The US Securities and Exchange Commission approved spot Bitcoin ETFs at block 826,565. By block 840,000, those funds held more than 800,000 BTC. By block 925,421, U.S. spot ETFs collectively held **≈5–6%** of circulating BTC (per live trackers at the time).
Only after reading does the translation arrive: those blocks correspond to January 2024, April 2024, and Nov. 27, 2025. The story makes sense without months or years, what matters is the sequence.
Bitcoin already uses two notions of time. Developer documentation describes the chain as an ordered ledger in which each block references the previous one, with the difficulty recalculated every 2016 blocks to aim for roughly 10 minutes per block.
Halvings and upgrades key to specific heights, not wall-clock dates, because height is exact, while the calendar date is an estimate that depends on hashrate. Civil time uses dates and hours. Bitcoin uses a strictly increasing height for order, while wall-clock timestamps can drift within consensus bounds, and short reorgs can relabel the exact “when.”
Bitcoiner and software engineer Der Gigi frames Bitcoin units as “stored time” and the network itself as a “decentralized clock.” Satoshi’s pre-release code called the ledger “timechain,” treating it as a system that orders events over time rather than simply storing data.
Developers schedule forks by height because it maps roughly to future calendar dates. The mapping isn’t exact: it depends on future hashrate and only re-targets every 2,016 blocks, so the calendar date can drift before difficulty adjusts.
The ETF story told in six-digit numbers reveals why marking history by height is more than a meme: it’s a bet on whose clock the internet will trust.
Time as power: who runs the clocks runs the networks
Before 1960, time signals were based on Earth’s rotation and on national observatories. Major nations then jointly developed Coordinated Universal Time, which was formalized in the 1960s as the global reference time. UTC is a political and technical compromise, International Atomic Time plus politically managed leap seconds (which standards bodies have voted to phase out by or before 2035).
Control over the standard means control over the coordination layer underpinning finance, aviation, and communications.
David Mills’ Network Time Protocol, first specified in 1985, gave networked machines a shared notion of UTC within milliseconds. NTP became a self-organizing hierarchy of time servers keeping the internet synchronized.
Whoever runs the clocks runs the networks. Governments and standards bodies have held that privilege since the telegraph era.
Satoshi sidestepped that hierarchy entirely. The Bitcoin whitepaper describes a “peer-to-peer distributed timestamp server to generate computational proof of the chronological order of transactions.”
In Satoshi’s code, the ledger was named “timechain,” which is evidence that ordering events, not just transferring money, was the core design goal.
Leslie Lamport’s 1978 paper showed that in distributed systems, you care first about the consistent ordering of events, not matching wall clocks. Bitcoin is Lamport clocks with a burn rate: proof-of-work enforces total order and an approximate tempo, replacing trusted time servers with energy expenditure and consensus rules.
What block time really is: probabilistic intervals, not a wall clock
Bitcoin’s block arrivals follow a Poisson process. Block time averages ten minutes while actual intervals follow an exponential distribution around that mean.
Block timestamps, by contrast, are deliberately fuzzy. Bitcoiner and software engineer Pieter Wuille points out the header’s time field should be treated as “within a precision of hours.”
This is “inaccuracy by design”: Bitcoin only needs timestamps accurate to within an hour or two for difficulty and anti-reorg rules.
What “network-adjusted time” actually is
- It’s a peer median: each node computes the median of its peers’ reported times to adjust its own clock’s idea of “now.”
- Not NTP: this is internal to Bitcoin’s p2p network; it doesn’t require or assume external time servers.
- Validity window: a block header’s timestamp is accepted if it’s greater than the median of the previous 11 blocks and not more than about two hours ahead of the node’s network-adjusted time.
- Implication: timestamps are intentionally coarse (think hours, not minutes); height enforces strict ordering. Bitcoin Core considers a timestamp valid if it exceeds the median of the previous 11 blocks and falls within the network-adjusted time plus 2 hours.
For those who care about human time, timestamps are squishy. For those who care about ordering, block height is perfect. Wall-clock precision is deliberately relaxed, as what must be precise is the sequence enforced by proof-of-work and height.
Historiography in blocks: when the chain becomes the canonical “when”
Bitcoin culture already treats block height as canonical. BIP-113 switched locktime semantics to the median time of prior blocks so that the chain itself defines forward progress.
If you want to know when an event “really” happened in Bitcoin’s logic, you look at its position in the chain.
Timestamping literature treats blockchains as neutral, append-only time anchors. Work on blockchain-based timestamping proposes committing event hashes to public chains to prove “by block X, this document existed.”
That’s already a primitive version of historians citing block height.
Art and media theory are playing with this, too. Matt Kane’s “Gazers” syncs its internal calendar to lunar cycles and on-chain triggers. Web3 archival projects frame themselves as “documents in time on the blockchain,” treating chain state as the authoritative “when.”
A 2023 economics paper argues “timechain” may be more apt than “blockchain,” positioning the ledger as a temporal ordering system. This isn’t just a meme; economists are adopting the frame.
The friction: human rituals meet probabilistic blocks
Loose timestamp rules mean block times can go “backwards” a bit. Consensus only requires timestamps to be monotone in median-of-11, not strictly increasing. That’s fine for security, but it’s messy for historians wanting sub-hour accuracy.
Short reorgs can temporarily re-label “when” something happened. Protocol researchers title papers “in Bitcoin, time doesn’t always go forward.”
There’s also a social gap. Humans live on weeks, months, and ritual calendars. UTC exists to map those rhythms onto clocks. Bitcoin’s ten-minute heartbeat ignores weekends and holidays, a virtue of a neutral system, but “block 1,234,567” feels alien compared with “Jan. 3, 2029.”
Security note: Bitcoin historically tolerated a “time-warp” quirk where miners could collude on skewed timestamps to slow difficulty increases. It’s constrained in practice and the ecosystem has long discussed consensus cleanups to fully close it, useful context when arguing Bitcoin as a clock.
Beyond Bitcoin: Lindy effects and Schelling points
A Markets essay says, “If Bitcoin is a clock written by God, then Ethereum is a plant,” using the metaphor to describe BTC’s fixed-supply, hard-coded schedule. Because Bitcoin is the oldest, most secure proof-of-work chain with the most accumulated energy, it’s uniquely suited as a neutral time reference.
Academic reviews note that security and longevity matter: a “clock” no one expects to survive the century is a poor anchor for archives.
Bitcoin’s Lindy effect and mining economics make it the Schelling choice for “internet time,” even if other chains have faster blocks. Ethereum’s flexible protocol makes it feel more like a programmable environment than a metronome.
Android “timechain” widgets display block height on home screens. Physical Bitcoin calendars exist. Most explorers display both the block height and a human timestamp, but lead with the human timestamp. Flipping that default would signal normalization.
UTC took years of negotiation before becoming universal. In crypto, BIPs encode policy decisions about interpreting time and have become de facto standards.
It’s not a stretch to imagine a style guide: “When citing an on-chain event, include block height; date optional.”
Crypto-focused publications routinely say “at block 840,000” when describing halvings, training readers to treat height as a first-class temporal reference. Web3 archives hint at a future where museum labels show both “Block 1,234,567” and “Oct. 5, 2032.”
Example citation pattern: bitcoin-mainnet #840,000 (hash: 00000000…83a5) — 2024-04-20 UTC (halving).
This makes the reference unambiguous and machine-verifiable across forks and test networks.
Papers argue that hashes anchored to public chains can prove a document existed no later than a given block.
Courts could formally recognize such anchors for evidence. Git already uses hashes to define “when” a change happened; the wall clock is secondary.
Bitcoin doesn’t have to replace UTC. The defensible line is that Bitcoin has become a parallel time axis for digital history: provable, neutral, ordered by energy and consensus rather than states.
The question is how far that axis bleeds into law, archives, and collective memory.
2040: a world where height comes first
The historian pulls up the archive entry. “First spot ETF approval: block 826,565 (Jan. 10, 2024).” The date sits in parentheses, a footnote to the canonical reference.
Her editor flags it: “Do we need the calendar dates?” She deletes them. Readers who care can translate.
Outside, the wall clock shows 3:47 p.m. The timechain widget shows block 2,100,003. Both are correct. One measures Earth’s spin and political compromise. The other measures accumulated proof-of-work since genesis.
For her dissertation on Bitcoin’s institutionalization, the second clock matters. It’s the clock that can’t be edited, the clock that doesn’t observe daylight saving, the clock whose ticks you can verify back to block zero.
It’s not the only clock. But for a growing class of events, it’s the clock that counts.
