The metric system conquered nearly every aspect of measurement—length, weight, volume, temperature. But there's one domain where it failed spectacularly: time. Despite multiple attempts over two centuries, decimal time has never gained lasting acceptance, and the reasons reveal fascinating insights about human psychology and the nature of time itself.
French Revolutionary Time (1793-1805):
• 10 hours per day
• 100 minutes per hour
• 100 seconds per minute
Modern Proposals:
• 100 centidays per day
• 1000 millidays per day
• Various decimal subdivisions
The most famous attempt at metric time occurred during the French Revolution. Along with their decimal calendar, the revolutionaries introduced decimal time in 1793. The day was divided into 10 hours, each hour into 100 minutes, and each minute into 100 seconds.
Special decimal clocks were manufactured showing both traditional and revolutionary time. The system was officially mandated for all public clocks in France, and watchmakers were required to produce decimal timepieces.
But unlike the metric system for weights and measures, decimal time was a disaster from the start:
Practical problems: A decimal hour lasted 2.4 traditional hours—far too long for practical use. People couldn't adapt to such unnatural divisions of their day.
International isolation: While France used decimal time, the rest of the world continued with traditional hours. This made scheduling international activities impossible.
Worker resistance: Laborers found the system confusing and unnatural. Traditional time divisions had evolved to match human biological rhythms and work patterns.
• Biological rhythms: Human circadian cycles don't align with decimal divisions
• Cultural entrenchment: Time divisions are deeply embedded in language and culture
• Astronomical basis: Traditional time reflects natural cycles (day/night, seasons)
• International coordination: Time must be globally synchronized to be useful
The French quietly abandoned decimal time in 1805, though the decimal calendar persisted until 1806. Napoleon, ever practical, reportedly said that changing people's relationship with time was more difficult than conquering nations.
But why did metric measurements succeed while metric time failed? The differences are revealing:
Metric measurements solved real problems: The old systems of weights and measures were chaotic, with different regions using different standards. Metric provided clarity and consistency.
Time wasn't broken: The 24-hour day, 60-minute hour system worked well. It had evolved over millennia to match human needs and astronomical observations.
Natural foundations: Traditional time divisions have astronomical and biological bases. The 24-hour day reflects Earth's rotation. The roughly 30-day month approximates lunar cycles.
Cultural integration: Time divisions are embedded in language, religion, and culture in ways that weights and measures aren't. We say "quarter past" and "half past" because these fractions feel natural.
Modern attempts at time reform have been equally unsuccessful:
Swatch Internet Time (1998): Swatch proposed dividing the day into 1000 "beats" with no time zones. Despite marketing efforts, it gained no traction outside of novelty use.
Decimal time proposals: Various scientists and efficiency experts have proposed decimal time systems, but none have gained serious consideration.
Computer time: Even computers, which excel at decimal calculations, use traditional time internally (though they often convert to seconds for calculations).
The failure of metric time reveals something profound about the nature of time measurement:
Time is experiential: Unlike length or weight, time is something we experience directly. We have intuitive feelings about how long an hour or minute should be.
Time is social: Timekeeping is fundamentally about coordination with others. Any time system must be widely adopted to be useful.
Time is ancient: Our time divisions have roots going back to ancient Babylon and Egypt. This gives them a cultural weight that newer systems can't match.
Interestingly, some aspects of decimal time do exist in specialized contexts:
• Scientific calculations often use decimal fractions of days
• Some computer systems use decimal time internally
• Astronomical calculations frequently use decimal days
• Some industrial processes use decimal time for efficiency
The 60-minute hour and 24-hour day have proven remarkably resilient. They survived the fall of empires, the rise of science, and the digital revolution. Even as we've decimalized nearly every other measurement, time remains stubbornly traditional.
This persistence isn't just cultural inertia—it reflects the deep connection between time measurement and human experience. The traditional divisions of time evolved to match our biological rhythms, work patterns, and social needs in ways that purely mathematical systems cannot.
The failure of metric time teaches us that not all measurements are created equal. While standardization and decimal systems work well for physical quantities, time is different. It's not just a measurement—it's the framework within which we live our lives.
Today, as we use atomic clocks and GPS satellites to measure time with unprecedented precision, we still divide our days into the same hours and minutes that ancient civilizations used. The metric system may have conquered space, but time remains unconquered—and perhaps unconquerable.