Vectors: Feynman's Physics Explained

Feynman Vol I6-7

The laws of physics do not care whether you run an experiment here or there, facing north or facing east — they must be the same regardless of how you orient your coordinates. To capture this we invented the vector: not just three numbers, but three numbers that transform together in a special way when you rotate your axes, just like the coordinates of a point. Writing laws as vector equations, like F = ma, guarantees they respect this deep symmetry of space.

The big idea

Vectors let the laws of physics look the same in any direction.

Think about it

Why is 'go 5 km' an incomplete instruction, while 'go 5 km northeast' is complete?

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