At first glance, black holes and cryptocurrencies seem to belong to completely different universes. One lives in the world of gravity, spacetime, and the edge of modern physics. The other lives in computer networks, digital money, and distributed trust. But in Black holes and cryptocurrencies, physicist Alexey Milekhin argues that the two may share a surprisingly deep idea: in both cases, what we call “time” may not be as fundamental as it looks. The paper starts from a famous idea in black hole physics known as “complexity equals volume.” Very loosely, this is the suggestion that the interior of a black hole keeps growing in a way that mirrors the growing complexity of the quantum state that describes it. Milekhin then pushes that intuition outward and asks a bolder question: could time itself be tied to complexity? Instead of treating time as a pre-existing background clock, maybe some systems build their own sense of time as their internal structure becomes harder and harder to reproduce.
That is where blockchain enters the story. In an ordinary explanation of Bitcoin-like systems, we say miners add blocks, the chain grows, and the network follows the longest valid branch. The paper invites us to read that process in a different way. A blockchain is not only storing transactions. It is also creating an agreed ordering of events for many different observers who may not trust one another and may not even receive messages in the same order. In that sense, the blockchain is doing something very close to building a shared timeline.
This is why the paper is interesting even for readers who do not care much about black holes. It takes a familiar blockchain fact and turns it into a philosophical point. In a decentralized network, there is no single master clock that everyone must obey. Nodes can be out of sync, messages can arrive late, and competing versions of history can briefly coexist. Yet the protocol still settles on one dominant history. The author’s claim is that what users call “the current time” in such a system is really the position along the most computationally developed chain. In simpler words, blockchain time is something the network produces, rather than something it merely reads from the outside world.
The analogy becomes more vivid when the paper talks about changing the past. In blockchain language, rewriting history is hard because you would have to rebuild old blocks and then catch up with the honest chain while everyone else keeps extending it. In the black-hole analogy, that resembles trying to cross a region whose effective distance keeps growing too fast. The comparison is not meant to say that Bitcoin literally contains tiny black holes, of course. The point is that both systems seem to make “going backward” difficult for structural reasons. Perhaps the mere concept of time in physics and why we can’t go back holds an answer in these concepts.
Another nice part of the essay is the way it reframes consensus. Blockchain folks often describe consensus as agreement on the valid ledger. Here it is described more like agreement on a common history of events. Forks, orphan blocks, and temporary disagreements become less like software bugs and more like fluctuations in a system that still manages to recover a stable large-scale order. That makes the protocol sound less like a bookkeeping trick and more like a machine for creating a shared past.
The paper is also careful about what it is and is not claiming. This is not a proposal for a new cryptocurrency, and it is not a proof that spacetime literally comes from blockchain. It is a conceptual essay, written for the Gravity Research Foundation essay competition, using classical proof-of-work blockchains as an example of how “complexity equals time” might already appear in a real system. The author even points out an important difference: blockchain complexity is classical and easy to observe, while quantum complexity in gravity is a much stranger and more subtle object. The article is worth reading since it gives blockchain a new kind of dignity, presenting it as a rare working example of many agents manufacturing a notion of temporal order out of computation. Even if the analogy never becomes more than that, it is a beautiful one. It suggests that blockchains may be interesting not only because they move money without a bank, but because they offer a small, tangible model of how order, history, and perhaps even time can emerge from rules, messages, and growing complexity.
