What does the French Revolution have to do with the time NASA accidentally crashed a $200 million orbiter into the surface of Mars? Actually, everything. That crash happened due to an error in converting between two measurement systems, U.S. customary units and their S.I, or metric, equivalence. So what's the connection to the French Revolution? Let's explain. For the majority of recorded human history, units like the weight of a grain or the length of a hand weren't exact and varied from place to place. And different regions didn't just use varying measurements. They had completely different number systems as well. By the late Middle Ages, the Hindu-Arabic decimal system mostly replaced Roman numerals and fractions in Europe, but efforts by scholars like John Wilkins to promote standard decimal-based measures were less successful. With a quarter million different units in France alone, any widespread change would require massive disruption. And in 1789, that disruption came. The leaders of the French Revolution didn't just overthrow the monarchy. They sought to completely transform society according to the rational principles of the Enlightenment. When the new government took power, the Academy of Sciences convened to reform the system of measurements. Old standards based on arbitrary authority or local traditions were replaced with mathematical and natural relationships. For example, the meter, from the Greek word for measure, was defined as 1/10,000,000 between the Equator and North Pole. And the new metric system was, in the words of the Marquis de Condorcet, "For all people, for all time." Standardizing measurements had political advantages for the Revolutionaries as well. Nobles could no longer manipulate local units to extract more rent from commoners, while the government could collect taxes more efficiently. And switching to a new Republican Calendar with ten-day weeks reduced church power by eliminating Sundays. Adoption of this new system wasn't easy. In fact, it was a bit of a mess. At first, people used new units alongside old ones, and the Republican Calendar was eventually abandoned. When Napoléon Bonaparte took power, he allowed small businesses to use traditional measurements redefined in metric terms. But the metric system remained standard for formal use, and it spread across the continent, along with France's borders. While Napoléon's empire lasted eight years, its legacy endured far longer. Some European countries reverted to old measurements upon independence. Others realized the value of standardization in an age of international trade. After Portugal and the Netherlands switched to metric voluntarily, other nations followed, with colonial empires spreading the system around the world. As France's main rival, Britain had resisted revolutionary ideas and retained its traditional units. But over the next two centuries, the British Empire slowly transitioned, first approving the metric system as an optional alternative before gradually making it offical. However, this switch came too late for thirteen former colonies that had already gained independence. The United States of America stuck with the English units of its colonial past and today remains one of only three countries which haven't fully embraced the metric system. Despite constant initiatives for metrication, many Americans consider units like feet and pounds more intuitive. And ironically, some regard the once revolutionary metric system as a symbol of global conformity. Nevertheless, the metric system is almost universally used in science and medicine, and it continues to evolve according to its original principles. For a long time, standard units were actually defined by carefully maintained physical prototypes. But thanks to improving technology and precision, these objects with limited access and unreliable longevity are now being replaced with standards based on universal constants, like the speed of light. Consistent measurements are such an integral part of our daily lives that it's hard to appreciate what a major accomplishment for humanity they've been. And just as it arose from a political revolution, the metric system remains crucial for the scientific revolutions to come.
法國大革命和美國太空總署 價值兩億美元的人造衛星 意外墜毀於火星表面的事件 有什麼關聯呢? 實際上,息息相關。 那起墜毀事件源自 兩個度量衡之間的轉換錯誤。 從美國慣用單位 轉換為公制單位。 到底它與法國大革命有何關聯呢? 且聽我細說。 自人類有史以來的大部份時間, 單位並不很精確 ──例如穀粒的重量、手的長度── 且因地而異。 不僅各地的度量衡不同, 數字系統也各不相同。 在中世紀後期之前, 印度—阿拉伯的十進制系統 幾乎完全取代歐洲的 羅馬數字和分數; 但是,由約翰·威金斯等學者 所倡導的十進制度量衡 並沒那麼成功。 僅法國一地, 就有 25 萬種不同的單位, 大破大立,需大破才能全面地改革。 大破發生於 1789 年。 法國大革命的領袖不只推翻帝制, 還根據啟蒙運動尊崇理性的原則, 試圖全面改造社會。 新政府掌權後, 科學院召開院會改革度量衡系統。 根據專制威權或地方傳統的舊制, 被具有數學和自然關係的 新制所取代。 例如「公尺」 ──在希臘語是「測量」之意── 被定義為赤道和北極之間 距離的一千萬分之一。 而馬奎斯·孔多塞宣稱 新的公制是「全人類的,永遠的。」 量測標準化對革命者也有政治利益。 貴族再也無法 操縱地方的度量衡單位, 向平民收取更多的租金, 而政府收稅也更有效率了。 使用一星期有 10 天的共和曆, 因去掉星期天而削弱了教會的勢力。 採用新制並不容易。 事實上,搞得有些亂。 一開始,人們採新舊制並用; 後來,共和曆被棄用了。 拿破崙·波拿巴掌權後, 允許小企業使用 以公制重新定義的傳統度量衡。 公制仍是官方正式的度量衡, 隨著法國領土擴張, 散播到整個歐洲大陸。 雖然拿破崙的帝國只歷時八年, 但它的建樹影響得更久遠。 有些歐洲國家在獨立後改回舊制; 其他的則體認到 標準化在國際貿易時代的好處。 在葡萄牙和荷蘭 自願轉換為公制之後, 其他國家紛紛效法; 隨後跟著殖民帝國的勢力, 公制散佈到世界各地。 法國的主要競爭對手英國 抵制這個革新的想法, 仍然使用其傳統的單位。 但在接下來的兩個世紀中, 大英帝國逐漸轉變, 先是允許公制做為替代單位, 慢慢地變成官方正式單位。 但對已獨立的 13 個前殖民地而言, 這個轉換來得太晚了, 美國繼續延用 其殖民時期的英制單位, 是今日世上僅有的三個 尚未全面改為公制的國家之一。 儘管十進制的倡議未曾間斷過, 許多美國人仍認為 用英尺和英鎊比較直觀。 諷刺的是,現在某些人 視過去革命性的公制 為全球一致性的象徵。 儘管如此,公制系統 被普遍用於科學和醫學, 並持續依其最初的原則而進化。 長久以來, 標準單位是依被精心維護的 實體樣品來定義, 由於技術和精確度的改進, 這些不易取用、壽命有限的物體 現已被以通用常數 為依據的標準所取代, 例如光速。 一致的測量是我們日常生活中 不可或缺的一部分, 很難體會到它對人類 有如此大的成果。 公制始於政治革命, 它對未來的科學革命至關重要。