Precision Measurement

We've come a long way from the days when the length of the king's forearm was used to determine an object's size. Then, it was called the cubit, but the succession of short- and long-limbed kings made uniformity difficult. More modern standardized measures have helped. But these days, even those aren't enough. That's why the agency that sets measurement standards for the United States - the National Institute of Standards and Technology - is asking American technologists to assess the needs for new ones. With 80 percent of world trade dependent on such standards, NIST wants to be up to speed.

The world's most accurate "ruler" made with extreme ultraviolet light has been built and demonstrated with ultrafast laser pulses by scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.