Spinning Really Fast

[kermit911]

Example: When a helicopters blades are spinning you can see through them. My ? is, Can something spin so fast, you can't see through it?

[Loosehead]

Only if there are no gaps. The spinning emphasises the gaps, the brain makes the pictures by effectively putting together a lot of smaller pictures.

[MargeB]

The visual brain does not know what pictures are, it creates this illusion in consciousness. The visual brain works only with objects and proto objects.

[stevie21]

One reason why this would be impossible is that the rotor blades would have to travel faster than the speed of light for this to work.
Another potential reason is infinitely more complicated and involves something I don't really understand : duality in quantum physics. I think I'll just leave it at that rather than blunder my way through a fuller explanation but either way the answer's "no"

[MargeB]

blunder an explanation anyway, steve, I'm all ears.

[NetSquirrel]

You would still be able to "see through" the blades no matter how fast they were spinning, as Loosehead has pointed out.

Once the object is spinning sufficiently quickly, we just see it as a circular blur.  How see-through this blur is basically depends on how big/wide the spinning object is.  (More accurately, it depends on what percentage of the full circle the object "takes up" when it is stationary.  Assume the object is fully opaque to begin with)

I've made a brief animation to show this.  The semicircle takes up 50% of the area of the full circle.  So, once it is spinning so fast that it's a blur, the blur has an opacity of 50%.

[stevie21]

MargeB, you first. There was at least one sentence in my post that made sense and was relevant. You've some catching up to do ;-)

I hate being called Steve!