[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?