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New Experiment Reveals Sound, Not Light, Moves Through Metal

11/28/2025

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Summary

Story summary

A hypothetical metal pole from England to France cannot transmit motion instantly; the disturbance travels at the speed of sound, not the speed of light.
Pulling one end creates a wave that propagates along the pole, so the other end moves only after the wave arrives.
A tabletop experiment shows the propagation speed is far slower than light, taking about 6.43 seconds for a 33-kilometer pole, highlighting the difference.

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Story summary

A hypothetical metal pole from England to France cannot transmit motion instantly; the disturbance travels at the speed of sound, not the speed of light.
Pulling one end creates a wave that propagates along the pole, so the other end moves only after the wave arrives.
A tabletop experiment shows the propagation speed is far slower than light, taking about 6.43 seconds for a 33-kilometer pole, highlighting the difference.