On Reddit, a user posed an intriguing physics question: if a metal pole extended from England to France and one person pulled one end, would the other end move instantly? At first glance, it seems intuitive that it would, but this violates the universal speed limit set by the speed of light (approximately 299,792,458 meters per second).
The real answer lies in understanding how solids behave. When one end of a metal pole is pulled, the movement doesn’t travel instantaneously. Instead, the first atomic layer of the pole pushes the next layer, creating a wave of motion that travels at the speed of sound in that material.
This speed varies depending on the medium; in solids like steel, sound travels much faster than in air or water. For a steel pole, assuming a speed of sound at 5,130 meters per second, it would take approximately 6.43 seconds for the other end to respond over a distance of 33 kilometers (20 miles). This delay is significant when comparing it to the incredibly quick speed of light, which would cover the same distance in just 0.00011 seconds.
In essence, while the idea of instant movement is appealing, the physics of sound and the structure of materials reveal a more complex and slower reality.
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