All That Matters

The Boeing 787 Dreamliner is the most recent major new aircraft design from Boeing, and the manufacturer’s most fuel-efficient plane. I have never had the pleasure of being passenger on one of these, but the design is certainly very modern. Composite materials are widely used in the aircraft, which is key to the plane’s fuel efficiency and explains the popularity of the plane. With more than 800 orders in the books, Boeing was also on a good track to break even commercially.

Then, on January 16 the FAA grounded all 787, following a number of technical problems. Earlier, the Japanese airlines ANA and JAL had already suspended all 787 flights, which was a significant signal because combined these two airlines operate almost half of the 787 delivered to date. Aside from a number of other technical issues such as a fuel leak, a key reason to ground the entire fleet has been two incidences where the back-up batteries overcharged and overheated such that there was the danger of fire on board. But how big a deal are these battery incidents? […]

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. […]

Usually we tend to think about temperature as being related to the motion of atoms. At lower temperatures, atomic motions slow down. Absolute zero, defined as zero Kelvin or −273.15 degrees Celsius, then is the point where all atomic motion stops. But what comes beyond that, does something like a negative absolute temperature exist? Indeed, as Ulrich Schneider and colleagues from Munich have now demonstrated impressively in this week’s issue of Science, it does. […]