Delay of Reaction: Would a Pole Between England and France Create an Instantaneous Pull?
LONDON – teh seemingly instantaneous nature of cause and effect is challenged by the fundamental speed of physics. While we perceive actions as immediate, even a solid connection across the English Channel would introduce a noticeable delay. A recent exploration of this concept,spurred by online discussion,demonstrates that even transmitting a force through a solid material isn’t instantaneous.
Material scientist Brian Haidet, on his YouTube channel AlphaPhoenix, conducted an experiment illustrating this delay. He tested the transmission of a mechanical signal - a hit – through a metal pole, finding the time it took for the signal to travel matched the expected speed of sound within the steel.
Sound doesn’t travel at a single speed; it varies depending on the medium. On Earth, sound travels at approximately 1,500 meters (4,921 feet) per second in water, and around 340 meters (1,115 feet) per second in air. In solids, the speed is substantially faster, but still finite, dependent on the material’s properties like its “bulk modulus” – a measure of its resistance to compression. As the University of Illinois Urbana-Champaign explains in its “Ask The Physics Van” feature, ”A little ripple in the density of a piece of steel creates much bigger forces then a similar percentage ripple in the density of some air. So those bigger forces speed up the sound.”
To illustrate the delay across the english Channel, consider a hypothetical iron pole stretching the shortest distance between England and France: 33 kilometers (20 miles). Assuming a sound speed of 5,130 meters per second in iron, it would take approximately 6.43 seconds for the force of a pull at one end to reach the other.
This contrasts sharply with the speed of light,which would complete the same journey in a mere 0.00011 seconds, highlighting just how quickly information - and forces carried by electromagnetic radiation – travels compared to mechanical transmission. While 6.43 seconds isn’t an insurmountable delay, it definitively proves that even through a solid connection, a truly instantaneous reaction is unachievable.
