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Physics
Classical Physics
Optics
Interference - two waves of different frequencies - beat velocity
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[QUOTE="andrewkirk, post: 6614193, member: 265790"] The modulation speed need not be limited by c because it is not the speed of a particle or wave. It is the speed of a feature in a pattern, which is an abstract, non-physical concept, and hence not limited by the speed of light. As another example of how this can happen, consider a powerful, perfect laser mounted perpendicularly on an axle in the middle of a sphere with radius one light second and pointing directly at the sphere's inner surface. The laser rotates on the axle at a rate of one full rotation per 3 seconds, so that the dot of light it makes on the sphere's inner surface traverses a full equatorial circle of the sphere in that time - distance covered = 2 pi light seconds - more than twice the speed of light. Yet the laser itself is only moving quite slowly. This can happen because the only thing moving on the sphere's inner surface is a feature in a pattern - not a physical thing limited by c. [/QUOTE]
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Physics
Classical Physics
Optics
Interference - two waves of different frequencies - beat velocity
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