This is a thought experiment.
Imagine that science has figured out how to make the ultimate slicing tool, for use in… whatever the hell they’d need it. For simplicity, let’s say it’s made of tungsten.
If you held the blade vertically, sharp end up, it would be shaped like two-dimensional pyramid. The tip of the blade is one atom thick. Two atoms below the tip, three atoms below that, etc.
1: How many atoms thick would it have to be before I could see anything? I’m guessing it would be in the quadrillions of atoms.
Looking at the blade with the naked eye, would I be able to see a definitive edge to the blade, like I can with a run-of-the-mill Gillette blade? Or would it look… I dunno, fuzzy?
What would happen if I put my finger to it? I imagine that it would slice so cleanly and painlessly that I wouldn’t notice anything amiss until my finger was severed.