First question: two reasons that wouldn’t work: the stick would just break, obviously, but if it was a super duper stick, the torque required to accelerate the end past the speed of light is directly related to how long the stick is, so any increase in speed from a longer stick will be offset by the need to apply more force at your end. Therefore the energy required to flick a stick to the speed of light does not depend on the length of the stick, you are simply creating a reverse lever of sorts. It’s still an infinite energy requirement, assuming the stick has mass.
The second question is a lot easier. The light is traveling directly away from you at all times, there is no sideways motion.
It’s actually simpler: the stick will deform because whatever movement you do travels across the stick at the speed of sound of the material the stick is made out of.
Why does it matter how long it takes for the torque to travel down the stick? The question was about the speed of the tip in the orbital direction, not the speed of the wave in the radial direction outward.
I see your point. Still, it shows there’s no such thing as a “super duper stick” because there’d be shearing forces pulling the atoms apart faster than they can move together.
Yeah that’s the boring answer, it would just break apart. But even without physical limitations, mass has the property that it can’t be accelerared past c with a finite amount of energy, and I think it’s interesting to see why that limit is more fundamental than the structure of matter. No matter how you mess with forces using simple machines, the energy calculations always come out the same.
First question: two reasons that wouldn’t work: the stick would just break, obviously, but if it was a super duper stick, the torque required to accelerate the end past the speed of light is directly related to how long the stick is, so any increase in speed from a longer stick will be offset by the need to apply more force at your end. Therefore the energy required to flick a stick to the speed of light does not depend on the length of the stick, you are simply creating a reverse lever of sorts. It’s still an infinite energy requirement, assuming the stick has mass.
The second question is a lot easier. The light is traveling directly away from you at all times, there is no sideways motion.
It’s actually simpler: the stick will deform because whatever movement you do travels across the stick at the speed of sound of the material the stick is made out of.
Why does it matter how long it takes for the torque to travel down the stick? The question was about the speed of the tip in the orbital direction, not the speed of the wave in the radial direction outward.
I see your point. Still, it shows there’s no such thing as a “super duper stick” because there’d be shearing forces pulling the atoms apart faster than they can move together.
Yeah that’s the boring answer, it would just break apart. But even without physical limitations, mass has the property that it can’t be accelerared past c with a finite amount of energy, and I think it’s interesting to see why that limit is more fundamental than the structure of matter. No matter how you mess with forces using simple machines, the energy calculations always come out the same.