Ultraflat materials can be stuck together via wringing

Phil Moriarty looks at an interesting phenomenon called wringing, where it's possible to press two pieces of steel together and make them adhere, without the use of adhesives, magnetism, or other outside forces. It can also be done with precision-milled silicon and glass. In order for this to happen, the material has to be milled to extremely tight tolerances. The easiest to find are steel gauge blocks, used for precision measurements.

It's not fully clear yet why this happens, and it may be a combination of causes.

Image: YouTube / Sixty Symbols