Time to Let Go of the Leap Second?
Why timekeepers may stop adjusting our clocks to match the Earth's spin.
Written for any C1 learner. Adapt it to make it about your student: their level, their work, their goals.
Introduction
Have you ever thought about how we keep time? For centuries, our clocks were based on the Earth's rotation, but now we use extremely precise atomic clocks. Sometimes these two ways of measuring time drift apart, and we add a 'leap second' to bring them back in line. This week, the world's timekeepers are voting on whether to stop doing that. Before we read, think: have you ever noticed a time adjustment, like daylight saving, and wondered why we do it?
Key Vocabulary
9 wordsLearn these words before reading the article. They will help you understand the text better.
drift out of sync
to gradually become no longer matching or happening at the same time
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headache
a problem or situation that causes difficulty or worry
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for good
permanently; forever
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cutting a link
ending a connection or relationship between two things
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lived experience
the knowledge and understanding gained from actually living through something
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celestial navigation
the method of finding your position by observing the sun, moon, stars, or planets
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gravitational pull
the force of attraction between objects with mass
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infrastructure
the basic systems and services that a society or organization needs to function
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unchanging
staying the same; not changing
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Article
Read the article carefully. Take your time to understand the main ideas.
Listen to the article. The sentence being read is highlighted; click any word to hear it.
For most of history, humans have measured time by watching the sun and stars. A day was simply the time it took for the Earth to spin once on its axis. But in the 20th century, scientists developed atomic clocks that are far more accurate than our planet's rotation. These clocks count time based on the vibrations of caesium atoms, and they are now the foundation of everything from GPS navigation to global financial networks.
The trouble is that the Earth does not spin at a perfectly constant rate. The gravitational pull of the Moon, ocean currents, and even melting glaciers can cause tiny changes in the length of a day. Over long periods, the planet is gradually slowing down, but in recent years it has actually been speeding up slightly. This means that the precise time kept by atomic clocks, known as Coordinated Universal Time or UTC, can drift out of sync with the natural day.
To fix this, timekeepers have occasionally inserted an extra second into our clocks, a so-called leap second. Since 1972, this has been done 27 times, most recently at the end of 2016. The leap second keeps our official time roughly in line with the position of the sun in the sky, which matters for astronomers and anyone who uses celestial navigation.
But leap seconds have become a headache in the digital age. Computer systems often assume that time moves forward smoothly and that every minute has exactly 60 seconds. When a leap second is added, some software crashes because it is not prepared for a minute with 61 seconds, or for time to jump backwards. In the past, major websites and internet infrastructure have gone down during leap second events.
Now, delegates from around the world are meeting near Versailles, France, to vote on whether to abandon the leap second for good. If they agree, the practice would be retired by 2035, and any future correction would be much larger, perhaps a leap hour that would not be needed for centuries. Supporters of the change say it would make timekeeping simpler and more reliable for modern technology. Critics argue that we would be cutting a link between our clocks and the natural world, and that future generations might find it strange that noon no longer matches the sun's highest point.
A Question of Precision and Philosophy
Some experts point out that the leap second is not just a technical issue. It touches on a deeper question: should our measurement of time be based on the unchanging laws of physics, or on the rhythms of our own planet? Atomic time is incredibly stable, but the Earth's rotation is part of our lived experience. For now, the vote is expected to pass, but the debate is likely to continue among scientists, engineers, and philosophers.
Comprehension Questions
Answer these questions to check your understanding of the article.
- 1What is the main reason the article gives for why leap seconds have become problematic in recent years?
- 2According to the article, what has caused the Earth's rotation to speed up in recent years?
- 3What does the phrase 'cutting a link' suggest about the critics' view of abandoning the leap second?
- 4Why might a negative leap second be particularly risky, according to the article?
- 5What can be inferred about the relationship between atomic time and the Earth's rotation from the article?
- 6How does the article present the philosophical objection to ending leap seconds without taking a side?
Further Discussion
Discuss these questions about the topic and your personal experiences.
- 1What are the potential consequences of disconnecting official time from the Earth's rotation? Consider both practical and philosophical aspects.
- 2Who stands to gain the most from ending the leap second, and who might lose something? Think about different industries and groups.
- 3Some argue that the leap second is an outdated concept in a digital world. Do you agree? Why or why not?
- 4If you were a delegate at the Versailles meeting, what arguments would you make for or against the proposal?
- 5The article mentions that a leap hour might be needed in the distant future. What challenges might that pose for future societies?
- 6Argue for the side you disagree with: either defend keeping leap seconds or advocate for their abolition, presenting the strongest case you can.
Wrap-up & Reflection
In this lesson, we explored the debate over the leap second, a small adjustment that has big implications for technology and our connection to the natural world. We practiced vocabulary related to time, precision, and change, and discussed the trade-offs involved. For reflection, think about a time when a small change in a system caused unexpected problems. How did people adapt? Write a short paragraph about it, using at least three of the new words or phrases from this lesson.
Make it about your student
Same story, rewritten at your student's level, with discussion questions about their job, goals and weak spots. The vocabulary stays from the news, so they learn words outside their usual topics.
Sources
LinguaFlow wrote this article for language learners from facts reported by the sources below. Read them for the full story.