APRIL 8
Mining
Building Bitcoin’s Next Block
The Signal
Bitcoin miners compete to build the next block, but Bitcoin accepts it only when every rule is followed.
The Reading
We have finished exploring Bitcoin’s Shared Book. Today we open a new door and enter the Engine Room. Imagine a giant book with payments waiting for its next page. Someone must collect them, place them on a page and offer it to the book. Bitcoin has no head office or chosen bookkeeper, so people around the world run mining machines. Each miner gathers payments into a possible block. Many miners compete to complete the task Bitcoin sets. This race uses computers and electricity, so taking part costs something real.
When one miner succeeds, it sends its block to the Bitcoin network. Thousands of checking computers, called nodes, inspect it. They ask: Are the payments valid? Does the block follow every rule? One broken rule causes the whole block to be refused. If every check passes, the block joins the chain. Its payments receive their first confirmation, and the successful miner receives a reward under Bitcoin’s rules.
This division matters. Miners build and offer the next page. Nodes decide whether it belongs in the book. Electricity cannot buy permission to break Bitcoin’s rules. The Shared Book holds the record. The Engine Room keeps adding new pages.
First Principles
Miners gather waiting payments into a possible block.
Miners compete in a race using computers and electricity.
Nodes check the winning block and reject it if a rule is broken.
Today’s Challenge
Find an envelope and five pieces of paper. On one, write: “No payment over $10.” On the other four, write $3, $6, $8 and $14. Put the four payments inside the envelope. You are the miner, and the envelope is a block offered to Bitcoin.
Now become a node. Open the envelope and check each payment. The $14 payment breaks the rule, so reject the whole block. Replace it with $9 and check again. Now accept the block and place it behind a book.
You have acted out mining. The miner built and offered a new page, but the node decided whether it belonged. Mining uses machines and electricity for the competition, but spending cannot make a broken block valid.
Tomorrow’s Signal
Proof of Work