Barber's pole - appear faster than light?

[kyle1320]

Hi, so imagine this: You have (for this theoretical situation) an entirely massless barber's pole. When it spins, the speed of the of the circumference of the pole is less than the speed the line appears to travel up (or down) the side of the barber's pole. If you were to spin the pole, could the line traveling up the pole appear to go faster than light, even though no physical part of the pole is traveling faster? Disregarding red / blue shift.

 

[Danger]

Welcome to PF, Kyle. Nothing physical is moving faster than c. It's the same idea as the spot of a searchlight sweeping at superluminal speed. The law of relativity states that no information can be transmitted at or above c; that is not violated by the circumstance in question.

 

[DaveC426913]

could the line traveling up the pole appear to go faster than light, even though no physical part of the pole is traveling faster?

It could. Just as if I pointed a flashlight at the Moon, then whipped it around to point it at Ceres.

The "beam" gets from Moon to Ceres - a distance of hunderds of millions of miles - in a fraction of a second.

Of course, the beam is no more a real thing than the imaginary line you attribute to points on the barber pole.