from: Every Single Second
by Tricia Springstubb
illustrations by Diana Sudyka
Balzer + Bray/HarperCollins, 2016
Since Stonehenge and the Egyptian pyramids, and probably earlier than that, people have been measuring time. From grains of sand falling through an hourglass to the precision of a Swiss watch, we mark the momentous occasions and trivial pursuits of our lives by noting seconds, minutes, and hours.
Being more and more precise about time measurement has been a goal for many scientists. The first atomic clock was invented in 1949 by Isidor Rabi, a physics professor at Columbia University. He showed that measuring the vibrations of an ammonia molecule would produce an accurate measurement of time. His discovery has been improved on through the years, and since 1999, the National Institute of Standards and Technology (NIST), uses an atomic clock that measures the frequency of the element cesium. The clock is accurate to about one second in 100 million years. https://www.timeanddate.com/time/how-do-atomic-clocks-work.html
But as the saying goes, time is relative. When I asked about that, my mom described her understanding of Einstein’s theory of relativity. If you touch a lit match, a second seems like it will never end. But, when you watch a sunset, minutes pass without giving time a thought. I’m sure there’s lots more to it, but that definition worked for me. Actually, it still does.
And ten years into the future always seems longer than ten years ago. When I wonder where I’ll be in ten years (assuming I’m still alive!) it kinda seems like forever from now, but looking back at the last ten feels like a blink. So in my mind, time is fluid.
Turns out, time really is kinda fluid. While it takes our Earth 24 hours to rotate on its axis as we orbit the sun causing day and night, that varies from day to day. OK, only by a fraction of a second, but scientists around the world have noticed that Earth instead of trending slower, has been spinning faster lately, faster, in fact, that ever before.
Up until now, one complete rotation has taken a little longer than 24 hours (about 86,400.002 instead of 24 hours x 3,600 = 86,400). Twenty-seven seconds have been added to our clocks since 1972, about 1 second every year and a half.
Called a leap second, it is added periodically, either on December 31, or June 30, to keep our clocks synchronized with the time it takes for Earth to complete one rotation on its axis. The last one was added on December 31, 2016. Here’s a chart: https://www.timeanddate.com/time/leapseconds.html
Earth’s 28 fastest days since 1960, all occurred in 2020. https://www.pennlive.com/nation-world/2021/01/earth-is-spinning-its-fastest-in-decades-heres-how-scientists-are-addressing-the-issue.html Scientists have discovered many reasons for the fluctuation, including the pull of the moon, snowfall levels, and mountain erosion. As the snow caps and high-altitude snow continues to melt, some planetary scientists wonder how much of an impact global warming will have on Earth’s spin.
The Antarctic ice sheet is the largest single mass of ice on Earth. It is made of 30 million cubic kilometers of ice: about 30 quadrillion tons of material. It’s located between 8000 and 9000 feet (2400-2700 meters) above sea level. Every time some of that ice melts or calves into the ocean, it not only causes sea levels to rise, it redistributes Earth’s mass so that it’s closer to the central rotational axis. And just as a figure skater can control her rate of spin by raising and lowering her arms, fluctuations in Earth’s rate of spin change according to how much mass is located closer to Earth’s center of gravity. So the changes in ice and water storage on Earth may be responsible for both the current speed-up in Earth’s day, as well as newly observed wobbles in Earth’s rotation. https://www.forbes.com/sites/startswithabang/2021/01/07/why-does-the-spinning-earth-speed-up-if-the-tides-are-slowing-us-down/?sh=7c851f0b343e
A leap second was scheduled for December 2020, but was not added. If the speed-up continues, some scientists predict we may need a negative leap second.
So while 2020 seemed like the longest year ever, it was anticipation that made it feel that way. Waiting for an end to the pandemic, the end to a political crisis, the end to this non-normal lifestyle, I didn’t notice Earth moving a little quicker than usual, skipping almost a whole second.
I guess time really is relative.
Mom taught me to live in the moment. We can’t change the past. We can only plan and hope for the future. It is here, right now, this moment that is always becoming the past, that is meaningful. We are allowed a finite number of seconds to live on Earth. We don’t know how many. We may even get an extra one now and then.
Do, contemplate, relax. Most important, though? Pay attention to as much as you can.
-—stay curious! (and aware)