Slush Pool: A Prague Idea Against Mining Lottery

At that time, Bitcoin rewarded the winner of a block with fifty coins. For the network, it was a simple mechanism, but for individuals, it was a tough lottery. The probability of finding a block corresponded to the proportion of their computational power in the entire network. As the total power grew, a small miner could wait longer and longer, even though their machine was working non-stop.

The long-term average might have looked favorable, but electricity bills arrived every month. An individual had to bear a large variance: either they got the entire reward or, after a long period, nothing at all. This pushed people with smaller power out, even though their work would be just as useful for the network as that of a large operation.

Palatinus knew the problem from his own experience. In the forum, he described how a shared server could combine thousands of small attempts and divide the results. A participant would no longer wait for their own rare success; they would get a smaller share every time a block was found by someone in the group.

The mining pool does not change the probability of the entire group or create more Bitcoins. It changes the distribution of risk over time. It's the difference between one lottery ticket with a big win and a regular share of a large bundle of tickets. For a more stable income, the miner pays a fee and depends on the correct accounting of the operator.

Slush did not present his proposal as a purely technical victory. Already in the first thread, he listed the advantages, disadvantages, and necessary trust. The server had to correctly measure the submitted work, not steal rewards, and remain available. The pool eliminated one uncertainty but added an intermediary that the Bitcoin consensus itself did not control.

For a small miner, the biggest problem was not the average return, but time. Statistically, he could have been entitled to a fraction of the reward every day, but the actual protocol did not pay fractions for effort. Either his machine found a valid block and earned a full fifty bitcoins, or it earned nothing. A long streak of failures did not mean the device was not working; it only meant that the lottery had not yet fallen in his favor. A shared server converted this irregular event into smaller shares based on proven work. A pool did not increase the expected number of blocks found, but it changed the rhythm of income, and it was precisely this difference that could determine whether a person could afford to keep mining.

The announcement on November 27, 2010, was not a finished corporate product. Palatinus was looking for people willing to test the protocol, connection, and reward method. The system had to accept partial proofs of work — results too weak for a valid block but sufficient to prove that the miner was actually calculating.

These so-called shares allowed the pool to estimate the contribution of each machine. When a participant found a hash that met the network's difficulty, the pool received the block reward and divided it according to the chosen accounting rule. For the average miner, the result changed from irregular fifty Bitcoins to a stream of smaller payments.

The first version of the service ran under the name Bitcoin.cz Mining Pool. The website, server, and support were largely the work of one person. This gives the Czech primacy a more accurate dimension: it was not a national project or a state program, but a programmer from Prague who solved a specific economic problem of the global network.

The pool also needed to assemble a candidate block and distribute the task to miners. Individual machines provided power, but the operator determined which block header they worked on and what transactions the template contained. The distribution of hardware among many people did not itself guarantee the distribution of decision-making.

Later development of mining protocols, including Stratum V1, aimed to make communication between pools and devices more efficient. The basic trade, however, remained the same: the pool sells a more predictable payout, and the miner entrusts part of the coordination to it. The first server created a pattern that others quickly followed.

Live operation began on December 16, 2010. On the same day, the pool mined block 97,834. The record in the chain today shows the result, but not the tension before it: whether the server would correctly accept the work, recognize a valid block, and assign shares to the people who provided power.

The first block confirmed that coordination works not just in a test. The reward could be divided among participants, most of whom would not have gotten anything on their own at that moment. For small miners, it was tangible proof that their weaker machines did not have to be immediately pushed out of the network's economy.

The date is important to distinguish from the November announcement. The idea, public testing, and live result were three different steps. The story does not begin with the sudden finding of a block but with the weeks before, when Slush openly described the proposal and asked the community to help him find errors.

Success brought more power and with it responsibility. The larger the part of the network the pool aggregated, the more sensitive every outage or bad decision became. The service had to protect accounts, calculate rewards, and respond to attacks. This was no longer just a script to even out luck; it was infrastructure that foreign people relied on for their accounting.

Block 97,834 is therefore not significant because of its amount. Other miners also earned the same fifty Bitcoins. What was exceptional was the way they got there and how they divided it. A single line in the blockchain represented the joint work of many machines and the first practical proof that pooling could work in a public network.

The project later went through the names Slush Pool and Braiins Pool. The Braiins team professionalized the service, while Marek Palatinus devoted more energy to SatoshiLabs and the Trezor hardware wallet. From the original server, however, an uninterrupted historical line remained to one of the oldest names in Bitcoin mining.

Pooling expanded the possibility of mining but also gradually concentrated the creation of block templates into a smaller number of services. A solo miner decides for themselves what block to build. A participant in a regular pool often just calculates the assignment they received. Physical power can be distributed, while coordination decisions remain centralized.

This concentration does not mean that the pool owns all the connected machines. Miners can redirect their power elsewhere if they disagree with fees, censorship, or the operator's behavior. However, a change requires information and a willingness to react. Decentralization is therefore measured not only by the number of devices but also by who assembles blocks and how easily the coordinator can be changed.

Slush's first text did not conceal this compromise. He offered a solution to an economic problem and at the same time named the trust that the solution requires. It is this openness that helps to read the story without later triumphalism: the pool was not the final answer but a new tool with clear costs.

The Prague project changed mining by separating work from luck. An individual no longer had to win the entire block for their hashrate to get a continuous price. At the same time, it showed that even a system designed without a central bank would create services that people entrust with coordination. The question is not whether they will arise but whether participants can control, leave, and replace them.

The concentration of pools therefore cannot be measured by the number of connected machines alone. What matters is who assembles the block template, selects transactions, sets payout rules, and can convince participants to change software when a problem arises. A miner can leave a pool only if he has another usable option and actually keeps track of what the service is doing. Slush's original description of trust remains relevant in this regard. Pooling solved a real economic problem and at the same time created a new domain in which competition, transparency, and the ability to exit are necessary. Decentralization is not maintained by forbidding coordination, but by not letting it harden into unchecked power.