bike tire spinning
How does time behave near a black hole?
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...
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
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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Update: June 2012