According to the data stored in the blockchain, the genesis block is mined at Jan 03, 2009. The second block is mined at Jan 09, 2009, 6:24:25 AM. Which is 6 days later. At first, it seems rational to me, because at that time, the only one who was running a node was Satoshi, and even if the difficulty was very low, mining by one machine was very time consuming. By this reasoning, I expected the mining of first 2016 blocks would take time at this magnitude (Because after the 2016 blocks the difficulty would be readjusted and set to a lower level, though I'm not sure it can be less than 1 or not). But next blocks are mined very faster.

The difficulty of network was the same for all these blocks. What is the reason for this variation? Was there a jump in the number of miners at that time?


1 Answer 1


The blocks with heights 1-4 may have been mined according to the Poisson process that governs block discovery today and throughout the vast majority of Bitcoin's history. Blocks are mined on average every 10 minutes (with difficulty adjustments every 2 weeks to re-tune) but with variability both above and below. It is certainly plausible that you'd get 4 blocks mined at random times within a 24 minute period. The 6 day gap between the block with height 0 and the block with height 1 is likely explained by Satoshi being the only miner and not having the miner turned on during this time.

Murch states in the comments that Satoshi's original Bitcoin client (main.cpp, lines 2191-2199) would only start mining if it had at least one peer so it is possible that Satoshi's node (and miner) was running when publishing the software but only started mining when a second peer joined the network. Of course today Bitcoin Core (the dominant implementation on the network) doesn't include a miner in its releases.

  • Thanks Michael, so you mean there is not any known justification for that 6 day gap? Apr 24, 2023 at 17:11
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    @AmirrezaRiahi: Without speaking to Satoshi it can't be confirmed 100 percent but the probability of a 6 day gap in a Poisson process at the lowest difficulty level with any hash rate running is infinitesimally small. So almost certainly no hash rate running during that time. Apr 24, 2023 at 19:56
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    I seem to remember that the original Bitcoin client would only start mining if it had at least one peer. So, possibly Satoshi’s node was running when publishing the software, but only when a second peer joined the network both nodes started mining.
    – Murch
    May 1, 2023 at 17:34
  • @Murch: Ha interesting, thanks. Will add to the answer. May 1, 2023 at 17:38
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    github.com/JeremyRubin/satoshis-version/commit/… (you may need to expand main.cpp, because it’s pretty large, see lines 2191–2199)
    – Murch
    May 1, 2023 at 18:41

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