Thinness of the edge apex

[EOU]

Now that's an interesting way to think about it Jan! We're embarrassed that you were the one to make the association because that's the field (optics and lasers) that most of here share. I think we have it though - If you have to use a blacklight to see your knife edge (UV) it's very sharp and if you have to use an IR illuminator to see the edge it's very dull.    

We like to make jokes around here - we just don't make very funny ones.