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@@ -54,6 +54,6 @@ when continuity breaks — phase transitions, tipping points, market crashes —
[measurement](/wiki/immediate/counting-and-measurement) gives you a snapshot. calculus tells you the story — how things are changing, where they're heading, what they'll add up to. it's the mathematical upgrade from static to dynamic thinking.
-[physics](/wiki/stem/physics) is where calculus was born: Newton invented it to describe motion. but the thinking patterns — rates, accumulation, limits, continuity — are universal. any time you're reasoning about change, you're doing calculus, whether or not you write down an equation.
+[physics](/wiki/stem/physics) is where calculus was born: Newton invented it to describe motion. but the thinking patterns — rates, accumulation, limits, continuity — are universal. any time you're reasoning about change, you're doing calculus, whether or not you write down an equation. in [[stem/biology-and-medicine|biology]], calculus describes population growth, enzyme kinetics, and the spread of disease — every differential equation in the SIR model is calculus applied to living systems.
-and when the change happens in multiple dimensions simultaneously, you need [multivariable calculus](/wiki/structural/multivariable-calculus-as-thinking) — gradients, divergence, curl — which extends these ideas into the full complexity of real-world systems.
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+when the change happens in multiple dimensions simultaneously, you need [multivariable calculus](/wiki/structural/multivariable-calculus-as-thinking) — gradients, divergence, curl — which extends these ideas into the full complexity of real-world systems. and when calculus meets [[structural/linear-algebra-as-thinking|linear algebra]] — as it does in finite element analysis, neural network training, and dynamical systems — the two frameworks reinforce each other: linear algebra provides the structure, calculus provides the motion.
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