Fan Fei throws a needle into the glass, she pierces it and detonates a balloon on the other side. Time-lapse photography shows that the needle is indeed going through the glass. When other people tried to repeat this trick, they only managed to break off a small piece of glass. How does a monk do it? Cornwell University glass researcher James Setna told LiveScience: “Glass is actually very hard as long as it doesn't crack. But when a crack appears, it becomes very brittle."
The fact is that glass molecules form sufficiently strong bonds with each other, when pressing on one area, the force is transferred to another and is distributed over the entire surface of the glass. But when its integrity is violated, the force accumulates at the edges of the crack, so much less forces are required for destruction. Setna explains the needle trick as follows: a stiff needle makes a deep crack in the glass. When there is a crack, it is much easier to break through the glass itself.
Tatiana Lehatkova