Bumps in example sentence
Each mirror, there are four of them, is made of a single piece of glass, a monolithic piece of high-tech ceramic, that has been ground down and polished to such accuracy that the only way to understand what that is is [to] imagine a city like Paris, with all its buildings and the Eiffel Tower, if you grind down Paris to that kind of accuracy, you would be left with bumps that are one millimeter high.