If you had a superstrong catwalk a light year in length, shaking it at one end would only cause the other end to shake after a year.
light year = distance light can travel in a year at it's speed
i believe vibrations do not transfer at the speed of light.
so it would take much much much longer for that energy to reach the end.
if it worked like that, Kalphiter's statements would be laughably invalid. that's basically implying that the amount of energy you would put into mixing a protein shake is all it takes to travel at the speed of light, meaning while you shake your drink to mix it, your hand is traveling back and forth at the speed of light or close to it.