Slush Pool: Sharing the Wait for a Bitcoin Block
In 2010, a small miner could work for weeks without finding a block. Slush proposed joining forces. The resulting pool changed how miners shared uncertainty—and how they proved they had done the work.
3-Minute Fast Briefing
- The ParadoxSlush proposed cooperative mining on November 27, 2010; Braiins later dated the pool’s operational launch to December 16.
- The Turning PointPooling divides rewards among contributors and reduces individual payout variance; it does not make the same hashing power inherently more productive.
- The LegacyA share is evidence of work at an easier target. It is not a fragment of a finished block, and it does not remove the need to trust the pool’s accounting.
Chronological Timeline
Slush opens a forum discussion; participants examine payout variance and ways to verify contributions.
Braiins identifies this date as the launch in its later account of mining-pool history.
Three CPUs, No Block
On November 27, 2010, the forum user Slush described a familiar kind of discouragement: he had been mining with three CPUs for weeks and had not found a block. GPU mining was making the gap between small and powerful machines harder to ignore. His proposal was to put small miners into a cooperative pool, find blocks together and divide the proceeds.[1]
Another participant, ribuck, corrected a premise in the proposal. At a fixed difficulty, combining two computers does not magically improve what their total hashing power can earn. Slush’s reply sharpened the practical problem: people might stop contributing if the first payment seemed impossibly far away. A smaller reward arriving more often could keep them involved.[1][2]
The Reward Was Large; the Wait Was Uneven
Bitcoin’s block subsidy was then 50 BTC. A solo miner could receive that subsidy on finding a valid block, yet a small machine might go a long time without one. A pool combined the work of many machines and shared the rewards. Each participant traded the chance of keeping a whole reward for smaller portions of the pool’s successes.[2]
This is a change in variance: how widely actual results swing around an average. With the same effective hashing power and ignoring fees, joining a pool does not by itself increase expected rewards. It changes their distribution over time. Even a pool can have a long unlucky stretch, and payout timing also depends on its rules; cooperation is not a guarantee of daily income.[2][3]
How to Count Work That Did Not Win
A pool cannot pay merely because a computer claims to have been busy. It asks for results that meet an easier target than Bitcoin requires for a block. These submissions are called shares. The pool can check them cheaply, and their frequency, weighted by difficulty, provides statistical evidence of the work supplied. Most shares do not qualify as Bitcoin blocks. Occasionally one also meets the network’s harder requirement.[2][3]
A share is therefore not a little piece that gets glued to other pieces until a block is complete. It is a verifiable result from the same search. The early discussion also addressed whether a miner could keep a winning result: the work commits to a block whose reward pays the pool. Replacing that payment changes the block being hashed; the old successful hash cannot simply be reused.[1][2]
A Shared Wait, a New Responsibility
The November forum post was a proposal. In its later history, Braiins identifies December 16, 2010 as the pool’s launch date. Keeping those milestones separate avoids turning the opening discussion into an already running service. The operation became known as Slush Pool, and later as Braiins Pool; subsequent reward systems evolved beyond the early proportional-sharing idea.[1][4][5]
Slush had acknowledged the central trade-off at the start: participants would have to trust him to distribute the reward. Shares made contributed work measurable, but they did not make the operator disappear. The lasting idea was to make participation less dependent on one small miner’s luck. Its companion question was who kept the accounts and paid everyone their share.[1][2][4]
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