Explanation
The cost of energy makes attacks expensive. Bitcoin uses this model; the debate about energy use depends heavily on the source of that energy.
Computation as the lock on the door
Miners use brute computing power to search for a number that, together with the block, produces a fingerprint below a certain threshold. That costs electricity and time, and precisely that cost makes rewriting history expensive: an attacker must redo all the work since the target block and outpace the rest of the network.
Energy and the real debate
Consumption is substantial and cannot be argued away. The substantive debate is about which electricity is used: miners chase the cheapest energy, pushing them toward surpluses, curtailed wind and solar output and flared gas. In Europe the discussion is mainly political, with periodic proposals to restrict proof of work.
Key takeaways
- Security bought with real energy.
- Difficulty adjusts roughly every two weeks.
- Bitcoin is the main network still using it.