Imagine this: you have an incredibly long metal pole, stretching all the way from England to France. Now, if you were to give it a good yank at one end, would the person holding the other end feel the pull instantly? This thought experiment has sparked some fascinating discussions on Reddit, with Redditor gothreepwood101 posing an intriguing question.
The answer might seem straightforward at first. After all, metal is solid, right? So, a force applied to one end should instantly transmit to the other. But here's where it gets controversial...
If you said 'yes' to an instant yank, you've just broken a fundamental rule of the universe! You've essentially proposed that you can affect something faster than the speed of light, which is a big no-no in physics. The speed of light, an incredible 299,792,458 meters per second, is the cosmic speed limit. Nothing, not even our theories, can surpass it.
But let's delve deeper. Some might guess that the other end would move at the speed of light. While this is more plausible than instantaneous travel, it's still incorrect. The issue lies in our understanding of solids.
When we look at a metal pole, it appears continuous and solid to our eyes. However, if we could shrink ourselves down to the microscopic level, we'd see a crystalline structure made up of nucleons and their electrons, held together by electromagnetic forces. This microscopic network of particles is what gives the pole its strength, but it also means that when you apply a force, it spreads like a wave, at the speed of sound in that material.
Material scientist Brian Haidet demonstrated this delay by hitting a pole at one end and detecting the signal at the other. The delay matched the speed of sound in steel, a neat and simple experiment.
So, how long would it take to yank your French friend or English enemy?
It's still pretty fast, but not instantaneous. The speed of sound varies depending on the medium. In water, sound travels at around 1,500 meters per second, while in air, it's about 340 meters per second. In solids, it can be much faster, but it depends on the material and factors like temperature, pressure, and the bulk modulus.
For example, if we consider an iron pole with a simplified speed of sound of 5,130 meters per second, and assume the shortest distance between England and France is 33 kilometers, it would take approximately 6.43 seconds for the force to transmit from one end to the other.
That's a considerable wait compared to light's 0.00011 seconds, a stark reminder of just how fast light travels.
So, the next time you consider yanking on that pole, remember the physics behind it! And feel free to share your thoughts and interpretations in the comments. Is there a way to make this experiment more accurate or interesting? What other factors might come into play?
