I conjecture that blockchain only solves peer-to-Peter digital currency, I.e Bitcoin. I conjecture it has no business solution about supply chains or tracking bananas or weed or porn any other nonsense. Almost invariably, a central authority actually exists and is hidden behind buzzwords, or its a bad version of Git.

Look into Saito. Universal broadcast PKI networks are useful for more than just money.

"look into it" how?

Not that I approve this usage, but why not weed?

Explain to me why you need a blockchain for anything to do with weed (and not bananas)?

Decentralised marketplace, maybe? Open-source, trustless. So people can't scam you. Not saying that blockchain is a good way to do this: For instance, privacy would be a major red-flag, as well as the question of who's going to do the mining.

[edit]

Just found this: https://openbazaar.org/ Doesn't appear to use its own blockchain. Does use cryptocurrency though, for largely privacy and anti-censorship reasons. Uses multisig capabilities in Bitcoin to enable escrow/chargeback.

As to why you wouldn't do the same thing for bananas: Weed is illegal, so any business selling weed is in danger of being shut down. Something decentralised is more immune to getting shutdown. Compare Napster (centralised) to BitTorrent (decentralised).

As I said:

> I conjecture that blockchain only solves peer-to-[peer] digital currency

You kinda just described something like Silk Road right?

Good question. You need to compare apples to apples. Are we talking about file storage? payments? DNS? smart contracts?

in each of these, speed might matter, or size of the data, or interoperability, or high availability, or centralization, etc.

in decentralizing money? yes

Things that require a central authority, such as notaries, certificate authorities, central banks, government, insurance, etc.

Blockchains could give more trust on one hand (corrupt authorities are all over the world), and optimization on the other (less people and processes involved).

A quick overview of applications is here: https://www.blockchaintechnologies.com/applications/

The question is indeed if it's disruptive enough to replace the current way of working.

How can a blockchain be more efficient than centralisation? I once worked at a company obsessed with blockchain and asked the business person who never worked on anything technical in his life this same question, and he mumbled something about “cutting out the middle man” that he probably saw in a TED talk or read in Forbes. The irony is of course that a blockchain literally introduces millions of middlemen who all have a copy of the same ledger, and who all must constantly engage in a protocol to agree on the latest state of the ledger. There’s nothing efficient about it.

How much do you pay your notary? How big of a cut do payment processors take?

Email surely isn't central, and it seems to be pretty cheap for consumers. Do you think we should centralize email to make it better?

The cost of using a blockchain at the scale of one of today's big payment processors is still unknown. The current amount of transactions per second in something like Bitcoin is ridiculous compared to Visa or even any big online retailer. Some say that it could scale to that level but it remains to be seen.

Regarding email it's unfortunately a rather bad example. While I personally host my own email server on a dedicated host I seem to be among a rather small minority. Every time this subject comes up on HN people say that they had a lot of trouble setting up their own email server because they kept being flagged as spam by the big hosts like gmail and friends.

Email is clearly undergoing a rather massive centralization around a few big providers offering an ad-sponsored service.

There are also obvious advantages to centralizing email: when you have many users you can de-duplicate content more aggressively, you can catch spam much more effectively etc... Overall it is more efficient, privacy and independence notwithstanding.

There's also an other important difference between email and blockchains: even if you consider email a decentralized service not all nodes (SMTP servers) need to store the full state and history of all emails sent in the entire world. They just pass emails along and only keep those addressed to a user of this particular server. It's similar to other services like IRC or bittorrent for instance.

Full Bitcoin nodes need to store the full state of the blockchain to function. You can optimize it a bit if you're willing to lose some functionality (discard spent outputs for instance) but not everybody can do that or the system fails and that's still a massive amount of data to keep around forever.

Email is (potentially) decentralized but also distributed. Blockchain is decentralized but every node contains the full state of the system. That's a very big difference when it comes to scalability.

What is the transaction fee if I buy a pizza with Visa vs with Bitcoin? Or a round of drinks or a tank of fuel?

There are 0 fee cryptocurrencies.

How will you pay me $0.001? Or $1 million in a few seconds? With the next gen of cryptocurrencies, available today. Zero fees, instant, worldwide.

But you would first need to develop a system where it would be common to send millions of dollars to untrusted parties at high frequency before you would ever use these zero-fee cryptos.

Email is highly centralized. Try sending an email directly from your workstation using SMTP and see how far it gets.

> Blockchains could

This is always a phrase meaning "blockchains don't" - because if they did, the speaker would have listed the production examples.

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