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Faster than speed of light?
Suppose a very fast light source revolves at 10,000 revolutions per second, and the light shines on a circular wall surrounding the source which has a circumference of 20 miles. Then the beam of light appearing on the wall moves at 200,000 miles per second, faster than the speed of light. Two questions (a) does the beam indeed move at 200,000 miles per second? (b) if so, how does this not violate relativity ?
feedback on 1st 4 answers: Thomas: What refraction? Andrew, Ronald: I agree with what you say but you haven't answered whether the light spot on the wall can move faster than the speed of light. Anthony: I'm not asserting that the disk moves, only the light spot.
5 Answers
- Anonymous10 years agoFavorite Answer
Let's allay others objections, we'll have a tiny mirror rotating at 10,000 rps, and a laser shining down on its rotational axis. 10,000 rps is not out of the realm of possibility.
http://en.wikipedia.org/wiki/Orders_of_magnitude_(...
... microturbines to 33000 rps, and a flake of graphene to 100000 rps
a) No, the beam moves at c, for all inertial observers. Between the wall and the light source there will be one or two "batches" of photons at any given time.
b) no violation
Additional Details response...
The "spot on the wall" is not anything physically moving. This is no different than "superlumenal scissors".
- Ronald GreeneLv 710 years ago
(a) The beam of light does not travel at 200,000 miles/second. Visualize if you will, a garden hose spraying water. No matter how fast you move the garden hose through an arc, the water still issues from the nozzle at a fixed rate. The speed of light according to Einstein, is 186,000 miles/second.
(b) is answered by (a)
- Anonymous10 years ago
The answer is that you would never get the edge of the disk to travel at 200,000 miles per second, because you would need an infinite amount of energy to do it. If you wanted something to spin at 10,000rpm, it would need a smaller radius.
- Anonymous10 years ago
light travels at 186000 mps. no matter the speed of the lightsource. you do not add or subtract to the velocity of light regardless of the velocity of its source. i hope you can understand this.
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