This is a another new article in a mini-series that started with ‘Old-School’ Merkle Trees Rock, Merkle Trees In Pictures and Blockchains in pictures.

Say you were going to make an app or service, and colleagues are yelling “blockchain”. You should consider non-blockchain solutions too. You should also consider vanilla Merkle tree solutions. In my opinion, they are underrated and should be chosen more often. A table that might help:

Criteria Vanilla Merkle tree Blockchain
Nature? Tree-like adds, changes, and deletes (but moves are deletes and adds); everything is mutable Chain-like notwithstanding an append-only restriction; nodes are immutable; with a merkle-tree as underlying an implementation aspect it is really part tree-like and part chain like
Node from which you can navigate to all other nodes? The root. Address remains constant The end of the chain. Location moves
Growth? Suits a limited number of records, a percentage of which would change in a given period Suits an ever increasing number of records, including acceleration of that over time
De/centralized? Centralized - at least the root node is Decentralized - consensus based authority featuring “proof of stake” and “proof of work”
History? The subscriber can miss some changes to the tree, only “current” is purported to be available Retained, notwithstanding forks, pruning, and lost transactions
Scope? Most likely to be single purpose (say ‘2016 election results by voting district’) Can be general purpose (e.g. Etherium). Specific purpose ones more likely though
Subscribable? Is the appeal of this, including partial-tree subscriptions Possible, logistically hard in the case of the biggest implementations, and ultimately unlikely by a non-government entity
Public/Private? Either Either, but ‘private-ish in public’ is regular too
Tamper evidence? Yes Yes
Tamper proof? Tampering by centralized entity possible (or their delegates). Only insofar as incorrect records could be appended, but that should be verifiable
Truthfulness of underlying payload data? Tech does not speak to data’s accuracy, only to its authenticity Tech does not speak to data’s accuracy, but via its “consensus” aspects makes a strong assertion about authenticity
Cost of initial implementation? $ $$ - $$$
Worst case scenario? Rate of change too high for subscribers to keep up Dyson Sphere (Nat Pryce quote - see below)

Nat Pryce’s Fermi Paradox / blockchain theory:

“Crypto-currencies are the reason for the Fermi Paradox. Alien civilisations discover crypto-currencies, start depending on them, require ever increasing amounts of energy to run their economy, eventually surround their star with a Dyson sphere to capture all the energy their economy needs, and effectively disappear from the universe.”

Thanks also to Prasanna Pendse for tweaks and fixes to the table above.