Thursday

(Nanowerk News) Metrology is the science of measurement. Its aim is to ensure that measurement results are comparable and reliable worldwide, for example in industry or in scientific experiments. So-called fundamental constants, or unchanging physical quantities such as the speed of light or Planck’s constant, play an increasingly important role in this context. As their values are universal, i.e. independent of place and time, they enable the definition of highly stable units and ensure highly reproducible measurement results. Since 2019, the International System of Units SI (short for: Système international d'unités) has been based entirely on these constants. The precise measurement of electrical resistance turns out to play an important role here. “It turns out, that under certain conditions, electrical resistance of a two-dimensional material can have a universal value, defined by a ratio of Planck’s constant h and square of elementary charge e”, explains Kajetan Fijalkowski, a physicist at the Institute for Topological Insulators at the University of Würzburg (JMU) and the main author of the study (Nature Communications, "Quantum adiabatic transport in a quantum anomalous Hall insulator"). “Such characteristic is independent of any material property, making it excellent for reproducibility - precisely what one wants from a standard”.

Jacquet-Droz was a genius clock and watchmaker who created unusual novelty devices that mimicked human behavior. As they tended to look like dolls, the term “android” was used to refer to them. Many of his doll-like androids still exist, but not all. An example of one of his remaining ones is the Writer, who could actually use a quill pen to write up to 40 words on a tiny piece of paper.