APRIL 10
Energy Becomes Security
Making Security Physical
The Signal
Bitcoin uses electricity to make mining work costly and impossible to fake.
The Reading
Yesterday we pictured a mining machine trying digital keys until one fitted a lock. That was a simple picture, not a real Bitcoin key. The machine is testing one answer after another, trying to solve a mathematical puzzle by finding an answer that meets Bitcoin’s strict target. Almost every answer fails. Finding one that Bitcoin accepts can require an enormous number of attempts.
Every attempt is a piece of computation. Computation needs machines. Machines need electricity. Each attempt uses a tiny amount. Vast numbers of attempts use a lot of energy. When a miner finally finds an acceptable answer, the result proves the work was done. It cannot be produced by merely saying it happened.
In the engine room, all this gives Bitcoin something truly special. A person can invent a thousand names or open a thousand accounts cheaply. Names do not create mining work. To produce more proof of work, someone needs more machines, electricity, time and money. Pretending is cheap. Proving is not.
This is how energy becomes security. It gives every attempt a physical cost. A successful result still gives nobody permission to change Bitcoin’s rules. Nodes check the block and reject anything invalid. Bitcoin does not count promises, names or importance. It counts work that can be proven.
First Principles
Mining machines need electricity for every answer they test.
A rare successful result proves that real computational work was performed.
More mining work requires more machines, electricity and physical cost.
Today’s Challenge
Cut five pieces of paper. Write a name on each. One person created five identities in moments. Names are almost free.
Place five coins 2.5 metres away and a bowl beside you. Carry them to the bowl one at a time, returning for each coin.
Names required almost nothing. Every coin required movement, time and energy. More names could not carry the coins.
As a rough example, miners need about 570 sextillion attempts on average to find a valid block and release bitcoin. If each attempt were one five-second coin-carrying trip, the work would take about 90 quadrillion years.
Bitcoin does not count names. It counts proven computational work. Electricity gives that work a physical cost. That cost is the foundation of Bitcoin’s security.
Tomorrow’s Signal
The Difficulty Adjustment