(NIST: Gaithersburg, MD) -- Researchers at the National Institute of Standards and Technology (NIST) have for the first time used an apparatus that relies on the “noise” of jiggling electrons to make highly accurate measurements of the Boltzmann constant, an important value for many scientific calculations. The technique is simpler and more compact than other methods for measuring the constant and could advance international efforts to revamp the world’s scientific measurement system.

The Boltzmann constant, with an accepted value of 1.3806504 x 10^-23 joules/kelvin, currently relates energy to temperature for individual particles such as atoms. The accepted value of this constant is based mainly on a 1988 NIST measurement performed using acoustic gas thermometry, with a relative standard uncertainty of less than 2 ppm. The technique is highly accurate, but the experiment is complex and difficult to perform. To ensure that the Boltzmann constant can be determined accurately around the world, scientists have been trying to develop different methods that can reproduce this value with comparable uncertainty.

The latest NIST experiment used an electronic technique called Johnson noise thermometry (JNT) to measure the Boltzmann constant with an uncertainty of 12 ppm. The results are consistent with the currently recommended value for this constant.

 …