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Question:
How does time behave near a black hole?



Replies:
I think this is the stroboscopic effect - your eye does not really see the world in a continuous movie, but in snapshots taken maybe 1/10 of a second apart. So it cannot follow the individual spokes of the tire, and tries to associate each image of spokes with the next image it sees - ie. it tries to slow down the rotation as much as possible and about 50% of the time that means seeing it rotate backwards rather than forwards. I am not too sure of this explanation though - I think I have left some things out...

Arthur Smith


I just did a quick experiment with a stationary bike and did not see the effect you are referring to. Of course in this situation the m motion I perceived for the spokes may have been dominated by the observed motion of the rim of the tire. Normally, the dominant motion you would see would be the motion of the tire center relative to the background -- perhaps this leads to the perception of backwards rotation. By the way, the slow response of our eyes makes it possible for us to watch TV (which is actually about 30 complete pictures a second) without seeing it flicker. Each complete picture consists of two "interlaced" pictures so the screen is re-drawn 60 times a second.

gregory r bradburn



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