In his 1934 book entited Logik der Forschung,
Karl Popper argued for
falsifiability over verifiability.

Verifying the claim "All swans are white" would require assessment of all swans,
which is not possible, the single observation of a black swan is sufficient to falsify it.
Citation — Falsifiability

This means the typical number of steps between two randomly chosen nodes grows
proportionally to the logarithm of the number of nodes in the network. The simplicity
of this approach makes it a nice starting point for decentralized search.

"It is possible to prove that in the model of a d-dimensional lattice with uniformly
random shortcuts, no decentralized algorithm can find short paths [...]. Exploring
further, though, we find that a subtle variant of the Watts-Strogatz network
will in fact support efficient search: Rather than adding the long-range shortcuts
uniformly at random, we add links between nodes of this network with a probability that
decays like the dth power of their distance (in d dimensions)."
Jon Kleinberg — The Small-World Phenomenon and Decentralized Search

It has no moving parts. It's just a list of items. And each item has
some properties. The defining characteristics though, are that each
item has 1. a property that acts like a finger print, and 2. a property
that points to the item that came before it. A secure
hash
function creates the finger print using the item's properties as input.
A correct and complete blockchain can be implemented in fewer than 50 lines
of code.

A blockchain is most likely the least interesting part of any system that
is built with one. Networking, consensus and replication,
for example, are discrete and non-trivial problem domains that can form a
foundation for maing a blockchain useful.