All That Matters

How do you measure mass with high precision? This is not an easy question, as it is very difficult to measure the weight of something with the same ultra-high precision with which atomic clocks measure time. To this day, the kilogram is defined by a piece of metal made of platinum and iridium that is stored in Paris. If you want to know with absolute precision the weight of something, you would have to compare it to this particular piece of metal. This does not only seem very imprecise and old-fashioned, it also leads to a range of issues. Only last week there have been news reports of the official kilogram piece and its various official copies all over the world slowly gaining weight from dirt on their surface.

It comes as no surprise that physicists are searching for more precise ways to measure weight, and the method now published in Science by Holger Müller and colleagues from Berkeley is one of the most elegant and beautiful ones that I have seen in a long time. It is based on a quantity that we know very well how to measure with very high precision – time. The question is how to measure the mass of something by telling the time. […]

Image by NathanaelB via flickr

They were pretty common with bands at least in the 1970s and 1980s, and probably still are – electronic synthesizers. Just check out video and sound of this Depeche Mode song ‘Just can’t get enough.’ Synthesizers generate artificial sounds by breaking these down into their individual frequency components and then generating these components artificially. In a paper published in Science this week, Andy Kung and colleagues from the Institute of Atomic and Molecular Sciences of the Academia Sinica in Taiwan and other Taiwanese institutions have now demonstrated the equivalent of electronic synthesizers, but for light. […]