On May 20, 1875, representatives from 17 countries met in Paris. In 1875, they signed the Treaty of the Metre, establishing an agreement between the countries that allowed them to cooperate internationally to establish standards for measurement. This historic agreement established the basis for the definitions of the metre and the kilogram. These units continue to be vital in our everyday lives and in advancing scientific discovery. The Treaty was a major milestone in creating an internationally recognized uniform system of measurement. It illustrated the nigh two centuries long evolution of this obscure unit.
The definition of the metre has changed dramatically since the original definition in 1791, keeping up with the progress of science and technology. Initially, the metre was defined as one ten-millionth of the distance from the North Pole to the equator, calculated through the Paris Observatory. This definition was pretty good until we figured out how to measure more exact measurements. In 1960, this development was enough to allow for a redefinition in terms of wavelength of light.
The Evolution of Measurement Standards
Over the centuries, the demand for agreed-upon standards of measure has been urgent. The Treaty of the Metre, signed by 17 states in 1875, codified this necessity by establishing the International Bureau of Weights and Measures (BIPM). This non-profit is responsible for keeping global measurement standards, creating the measurement’s uniformity across countries.
In 1983, they adopted a revolutionary new definition of the metre. It has, of course, now been redefined to be the distance light travels in a vacuum during 1/299,792,458 of a second. This ambitious definition hinges on the speed of light—an absolutely universal physical constant—which represents a psychological and concrete shift toward absolute precision in scientific measurements. About this change to the National Measurement Institute, Bruce Warrington, Director of the National Measurement Institute said,
“not from the length of the king’s arm, or something that changed over time.”
This shows how contemporary definitions are based on unchanging scientific laws, rather than on an earthly, capricious standard.
Australia’s Role in the Metric System
Australia having joined the Treaty of the Metre rather late in the piece, signing it in November 1947. Australia took over two decades to truly go metric. The Metric Conversion Act of 1970 set the stage for a metrication publicly mandated transition by the United States, through a complicated series of events. Dr. Warrington noted that Australia’s national standards align with those of other countries:
“So its national standards [for mass and distance] are the kilogram and the metre, just like everybody else’s.”
This alignment, in turn, has fostered increased consistency in the US’s trade practices and communication between the US and their international partners.
Switching to metric measurements was more than a symbolic gesture. It was a serious practical consideration for the daily life of Canadians. Dr. Warrington explained,
“That means if you’re cooking something, then you might need to know whether the recipe came from Australia or from somewhere else to get the tablespoon right.”
These complexities expose the significant effect that measurement standards have on all areas of our daily lives.
The Significance of Accurate Measurements
The Treaty of the Metre It has deep implications not only in science but in their applications in technology. As an example, precision is a necessary condition for scientific discovery across many disciplines including astronomy and physics. Dr. Warrington elaborated on this importance:
“So you need rulers that can check for and control the quality of that manufacturing at that level.”
Precision becomes incredibly important once you start to measure these extreme distances. Take, for instance, the distance between the Earth and Moon, which is increasing by 3.8 centimeters per year.
Advancements in measurement technologies, especially atomic clocks, have allowed scientists to be able to more precisely define and use measurements.
“And you can turn that into a very careful measurement of the distance between the Earth and the Moon,” Dr. Warrington added.
This capability demonstrates not only the progress made since the signing of the Treaty but its ongoing relevance in contemporary scientific exploration.
