Speaker
Description
On 16 November 2018, the 26th General Conference on Weights and
Measures adopted the new International System of Units (SI). The new
definition of the base units, including the kilogram, is based on a choice
of universal constants. This is the culmination of a long process that
began on 26 March 1791. This presentation will review this scientific and
historical adventure, the importance of units and their definitions and
the choice of defining them on the basis of natural constants. This will
require us to look again at the role of constants in the laws of nature:
What is a constant? How can we be sure that they remain constant? What are
their links with the units and tests of general relativity? These topical
questions will prompt us to consider some recent advances in theoretical
physics, as well as the history of the evolution of scientific ideas over
more than two centuries... and open an unexpected new window on the
search for dark matter and dark energy or any new physical degree of
freedom, a key issue in modern cosmology!