[melkiaur]

There's one I like: the farmer has a veal and introduces its date of birth on the blockchain.

The veterinary that comes to check it posts a validation mark on the blockchain. If you trust the veterinary, you should trust the birthdate.

The veal grows up to become a cow, and is sent for slaughter. The farmer stores an event on the blockchain and sends it to be cut into meat.

The slaughterhouse stores an event (with the weight) on the blockchain and sends it for distribution.

The butcher creates the packets of meat, with a QR-code which lets you check the whole list of events, with their dates and places, and of course, you can check that the same part of beef doesn't end up in two different shops. You have complete traceability of your meat despite all the actors not knowing each-others.

[danielmg]

That's already a solved problem in the UK after the BSE crisis. From what I was told (by a friend who worked on it), it uses certificates to provide trust and verification. Uses a central database hosted by DEFRA. No blockchain needed.

https://secure.services.defra.gov.uk/wps/portal/ctso/

Everything you describe can be solved, in a better and more efficient way, by non-blockchain technologies.

[GauntletWizard]

Part of this problem is that signed merkle trees are the solution to lots of problems, and block chain advocates say "Those are blockchains!" and then try to introduce the undesirable feature (forward looking hashes that require proofs), while crypto nuts have already been screaming about merkle trees forever.

[melkiaur]

It could be solved, but is it really ?

Shall I remind you of this: https://en.wikipedia.org/wiki/2013_horse_meat_scandal#UK_Inv...

The blockchain doesn't offer a technological solution that couldn't be done with a centralized authority (I particularly like the way passports rfid reading involves certificates signed by each country). But it offers means to achieve that even if nobody safe enough wants to host the bloody service.

[danielmg]

That wasn't about the provenance of the meat but the production of the end products - e.g. pies etc. They were just dumping in bad meat in place of good.

Blockchain isn't going to solve that - you could put the ingredients in the on it and have them signed etc but at the end of the day humans are mixing the food.

[dmitriid]

Someone marks horse meat as cow meat on blockchain. How exactly blockchain solves that?

[hnbroseph]

ot, but even as i would probably be a little dismayed to learn my burger wasn't made of what i thought it was... it's kind of amusing that horse meat causes a stir while cow meat doesn't it's all just a matter of what's normalized i guess.

[richardhod]

Agreed. Yet there is a case: I think the use case is for those who would rather do without centralised government and rather have a libertarian polity.

[Tomte]

And you need to trust each and every one of these people not to lie.

That's the key issue: Bitcoin works, because Bitcoins are "born" on the blockchain.

Anytime you need to relate real-world concepts to the blockchain, you need trust again. As you said: "if you trust the veterinary".

[melkiaur]

No, I think you "only" need to trust the veterinary, and make sure that all animals are tracked (which is the case in Europe, which is why the Lasagna scandal came to be a scandal). Both things are already true here.

The anti-double-spend features of blockchains is what matters after that: your cow cannot be sent to slaughterhouse 1 and 2 at the same time. Slaugher house cannot ship it to butcher A and butcher B. And it's fairly easy to check that the butcher doesn't sell it twice.

Though as I said in another comment, this can all be solved very easily if you give the DB hosting to the veterinary authorities, and very likely to be much cheaper too.

[ajkjk]

None of those seem to require a blockchain at all; a trusted authority database would accomplish the same thing at a fraction of the cost and complexity.

[h1d]

The point is you don't need a central authority. And I'm sure running a central authority costs some too which could also gain power that no one in the industry can resist.

[ajkjk]

Yes, that's the point: pay lots of money and make your system incredibly complicated, in exchange for not having a central authority when you literally already have one you could just use, for a worse and less-maintainable version of the same technical result.

[danielmg]

but in most countries there is a central authority in the shape of a government agency responsible for agriculture.