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Problem #109 MEDIUM

The Speed of Information — Can You Beat Light?

Paradox Physics Logic

Problem Statement

A 1-light-year-long rigid rod connects two people: Alice on Earth and Bob at Alpha Centauri. Alice pushes one end of the rod. Does Bob feel the push instantly, transmitting information faster than light? Now suppose instead of a rod, Alice and Bob each hold one particle of an entangled quantum pair. Alice measures her particle and instantly 'collapses' Bob's particle to a definite state. Has information travelled faster than light? Both scenarios seem to allow faster-than-light communication. Both are wrong — for different reasons.

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