[300bps]

The word immutable has a meaning.

Blockchain does not fit that meaning.

Immutable doesn’t mean, “as long as 51% of miners want it to not change”.

Immutable doesn’t mean, “doesn’t change unless we get hacked and then we’ll change it”.

I could give more examples. Blockchains are not immutable.

[brian_cloutier]

Blockchains are not immutable because nothing made of matter is immutable.

If you wanted something to be immutably published you probably want to get it into a major print newspaper; it would be extremely difficult to find and destroy every single copy of the WSJ for 2022-01-28.

Even that is not immutable though, finding and destroying every single copy is possible. Hopefully you agree that it is nice to have the word "immutable". And maybe you agree that most of the times you have called something "immutable" what you have really meant is that mutating it would be extremely expensive.

Historic bitcoin blocks are mutable, but mutating them is very expensive and also has never happened, this seems like a good use-case for the word "immutable".

[300bps]

You seem to be assuming that I am making the mistake of robotically defining the word "immutable" to some impossible level of unchanging.

I assure you I am not. I am simply pointing out the ridiculousness of someone stating that blockchains are immutable when they are changeable and have changed.

In contrast, your example of snatching up every copy of a major print newspaper for a single day has never happened and will never happen.

But blockchains have changed and once regulators and courts get involved, you'll see just how malleable they are.

[brian_cloutier]

You've been kind enough to make a testable prediction here! Let me make it a little more concrete. Currently Bitcoin block 700000 has the hash 0000000000000000000590fc0f3eba193a278534220b2b37e9849e1a770ca959, I'm very confident that 5 years from now it will have the same hash. What do you think is the chance that history will have been rewritten?

[rschachte]

The statistical likelihood of a 51% attack happening on the blockchain seems statistically way less likely than a hack targeting our existing financial system.

I mean, it's pretty easy why blockchains are considered immutable, you can even code one from scratch in Python in less than 200 lines of code.

To control 51% of all those hashing power, an entity would need to power computers that works as much as that, along with paying for the equipment and energy consumption and whatever costs needed for the operation. Current estimates of Bitcoin mining energy usage stands at 71 TeraWatthour, enough to power the whole country of Austria.

[CamperBob2]

To control 51% of all those hashing power, an entity would need to power computers that works as much as that, along with paying for the equipment and energy consumption and whatever costs needed for the operation. Current estimates of Bitcoin mining energy usage stands at 71 TeraWatthour, enough to power the whole country of Austria.

Or they'd need to find a way to break SHA256. That's a risk you don't hear much about.

[rschachte]

yah, I have actually thought about this. Tbf, I'm not advocating strongly for or against blockchain. I'm just keeping an open mind in the same way when web 1.0 was being developed and researched.

I think it's fairly destructive to just discount new technology based on feeling. It really is a fun technology to learn and the more minds like we see on HN that research the topic, the more likelihood we will have in expanding the usefulness and security of blockchain use-cases.

[runarberg]

No, but you can discount the technology based on it’s historical records compared to it’s promises. Web 1.0 promised to be a good system of exchanging documents which could refer to each other. It delivered that pretty nicely and later improved on it.

Bitcoin promised to be a decentralized alternative to fiat currency and failed when it couldn’t scale to be even a tiny fraction of the global transaction. When people tried to improve on the original proposal they also failed at the very same thing while inventing new problems in the mean time. As of yet the only realized potentials of the technology are scams (which were never promised—at least to my knowledge).

Compared to Web 1.0 I think it is pretty safe for you to discount the technology based on a history of scams and failure to realize promised potentials.

[Eddy_Viscosity2]

The OP's point was that 51% of miners could agree to a change, and in a system where there are very large players that might not involve that many people.

[philistine]

And it already happened a bunch of times. Bitcoin has been forked a bunch of times, and one could argue the fork that gave birth to Bitcoin Cash was a successful 51% attack on Bitcoin itself.

[philistine]

Let's say the world's banking is running on blockchain. The US Congress is basically a veto on world banking, and I don't see how blockchain technologies can change any of that. The US Congress can pass a law saying any US bank and anyone transacting with them must use a specific version of the blockchain code, decided by the Department of Commerce.

If it's illegal to transact with the US under a previous version of this hypothetical blockchain banking technology, that's your 51% right there.

How could blockchain allow legal banking institutions to refuse to follow the law?

[300bps]

It isn’t as expensive as you think to 51% attack various coins.

https://www.crypto51.app/

You only mentioned BTC but that’s just one coin. Several alt coins (with multi billion market caps) have had 51% attacks including ETC and BSV.

But anyway the original point was that it is literally wrong to say that blockchains are immutable. You didn’t address that point at all, so I guess you agree with it?

[mattwilsonn888]

If 51% of miners could change anything everyone would be spinning up Alpine Virtual Machines with minuscule hash power. You fundamentally misunderstand how blockchain works.

Your "we" in the second example is the majority of network users - any network where that isn't true is not decentralized.

You do not know what you are talking about. The fact that grifters often don't know what they are talking about and use that to whip up positive spin on blockchain tech does not give you any good excuse to do the opposite - you are both morons.

[boopboopbadoop]

> Your "we" in the second example is the majority of network users - any network where that isn't true is not decentralized.

So... you’re saying it’s mutable.

[philistine]

You both are talking from the unsaid point of view that an immutable public ledger is a good thing. The reality of our world disagrees with your unsaid compact.

Nothing needs an immutable public ledger. Any fraud due to shipping, or banking, or taxes, is a problem of inaccurate entry of data into a ledger, not nefarious changes to what already exists.

[brian_cloutier]

Immutable ledgers are a godsend and are useful in many different contexts:

- https://en.wikipedia.org/wiki/Certificate_Transparency

- https://en.wikipedia.org/wiki/Lab_notebook

- https://www.newamerica.org/digital-impact-governance-initiat...

Adjustments needed for shipping, banking, or taxes are trivially accommodated; those are additional events which can be appended to the log.

[philistine]

None of your examples are all, at the same time, immutable, public, or ledgers. The Georgian land thingie is the most interesting, but a Georgian judge could definitely order a change in ownership due to incorrect data entered into the ledger, so it's not immutable.

[brian_cloutier]

> a Georgian judge could definitely order a change in ownership due to incorrect data entered into the ledger, so it's not immutable.

There seems to be a misunderstanding. The ledger is immutable. That doesn't mean the state is immutable! Immutable state is not very useful. A judge could absolutely order that the ownership of some parcel is changed, but the change will appear as a separate record and everybody will be able to see the change and nobody can credibly deny that the change happened, not even the judge.