Elasticity

Elasticity measures how strongly one economic variable responds to a change in another, most commonly how much the quantity supplied or demanded changes when price moves. A good is elastic if a 1 percent price change moves quantity by more than 1 percent, and inelastic if quantity barely responds, as with gasoline demand or, more extreme, gold supply, which grows only about 1.5 to 2 percent per year regardless of price.

Why it matters

Elasticity determines who bears the burden of shocks and taxes, how violently prices swing, and whether high prices cure themselves. In elastic markets, price spikes summon new supply and fade. In inelastic markets, the same demand surge goes almost entirely into price, which is why housing in constrained cities, commodities with long mine lead times, and collectibles can move so dramatically.

Monetary economics turns on the same concept. Fiat money supply is perfectly elastic, expandable at will by central banks, which is presented as a stabilizing feature in crises and criticized as an inflationary temptation the rest of the time.

In the gold vs bitcoin debate

Bitcoin is the first money with perfectly inelastic supply: no price, however high, can produce more than the schedule allows, since difficulty adjusts to absorb new mining effort. Gold is nearly inelastic but not quite, as sustained high prices do eventually expand mine output. Advocates frame bitcoin as the logical endpoint of the property that made gold money, while critics answer that perfect inelasticity guarantees permanent volatility, since supply can never cushion demand swings.