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Comment by udfalkso | Hacker News Reader

Let's say half the miners stop mining. This would make it twice as likely that the remaining miners will mine each new block, right? If so, then this acts a bit like a price doubling from their perspective which would counteract the disincentives you mention. Perhaps a new equilibrium will emerge that's not quite so extreme because of this effect.

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> This would make it twice as likely that the remaining miners will mine each new block, right?

Not immediately. The "difficulty" of each block adjusts every 2016 blocks, the algorithm takes the average time between blocks and changes the difficulty accordingly so that the expected time becomes 10 minutes.

If half the miners stop mining, it will take around a month to mine 2016 blocks to trigger the difficulty adjustment, and that's if none of those miners stop mining before the adjustment happens. If the price keeps dropping and miners keep stopping, it could be 2 or 3 months before the adjustment happens

Yes, but even if the block time is longer, the probability that I will "win" the block goes up. Someone has to mine the block and if half of the competition goes away my chances go up. This incentive will counter the temptation to stop mining, dampening the effect you mention.

Miners don't compete directly to "win" blocks. If everyone except a single miner stopped mining right now, that last miner would mine 100% of the blocks. However, they'd still make exactly the same amount of bitcoins as if everyone else was still mining - until the next difficulty adjustment

Is there a good reason for the difficulty adjustment period being 2016 blocks? What would be the consequences of reducing this number?

I'm not sure what the reasoning is, but to be honest I don't think it's a good system. Block time averages have been about 9m30 since bitcoin's inception, so it's clearly not good enough to properly target 10min/block

When bitcoin cash forked they changed the period to 144 blocks (along with some other changes i believe?), so they have a much smoother difficulty graph.

I see. Thanks

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