This video went viral on social media, showing a man running his finger over a moving blade without getting cut. At first glance, it seems dangerous and even impossible, but the explanation lies in the technology behind this tool. Unlike a conventional blade, this one isn’t sharp. Its edges are grooved and coated with microscopic diamond particles. Instead of cutting directly, like a knife would, it wears down rigid materials through continuous abrasion. This abrasive process is what allows it to "cut" extremely hard stones. In the case of the video, human skin is much softer and more flexible than stone. Additionally, the man applied very little pressure when running his finger over the blade. As a result, it simply slid across his skin without causing any harm. This demonstration is impressive because it challenges our expectations about industrial tools. It shows how advanced technologies can be designed for specific purposes — in this case, working with hard materials — while re...