Mohs scale of mineral hardness finding the hardest material that the given material can scratch, or the softest material that can scratch the given material. For example, if some material is scratched by apatite but not by fluorite, its hardness on the Mohs scale would fall between 4 and 5. "Scratching" a material for the purposes of the Mohs scale means creating non-elastic dislocations visible to the naked eye. Frequently, materials that are lower on the Mohs scale can create microscopic, non-elastic dislocations on materials that have a higher Mohs number. While these microscopic dislocations are permanent and sometimes detrimental to the harder material's structural
Measuring the Universe Measuring the Universe Measuring the Universe is a performance art work by Slovak artist Roman Ondak first installed in the Pinakothek der Moderne in Munich in 2007. The exhibition stars as a blank white wall and begins to fill when museum guards mark visitors' height along with their name and the current date. It is in the collection of Tate Modern in London, Pinakother der Moderne in Munich and MoMa in New York. The only items required for the installation were a white room and a few black markers. What began as a clean white space has been filled with