3 ms·

If the main light pulse is traveling at the speed of light and the vortex travels with it, that implies that the vortex must have one edge traveling at 2x the s

• jwfxpr 10y ago
  From the article: >The rotation around an optical vortex does not concern the direction of the oscillating electric field (polarization), but rather its phase [1]. For example, the maximum of the field might initially be located just above the central axis of a light beam, and then a short time later it’s to the right of the axis, then below. This rotating phase gives the light an orbital angular momentum that can cause a charged particle within the beam to rotate. So no matter or energy is traveling or transmitting faster than light; a property of the system can be observed to change location faster than the speed of light half of the time. Properties of an object can _change_ at a rate faster than light could propagate in a vacuum, as long as they don't carry information. Imagine you are shining an incredibly powerful flashlight at the dark surface of the moon. You cover the light with your hand, and then uncover it again. An observer could record the edge of the shadow moving faster than light, but this doesn't mean any physical laws have been broken. No information, energy, or mass has moved faster than light.