How is this being solved by a block-chain?

You still need to trust all the people in the production line (Farmer, Juicer, Seller and not to mention that transportation guys) that brought the bottle of juice to market to actually record things correctly into the used block-chain.

The trust required in the data entry "Link/Step" basically results in the use of a block-chain to be pointless, as trust is already a requirement in this particular chain of custody.

This is also why the block-chain only really works in Digital Only assets, as you link the asset it self in the block-chain itself.

You're right, but that isn't the problem being solved. That problem would be present in a centralized solution as well.

This solution allows the same benefit of having a MONOPOLIZED SOLUTION for tracking supply chain, without the negatives of Monopoly taking monopoly profits.

Do you get it now?

There are various projects developing solutions for hardware and sensor integration

The blockchain makes it extraordinarily difficult to tamper with post facto. As the ledger is distributed with multiple parties and each block is hashed, it’s exponentially difficult to change later. This means that no centralized entity can cook the books if a situation arises.

But that's the point blockchain is missing. You don't need to tamper with the data in the ledger because there is no way to put a carrot in it, how would you prove that the carrot in the juice is the same carrot picked? Technology isn't going to solve for that without some magical way to identity specific carrots (or beef, or whatever) that have been transformed into something else... or even just from another carrot in the next box. Blockchain is interesting but trust is still required in the system, and in many cases it is in fact blind trust.

What? For this system to be truely trustless, the blockchain needs to be owned and maintained by all the people who use it. That means farmer, carrot juice guy, distributor, and retailer need to all have beefy computers with large hard drives to hold the entire blockchain and keep mining it.

Sure, it's great that you don't have to trust Amazon or Wal-Mart to trace the links back, but you could do just as well way more cheaply with a well-maintained independent 3rd-party with an AJAX API on top of a Postgres database. (Well, except for the part where said 3rd-party gets bought out by Twitter...)

>For this system to be truely trustless, the blockchain needs to be owned and maintained by all the people who use it. That means farmer, carrot juice guy, distributor, and retailer need to all have beefy computers with large hard drives to hold the entire blockchain and keep mining it.

Trustless isn't a well defined term so it is hard to disagree directly with what you are saying. However I would argue that most relying parties do not need to have the full state of the system to ensure they aren't cheated. In that they don't need information about other assets to track the assets they care about. For instance the carrot juice guy only needs to validate the chain of custody of the carrots. You could put a merkle proof for each custody change on a QR code on the side of the carrot box. The block headers are 70MB, the chain of custody is probably less than 10KB.

>Sure, it's great that you don't have to trust Amazon or Wal-Mart to trace the links back, but you could do just as well way more cheaply with a well-maintained independent 3rd-party with an AJAX API on top of a Postgres database.

I agree that a running PoW blockchain may be overkill for supply chain tracking. However a BFT distributed database maintained by several trustworthy institutions is probably better a Postgres database. Often blockchain is used as shorthand for "BFT distributed database maintained by several trustworthy institutions".

This is solvable without blockchain though. Supply chain tracking already happens at the moment without Blockchain.

Indeed. And more to the point blockchain doesn't do a damm thing to improve trust. If someone in step three tosses the carrots out the window and uses a different batch the blockchain isn't going to get that information.

The blockchain in this example doesn't add or reduce trust at all it's just a time stamped database of stuff people said. We have those already.

Bingo. I still don’t follow how blockchain solves current problems. If the problem in your country is a lack of good record keeping, that’s not a technological problem. It’s a political problem. Cheap solutions have existed for centuries. The real question is why haven’t they been adopted? Why would those in power allow blockchain to be adopted but not existing technologies?

In most cases it seems that the existing technologies have been adopted and the people advocating for blockchain-based solutions just aren't aware that it's a solved problem.

I completely agree. It's naiveté. Technically, my local county recorder's office is a blockchain that has existed for centuries. It's cheap, reliable, correctable, enforceable, etc. It has all of the features without the downside.

People lying has always been a problem with grand internet visions. Remember the semantic web? It never went anywhere because people lie in metadata. There would have to be some sort of reputation system for participants, but with that comes an independent adjudication system to determine who is telling the truth. This brings back centralization.

I was talking with some people I know who work on HyperLedger, which is really lightweight blockchain stuff connected to the Linux foundation, and they say the most used blockchain is the one used for tracking where diamonds came from. I guess they are unique enough, or identifiable enough that they can't be easily replaced by diamonds that came from outside the system.

The blockchain solves the problem of trust. Without the blockchain, you need to trust some monopolistic middle-man that became monopolistic because he was the winner in the 'race of acquiring trust' from its consumers.

With a blockchain to track phisical goods, any third-party can consult or print a new transaction into the blockchain, it we wont need to deposit our faith in a company or a government.

We managed to solve the problem of trust, the best way we could, with the tools we had as a society, but if you analize all the paperwork, the bureocracy, the taxes and time taken to make the same system work in the classical way, there's a clear advantage in the new way od doing things.

Blockchain solves nothing.

How do I indelibly serialize my carrots? What stops me from eating the carrots I said I sent to the juice dude, and then just sending him some carrots I picked up from Loblaws?

In this particular case it doesnt solve this problem.

It solves the problem of the tracker.. Before you needed to trust the middleman by using another authority for trust, like your government given permissions and making inspections.

With the blockchain you can transfer that to the peers participating in the activities themselves.

It's the descentralization of trust. Right now we have to trust several databases from different peers, that no one have access to, and make a big effort if we need for instance know the state of something tracked by those systems.

Blockchain is a hype in a lot of situations, but that doesnt mean it doesnt have some problem domains it can be used to solve..

For me is just a algorithmic tool, like a hash, binary tree or a merkle tree. There are some problem domains where you might consider it as something to be used to solve some particular sort of problems.

Maybe for tracking physical goods it might not even be the best tool, according to the circustances, but it is something to be take into consideration, to solve this particular problem domain.

> With the blockchain you can transfer that to the peers participating in the activities themselves.

Assuming you can trust them, which kind of defeats the point. If you trust your supply chain, why do you need a computationally expensive trustless system?

Honestly the bigger problem is that it DESTROYS value for middle men so badly that there are a ton of reasons not to do it. In any consumer product that sells a story or a history the idea of checking ones work has only potential destroy value.