regulatory bodies. This was immediately known as a problem in the early days of bitcoin and other cryptocurrencies, and it is still a problem today. This problem is not solvable as long as governments exist.

Funnily enough, each one of these elements does have use by itself! For example, distributed databases have been around for decades, and are the basis for much of the tech you use today. There are even immutable databases that are in use in many industries to keep an immutable record of what happened. AWS is sunsetting it now, but their QLDB was exactly that. CQRS with Event Sourcing is another implementation of the same idea. Finally, any government service or company could make records public if they want to. In fact many already do, for example home ownership records. If you own a house, that information is not private.

Putting something on the blockchain is no more than a move to make sure whomever owns that crypto gets more money out than they put in. If an actual use case existed for this tech, it would have been used decades ago when it was first invented (the blockchain was actually invented in the 80s by cryptographer David Chaum, decades before Satoshi invented Bitcoin and it was even discussed in Satoshi’s whitepaper).

I can talk for hours about how each element of the blockchain is just either a grift to extract money from others OR a cynical, incorrect outtake on how the real world functions. If you want that, let me know.

I like git, most used version control system around these days. The way in which commits are hashed is very much a blockchain.

I also like public timestamp services, which are also often implemented as a blockchain

This looks interesting https://github.com/ortegaalfredo/blockchainbay

Disclaimer I have not tried it , just discovered it now

The most attractive part about blockchain is the decentralized ledger showing each transaction made.

I feel like greater minds than mine could come up with a way to use that to fight government corruption. Every transaction is a matter of public record.

I doubt it’s really a practical solution though. Each transaction makes each subsequent transaction more computationally expensive. Plus all these vendors and contractors and everything are accustomed to fiat currency. Likely, they’d just immediately exchange it for cash.

This of course doesn’t tackle the issue of under-the-table corruption where you invite a senator out for lunch and kickbacks. I’m also sure that the government would want to maintain their own ledger, or that conniving people will find a way to cook the books anyway.

Private transactions, despite what people here are saying. Let me explain:

1. Privacy is not equal to anonymity. The latter is much harder to achieve.

2. There is Monero, a crypto made specifically for anonymity. It’s not very convenient to use, but it is preserving anonymity with multiple measures.

3. Even Bitcoin, which is not built for that purpose, is private enough. It depends on how you use it.

4. Deanonimization in general happens when you link your transaction with personal identifying information, but you can reduce your exposure by following certain opsec rules. I see this situation is better than traditional banking where your transactions are always not anonymous, and privacy is only protected by the bank itself. Data leaks happen, governments can get to your transaction info via legal means, but with crypto you have more options to protect yourself.

I’m going to say “no”, at least in the practical sense.

Before “AI” was the current hype, there was an equally annoying “Blockchain all the things” hype (and associated cryptobros partially fueling it). Aside from the various crypto scams, I’m not entirely sure if/where it found its niche. The fact that everything today isn’t running on blockchain like the hype of yesteryear predicted is pretty solid evidence that it wasn’t all that it was cracked up to be.

I’d say in theory it could be used something like public records of proof for ownership of immaterial or intellectual property and the transfer thereof. Say the rights to music, writing, digital art and whatnot. Like the essence of NFT without the hyped up crypto bro speculation and pump’n’dump.

The difficulty would be to get it recognized as legally valid and the bigger difficulty that as there is no central authority there is also nobody being able to rectify fraud or user mistakes. If you implement central authority it’s basically just any old list of transactions with some extra crud so then the question would be why even bother.

It’s not even good as a bank. On the other thread you mentioned I commented that blockchain is an immutable ledger visible to everyone. That is a nightmare for privacy reasons.

Audit logs is genuinely the only application I see it may be good for, but we have other systems that have a smaller environmental and technical impact making them a better fit than blockchain.

The general category of potential use case is when you want some information to be public, undeletable, and outside of corporate or government control.

While I can’t think of a compelling use case at the moment (other than whistleblowers, maybe), given the direction our corporations and government are going it seems like the sort of thing that might become increasingly useful in the near future.

Its only real use is as dark money. Which isn’t always a bad thing - there are a lot of activists in oppressive countries who rely on bitcoin donations, Anarchist Black Cross comes to mind.

But, as you said, it’s not really as “dark” as people think.

I seem to recall someone developing a “game” that was based on the blockchain but used to crowdsource protein folding models or something like that? I could be mixing two memories though. I could see how the concept could possibly be implemented for something like that, but I wonder if it couldn’t be handled more energy-efficiently by like a single quantum computer doing calculus.

You can check out the use cases on hyperledgers blog. E.g. https://www.lfdecentralizedtrust.org/blog/energy-mines-digital-trust-the-future-of-global-supply-chains

Just fraud. Nothing else.