3 ms·

"Miners participate in Bitcoin's distributed transaction-clearing process, competing for the free bitcoins that are awarded at random to one miner every 10 minu

by omni 14y ago

"Miners participate in Bitcoin's distributed transaction-clearing process, competing for the free bitcoins that are awarded at random to one miner every 10 minutes." Is this even remotely true? I thought they were all basically trying to brute force a valid hash, with no time-based guarantees at all.

nullc 14y ago
The definition of 'valid' is adapted by the system so that on a long term average the rate of new solutions is one per ten minutes. (The mental model of 'brute force a valid hash' is often unhelpful. Most people think of "given Y find a specific X such that H(X)=Y", Bitcoin is more like "Given P,B,T find any X,Y such that H(Time||P||H(B||X)||Y)<T")
discountgenius 14y ago
The "diffuculty" of solving the hash is automatically adjusted by the network so that, on average, 6 blocks are discovered every hour. edited for clarity.
- omni 14y ago
  Thanks for the clarification, I thought the hash difficulty was updated much less frequently. The word "random" is still very misleading, as your chances would still be determined by your mining power.
  - donpdonp 14y ago
    My answer was slightly misleading, while blocks are won about every ten minutes, the difficulty is adjusted every 2016 blocks (2016 * 10 minutes = 14 days). https://en.bitcoin.it/wiki/Difficulty https://en.bitcoin.it/wiki/Difficulty
  - sp332 14y ago
    The word "random" is still very misleading, as your chances would still be determined by your mining power. The winning hash is random with uniform probability. So the more hashes you have, the more likely it is that you have the winning hash.
sp332 14y ago
The network modifies the difficulty of finding a block, to keep the average time close to 10 minutes. Right now it's 2,190,866 times as hard as when the network launched. eta: Each block is based on the "winner" of the previous block. So you can't skip ahead, because you can't know the "winner" of the current block. https://en.bitcoin.it/wiki/Block_chain https://en.bitcoin.it/wiki/Block_chain
donpdonp 14y ago
Its true and actually the best concise summary of bitcoin mining I have read. All miners are in a race to find the valid hash for the block they are working on. The first miner to find the hash wins the block and gets 50 coins. The system as a whole notes how long its taking miners to find the hash and adjusts the difficulty of the winning hash based on this speed. So in actually blocks are won in a little less or a little more than 10 minutes and the system adjust to keep the time as close as possible to 10 minutes.
- nullc 14y ago
  Er. Describing it as a race inspires some of the most common misconceptions about mining. If it were a race and Alice ran 10x faster than Bob, Bob would probably never win. Bitcoin mining is stochastic, and for a given current difficult each calculation performed by anyone has an equal very small probability of being a solution. Like throwing dice and trying to get a 1. If Alice mines 10x faster than Bob then Alice will find, on average, 10x more solutions.

by omni 14y ago

nullc 14y ago

The definition of 'valid' is adapted by the system so that on a long term average the rate of new solutions is one per ten minutes. (The mental model of 'brute force a valid hash' is often unhelpful. Most people think of "given Y find a specific X such that H(X)=Y", Bitcoin is more like "Given P,B,T find any X,Y such that H(Time||P||H(B||X)||Y)<T")

discountgenius 14y ago

The "diffuculty" of solving the hash is automatically adjusted by the network so that, on average, 6 blocks are discovered every hour. edited for clarity.

omni 14y ago
Thanks for the clarification, I thought the hash difficulty was updated much less frequently. The word "random" is still very misleading, as your chances would still be determined by your mining power.
- donpdonp 14y ago
  My answer was slightly misleading, while blocks are won about every ten minutes, the difficulty is adjusted every 2016 blocks (2016 * 10 minutes = 14 days). https://en.bitcoin.it/wiki/Difficulty https://en.bitcoin.it/wiki/Difficulty
- sp332 14y ago
  The word "random" is still very misleading, as your chances would still be determined by your mining power. The winning hash is random with uniform probability. So the more hashes you have, the more likely it is that you have the winning hash.

sp332 14y ago

The network modifies the difficulty of finding a block, to keep the average time close to 10 minutes. Right now it's 2,190,866 times as hard as when the network launched. eta: Each block is based on the "winner" of the previous block. So you can't skip ahead, because you can't know the "winner" of the current block. https://en.bitcoin.it/wiki/Block_chain https://en.bitcoin.it/wiki/Block_chain

donpdonp 14y ago

Its true and actually the best concise summary of bitcoin mining I have read. All miners are in a race to find the valid hash for the block they are working on. The first miner to find the hash wins the block and gets 50 coins. The system as a whole notes how long its taking miners to find the hash and adjusts the difficulty of the winning hash based on this speed. So in actually blocks are won in a little less or a little more than 10 minutes and the system adjust to keep the time as close as possible to 10 minutes.

nullc 14y ago
Er. Describing it as a race inspires some of the most common misconceptions about mining. If it were a race and Alice ran 10x faster than Bob, Bob would probably never win. Bitcoin mining is stochastic, and for a given current difficult each calculation performed by anyone has an equal very small probability of being a solution. Like throwing dice and trying to get a 1. If Alice mines 10x faster than Bob then Alice will find, on average, 10x more solutions.