Probability: Feynman's Physics Explained
We make guesses because we rarely have all the information. Probability is a system for making better guesses. Picture a drunk man taking steps at random: on average he ends up nowhere, yet he does drift away from the start. Remarkably, the average of the square of his distance grows in proportion to the number of steps. This 'random walk' is a powerful model for diffusion of gases and many other natural processes — showing that even in pure chaos, predictable laws emerge.
The big idea
Randomness on the small scale produces reliable laws on the large scale.
Think about it
Flip a coin 10 times, then 100 times. Why does the fraction of heads get closer to one-half as you flip more?
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