eli5: On an atomic level, how does an atom ‘know’ it belongs to (for example) a sheet of paper but not the sheet of paper below it. Also how do scissors interact with the paper on an atomic level to cut it into two pieces.
In: Physics
>eli5: On an atomic level, how does an atom ‘know’ it belongs to (for example) a sheet of paper but not the sheet of paper below it.
It doesn’t. Look up vacuum welding, it’s fascinating. When you have two very clean surfaces of, say, aluminium, and touch them together in a vacuum, they will weld themselves together because yes the atoms don’t ‘know’ which piece of metal it’s a part of. The reason they don’t in your everyday experience is because our environment is full of oils, and dirt, and oxygen corroding the metal, so there are multiple dividing layers between the actual metal.
Of course paper is less simple since it’s actually a bunch of fibres mashed together.
>Also how do scissors interact with the paper on an atomic level to cut it into two pieces.
The scissors blades compress the paper fibres until they break apart. Scissor blades aren’t lined up for a reason, what they’re doing is basically pulling the paper apart, just in a very small area. It’s why very blunt scissors don’t cut, they bend the paper instead; the area on which they’re pulling is too large, and the force of your hand isn’t great enough to pull that many fibres apart
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