02 · The question

Measurement

Looking is an interaction. One shot, one bit, a new state. The Born rule turns amplitudes into chances; it does not reveal a hidden bit that was sitting there.

In English

Looking is not peeking. It is an interaction that returns one bit and leaves the qubit in that answer. Do it again and you get the same bit — the arrow already collapsed. Many shots on fresh copies reveal the chances.

Try this: Set a lopsided state. Fire one shot — the state jumps. Reset, fire many shots, and watch the histogram match the squares.
Keep this: One measurement, one bit, a new state. The Born rule is the chance, not a hidden label.

Lab · one shot, one bit

|0⟩
0.7150%
|1⟩
0.7150%

Born P(|0⟩) now 50.0%

Histogram · 0 shots

|0⟩

|1⟩

The Born rule: P(k) = |⟨k|ψ⟩|². A shot samples that distribution and replaces |ψ⟩ with |k⟩. There is no extra hidden bit that the measurement merely uncovered — if there were, interference in the next chapter would not work.

Repeat the same measurement and you get the same answer, because the state already collapsed. That is not “the true value was always there.” It is the new state.