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Daily Maverick
19-05-2025
- Science
- Daily Maverick
150 years ago, the Metre Convention determined how we measure the world — a radical initiative for the time
150 years ago, the world agreed to a shared language of measurement. It still holds us together, even when everything else seems to pull us apart. On May 20, 1875, delegates from a group of 17 countries gathered in Paris to sign what may be the most overlooked yet globally influential treaty in history: the Metre Convention. At a time when different countries (and even different cities defined weights and lengths based on local artefacts, royal body parts or grains of wheat, this rare agreement among nations offered something simple yet undeniably impactful: consistency. A radical initiative for its time, the Metre Convention ultimately birthed a system of measurement that would transcend language, politics and tradition, and lay the foundation for a new global era of scientific and technological advancement. A world divided by measurement By the mid-19th century, the push for standardisation had become increasingly urgent. Scientific discovery was accelerating, global trade was booming and industrial projects were growing in scale and complexity. But the world's measurements were, frankly, a mess. France had introduced the metric system during its revolutionary years, but other nations were slow — or outright unwilling — to adopt it. Rivalries simmered not just among empires, but within the scientific community itself. Astronomers couldn't compare celestial observations across borders because their units didn't match. Engineers designing railway systems across Europe had to navigate conflicting standards for track gauges, load weights and even timekeeping. This wasn't just inefficient. It was a barrier to progress, a strain on economies and a growing source of frustration or a scientific world that aimed to speak in universal truths. Faced with growing societal demands, the industrial world agreed it was time to act. The Metre Convention was the result. Scientists and diplomats representing the 17 participating countries collectively established the Bureau International des Poids et Mesures (BIPM), headquartered just outside Paris, as the official keeper of measurement standards. Today, the BIPM is backed by 64 member states and governs the Système International d'Unités (SI), the measurement framework that underpins everything from bridges to smartphones. When standards fail And while by today's standards, the SI may seem like a relic of old-school science bureaucracy, it's anything but. Standardised measurement is the invisible infrastructure of the modern world. And when it fails, or more specifically when we ignore it, the consequences can be severe. Take the Gimli Glider incident: In 1983, an Air Canada flight from Montréal to Edmonton ran out of fuel midway through its journey. The cause was a miscalculation caused by confusion between metric and imperial units; the ground crew had used pounds instead of kilograms to measure fuel, and the pilots didn't catch the error. The plane lost power at 41,000 feet (around 12,500 metres for those who prefer their near-death experiences in metric), and glided safely to an abandoned airstrip in Gimli, Man., and to the annals of history as a symbol of what happens when we take standards for granted. Or consider the Mars Climate Orbiter, a US$327 million NASA spacecraft that disintegrated upon entering Mars' atmosphere in 1999. Engineers at Lockheed Martin had used imperial units, while NASA had assumed metric. The mismatch led to a critical navigation error and the failure of the mission, highlighting the importance of consistency in measurement, even far beyond the confines of Earth's atmosphere. The Gimli Glider and Mars Orbiter failures show what happens when consistency breaks down, but they're more than just cautionary tales. They reveal how much of modern life depends on the shared language of measurement, and how easily that foundation can be cracked. And therein lies the genius of the Metre Convention. It created a system that allows the world to communicate in the same terms. When someone says 'kilogram,' 'second' or 'volt,' there is no ambiguity. That shared understanding is what makes global collaboration possible. From man-made objects to universal constants For much of its post-Metre Convention history, the kilogram was defined by a physical artefact — a hunk of platinum-iridium alloy stored in a vault in France. But in 2019, that changed. Now, the kilogram is defined by Planck's constant, a fundamental feature of the universe. The shift marked the final step in a long journey: every base unit in the SI is now rooted in nature rather than arbitrary human artefacts. That change wasn't just symbolic, it was necessary. Our ability to measure time, mass and distance with extreme precision affects nearly every aspect of modern life. GPS signals rely on time measurements accurate to the billionth of a second. Quantum computers and particle accelerators require calibration on mind-bendingly small scales. Even weather forecasting depends on standardised measurements of pressure, temperature and humidity. Shared standards in a divided world But perhaps the most underrated legacy of the Metre Convention is its role in building trust across borders. At a time when misinformation spreads quickly and even basic facts are contested, international standards offer a shared foundation that scientists, governments and industries can rely on. It's a form of global co-operation that has quietly endured for 150 years. That co-operation becomes particularly apparent in moments of political strain. Although the United States appears uncompromising in its commitment to feet and inches, American scientists, engineers and manufacturers rely heavily on the metric system, especially when collaborating across borders. As tensions rise between close allies like the US and Canada, metric standards remain a consistent point of harmony. The two countries may spar diplomatically, but when it comes to assembling a car in Windsor with parts made in Detroit, the bolts still fit. Looking ahead Still, like all institutions, BIPM and the SI reflect the times in which they were created. The original signatories were almost exclusively colonial powers. It took almost a century for other nations to gain an equal seat at the table, and even now, access to the tools and infrastructure that facilitate precision metrology — the act of taking extremely accurate measurements — remains unequal. If the next 150 years of the Metre Convention are to be as successful as the first, greater inclusivity and accessibility will need to be central to its mission. We live in a world held together by decimals, tolerances and agreed-upon constants that keep planes in the air, bridges from collapsing and scientific progress on track. The Metre Convention reminds us that science isn't only about big breakthroughs and bold ideas. Sometimes it's about consensus and agreeing, together, on what a metre actually is. And even after 150 years, the simple idea of agreeing how to measure the world remains one of humanity's greatest achievements. So, what should we do with this anniversary? Maybe throw a party with metric-themed cocktails (may I suggest a 100ml Old Fashioned?). At the very least, we should take a moment to reflect on just how essential, and how easy to overlook, measurement really is. DM
Washington Post
17-05-2025
- Science
- Washington Post
NIST set its new atomic clock in motion, and it's astoundingly precise
A new atomic clock is one of the world's best timekeepers, researchers say — and after years of development, the 'fountain'-style clock is now in use helping keep official U.S. time. Known as NIST-F4, the clock is at the Boulder, Colorado, campus of the National Institute of Standards and Technology (NIST). The clock relies on cesium atoms, which oscillate between quantum states at a frequency of over 9 billion times per second. NIST-F4 uses lasers to cool a ball of cesium atoms to near absolute zero, then measures the frequency of the atoms as they pass through a microwave chamber. As they rise and fall like water in a fountain, the atoms oscillate, 'ticking' more than 9 billion times per second. The length of that second is so reliable that the clock would be off by less than a second if it had started running 100 million years ago, researchers say. In an article in Metrologia evaluating the clock's accuracy, researchers say the clock is accurate enough to help calibrate coordinated universal time (UTC). It took months to assess the super-precise clock, its inventors say. All that testing was worth it: The agency 'has already benefited significantly from the fountain's high uptime and the reliability of its performance,' Liz Donley, chief of NIST's time and frequency division, said in a news release. Once certified by the International Bureau of Weights and Measures (BIPM), NIST-F4 will become one of a small cadre of clocks used to calibrate coordinated universal time. It's already in use as part of the agency's UTC(NIST) timescale, which provides official time for the United States.
Yahoo
04-05-2025
- Science
- Yahoo
US scientists debut atomic clock that stays true for 100 million years straight
Marvel's Time Variance Authority (TVA) would probably call dibs on this atomic clock if they could! The NIST-F4 atomic clock, recently unveiled by the National Institute of Standards and Technology in Boulder, Colorado, is one of the most accurate timekeeping devices ever built on Earth. This clock is so precise that if it had started ticking during the age of the dinosaurs, it would still be accurate today to within a single second. This month, NIST scientists officially submitted it to the International Bureau of Weights and Measures (BIPM) for certification as a 'primary frequency standard,' a title reserved for the most elite atomic clocks on the planet. Only around ten countries operate such clocks — now the U.S. is back in that top tier. Unlike regular clocks, atomic clocks like NIST-F4 keep time using the natural vibrations of atoms — in this case, cesium atoms. Inside the clock, thousands of these atoms are cooled to near absolute zero using lasers and then tossed upward in a fountain-like motion. As they rise and fall, they pass through microwave radiation tuned to a frequency that makes the atoms shift their energy state — a transition that defines the "tick" of the clock. That tick happens precisely 9,192,631,770 times per second, and counting those ticks is how the clock defines the official second. "Fountain clocks are supposed to be very boring," said Greg Hoth, a physicist on the NIST team. In this case, boring means reliable, and that's exactly what global systems depend on. Time isn't just about watches and alarms — it powers everything from GPS to stock market trades to data centers. 'Time signals are used literally billions of times each day for everything from setting clocks and watches to ensuring the accurate time stamping of hundreds of billions of dollars of electronic financial transactions,' said Liz Donley, who leads NIST's Time and Frequency Division. NIST-F4 helps steer the official U.S. time scale, known as UTC(NIST), and contributes to the global timekeeping standard, Coordinated Universal Time (UTC). Its ultra-precise data helps ensure systems worldwide stay synchronized down to the microsecond. NIST-F4 didn't happen overnight. It evolved from NIST-F1, the agency's first fountain clock built in the late 1990s. After a move in 2016 disrupted F1's performance, NIST scientists decided to rebuild the heart of the clock — the microwave cavity — from scratch. They spent years refining every part, from magnetic coils to optical systems, achieving tolerances as fine as one-fifth the width of a human hair. "Evaluating a fountain clock... is a slow process because we have to be very conservative,' said physicist Vladislav Gerginov. NIST has already submitted NIST-F4's data to the BIPM for formal certification. Meanwhile, it runs alongside NIST-F3 to ensure that at least one fountain clock is operating at all times. 'The success of NIST-F4 has renewed NIST's global leadership in primary frequency standards,' Donley said. And until optical clocks eventually redefine the second, cesium-based fountains like this one will keep global time ticking perfectly.
