Why people believe this
Measurement in classical physics reads a property the system already had. A thermometer reads the temperature that was already there. It feels natural to assume quantum measurement works the same way.
The correction
In quantum mechanics, measurement is not passive. It actively collapses the wavefunction — the act of measuring creates the definite outcome. Bell inequality experiments have proven that quantum systems do not have hidden pre-existing values. The outcome is genuinely random and only becomes definite at measurement. This is not a limitation of our knowledge — it is a fundamental feature of quantum mechanics confirmed experimentally.
Try it in the simulator
What to do
Load the Measure demo preset. Run it 10 times. Each run collapses q0 differently — sometimes 0, sometimes 1. The result is not determined before measurement. Notice gates after M operate on the collapsed classical state.
Research notes
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