Exploring the Physics of an Instantly Rigid Metal Pole Extending to Pluto

Hypothetically, if you were holding a metal pole that extended to Pluto and turned it in 2 seconds, the laws of physics would place significant constraints on this scenario. Most answers suggest the impossibility of such an object due to fundamental physical limitations. However, let's consider a thought experiment where the pole is perfectly rigid, instantly reactive, very lightweight but of non-zero mass. What would happen then?

Energy Requirements and Physical Limits

The energy required to move the pole would increase dramatically as you turn. As the end of the pole approaches the speed of light, the energy demands become extreme, far surpassing what any known bounding mechanisms can handle. One would contend that the energy imparts itself at a rate that would lead to death from the energy imparted well before reaching light speed.

The far end of the pole wouldn't move until all the forces had propagated atom by atom throughout its length. This is because the transfer of forces happens via electromagnetic interactions between atoms, a process limited by the speed of light. Hence, an object that is rigid in the everyday sense of the word (such as a broom or PVC pipe) would exhibit properties that lead to the end moving only after a delay corresponding to the speed of light.

Practical Considerations: A Lengthy Lever

The situation described is akin to a lever where the force is incredibly close to the fulcrum. For an impossibly long pole, the force applied at one end is essentially the same as the fulcrum. This highlights that the longer the lever, the more force is required to accelerate it. This concept can be tested easily using a shorter pole: a broom, for example.

Rotate the broom with hands together, which allows for a swift motion with minimal movement. When holding it at a longer distance from the fulcrum, significantly more force is required over a longer period to achieve the same rotational speed. This illustrates the principle that longer lengths require more force to accelerate.

Realistic Constraints and Material Limitations

Even in a purely hypothetical scenario, the laws of physics impose significant constraints. Attempting to achieve such motion with an actual object would likely result in it breaking long before reaching even a fraction of the speed of light. PVC or any other material we have today would bend or break under the stresses involved. The lag in motion would be noticeable, and the forces required would be immense.

Thus, while the concept is intriguing, the practical and theoretical limits of physics and material science make it an impossibility in our current understanding of the universe.