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Old Jun 24th 2008, 08:33 PM   #1
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Knife

Suppose there is a knife with infinitely small width and it is able to cut anything. I use this knife to cut an object into smaller and smaller pieces, to a certain extent, would the object not being able to cut into smaller pieces?
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Old Jun 25th 2008, 04:22 AM   #2
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Originally Posted by werehk View Post
Suppose there is a knife with infinitely small width and it is able to cut anything. I use this knife to cut an object into smaller and smaller pieces, to a certain extent, would the object not being able to cut into smaller pieces?
(shrugs) If the knife itself has an infinitesimal width then we are ignoring quantum effects, so you can cut the pieces as small as you like.

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Old Aug 7th 2008, 08:07 AM   #3
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I think you would reach to cut the object in such a way that all its elementary particles are separated. If you are herculean you would be able to cut even its protons and neutrons into quarks, but don't ask me what happens if you try to cut a quark!
EDIT : In fact, after having thought more about it, you wouldn't be able to cut anything because if it's infinitely tight, the knife wouldn't be anything. But you can assume it has a very small width (much smaller than any elementary particle which is impossible) and then you wouldn't be able to cut anything and your knife would simply pass between the particles without being able to separate them.
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Last edited by arbolis; Aug 7th 2008 at 02:07 PM.
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Old Aug 7th 2008, 03:18 PM   #4
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Originally Posted by arbolis View Post
...but don't ask me what happens if you try to cut a quark!
No comment!

Originally Posted by arbolis View Post
EDIT : In fact, after having thought more about it, you wouldn't be able to cut anything because if it's infinitely tight, the knife wouldn't be anything. But you can assume it has a very small width (much smaller than any elementary particle which is impossible) and then you wouldn't be able to cut anything and your knife would simply pass between the particles without being able to separate them.
(chuckles) I like this answer.

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