APRIL 9
Proof of Work
Real Work Behind Every Block
The Signal
New bitcoin enters circulation only after machines perform costly, verifiable computational work.
The Reading
Imagine a machine facing a locked door. It cannot talk its way through or call a powerful friend. It must keep trying digital keys until one fits. Finding that key takes equipment, electricity and time. Checking it takes only a moment.
This is proof of work, deep inside the Bitcoin engine room. A miner gathers waiting transactions into a block. Special machines make enormous numbers of attempts, searching for a result that meets Bitcoin’s strict target. Almost every attempt fails. When one succeeds, the miner sends the block and its proof to nodes.
Nodes check the proof quickly, then check every Bitcoin rule. If anything is wrong, they reject the block, however much the miner spent. If everything is right, the block joins the shared book. Only then can the winning miner receive newly issued bitcoin and transaction fees.
Proof of work makes valid blocks costly to produce on average. Behind it are machines, power and planning. Promises are cheap. A valid proof must be found. Changing a block means redoing its work and catching the honest chain. This gives history weight.
First Principles
Proof of work is costly to produce but very quick to check.
New bitcoin enters circulation only through a valid mined block.
Work never gives miners permission to break rules.
Today’s Challenge
Open YouTube on your television and choose a specific video to find.
Do not use voice search, viewing history, a saved link or the creator’s channel. Start a timer. Using the remote and YouTube’s search bar, type the video’s name and work through results until you find the correct one.
Now show the screen to someone else. Ask them to check the title and confirm you found the right video. Checking takes only a moment.
Notice the difference. Finding the result required time, button presses and perhaps several wrong choices. Verifying it was easy.
Bitcoin miners also perform repeated computational work to find an acceptable result. Nodes check that result quickly. This is proof of work: difficult to produce, easy to verify.
Tomorrow’s Signal
Energy Becomes Security