Let's say I have a stick that is 1 light year long and I

>>8559947
No.

each infinitesimal portion of the rod will not move until the infinitesimal portion of the rod preceding it moves and pushes it. the forcing signal you impart on the rod at your end cannot travel up the rod faster than light. You are basically creating a compression wave within the rod.

>>8559950
>infinitesimal
no

>>8559947
>Please respond
[laughter intensifies]
no it's not FTL communication because actual speed of stick's movement here depends on compression waves as >>8559950 rightly said
it means that the speed of communication is bound to the speed of compression waves, i.e. speed of sound in a particular medium

>>8559947
Why do people keep thinking that if you move something, the whole thing moves at once? when does something like this ever happen irl that makes you think that? go take your katana and swing it against the grain of the blade, is the tip of the blade moving at exactly the same time you start swinging? no, it lags behind a bit, the blade bends a bit. IF you want to see it more clearly, get a plastic ruler, or better yet, go stick your dick in jello, see the effect ripple outwards? all mater acts like this, if you poke a stick a ripple will travel at the speed of sound in the rod outwards, and the speed of sound is always less than the speed of light.

>>8559953
>he doesn't understand arbitrarily small values of epsilon in the limit as epsilon goes to zero

>>8559962
>he doesn't consider that matter is not a continuous medium

>>8559972
>he doesn't value the exceedingly accurate and predictive power of the admitted approximation that is continuum mechanics

>>8559977
>he uses continuum approximations instead of operating with terms of molecules and atoms that depict fundamentals more clearly

>>8559947

>light year long
>long

Why are you using year (time) as a way to measure distance?

>>8559947
When one part of the stick moves, the only reason the adjacent part moves with it is because of the electromagnetic forces between the molecules/atoms/whatever. And electromagnetic forces travel only at the speed of light.

When you push one end of the stick, you are actually sending an impulse from your end that will travel along the stick to the other end. It may help if you visualize the stick as a long spring or something.

We don't notice this finite travel speed for impulses in everyday objects is that they're so small that the travel time is totally negligible.

>>8559985
>he models a light-year long object in terms of atoms and molecules
boy

File: 2012-02-13-bothidiots.jpg (221KB, 900x483px) Image search: [Google]

221KB, 900x483px

>>8559985
>>8560022

No, the movement would be at the speed of sound through the stick. Would actually take about 75759.2 years Depending on the type of wood

>>8560022
>he doesn't model presumably solid objects in terms of atoms and molecules