Our perception of time has always been a central part of human existence, yet its nature and meaning continue to fascinate and challenge us. From ancient civilizations that measured the passage of time by the position of the sun to modern theories in physics exploring the relativity of time, we have always strived to understand this abstract dimension. Even though time can be interpreted in many ways — and remains a hotly debated topic among theorists — one thing is certain: humans depend on it. Below, you’ll find ten facts about time that you may not have known before!
1 Time moves faster the higher up you go…
Because of the theory of relativity, time passes more slowly the closer you are to Earth’s core. This means that your head is technically younger than your feet, and if you want to live longer, you should consider moving to Mount Everest. A year is about 15 microseconds shorter at the summit than at sea level. [source]
2 A second is not one-sixtieth of a minute…
Since 1967, the International Committee for Weights and Measures has defined a second as “the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom“. It can also be measured as a fraction of a year — 1/31,556,925.9747 of a year, to be exact. However, a second has been used as 1/60 of a minute since the Babylonians in 300 BC. [source]
3 Dinosaurs had more days in their years than we do…
Because of the drag created by the Moon’s gravitational pull, Earth’s days have been getting shorter for over a billion years. While a current year is 364 days, 56 minutes, and 4 seconds long, the year at the time when dinosaurs went extinct was around 370 days long. And during the Cambrian explosion — 542 million years ago, when most modern animal phyla first evolved — a year was roughly 420 days long. [source]
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4 Time really does seem to move faster as you get older…
When older people say that everything feels like it goes by so quickly, they’re actually right in a way. Because of a psychological phenomenon known as the “oddball effect”, time appears to speed up as you age, since experiences become more familiar and stand out less from your past. [source]
5 The oldest objects on Earth are fake diamonds…
Australia’s remote Jack Hills are the source of the oldest known objects on Earth — flakes of zircon crystals estimated to be about 4.4 billion years old. Traces of biological material were found on some of these zircons and dated to 4.1 billion years ago, suggesting that life emerged on the planet shortly after Earth formed. Although they should not be confused with cubic zirconia — a completely different material — colorless zircons have also been used as diamond substitutes because of their hardness and clarity. [source]
6 The world’s most accurate clock would theoretically keep working even after the end of Earth…
The strontium clock, developed in 2015, is the most accurate clock in the world, measuring the vibrations of super-cooled strontium atoms with ultra-powerful lasers. It is so precise that lifting it just two centimeters off the ground would create a measurable difference. And if it were left untouched forever, it wouldn’t be off by even a single second for the next 15 billion years.
Unfortunately, Earth won’t be around that long — by then, the Sun will have long since expanded into a red giant. [source]
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7 We don’t just have leap days — we also have leap seconds…
To help synchronize atomic clocks with Earth’s actual rotation — which is very gradually slowing down — leap seconds are occasionally added to the 24-hour day. A total of 26 leap seconds have been added since the first one in 1972.
This doesn’t mean all our days are now half a minute longer — only the specific days that include a leap second were one second longer. The most recent one was in June 2015. [source]
8 Time travel is plausible, but not possible — or is it the other way around…?
Scientists continue to theorize about the possibility and feasibility of time travel or traveling faster than light. A few years ago, researchers at CERN believed they had measured subatomic particles moving faster than the speed of light, but it later turned out to be nothing more than an instrument error. Wormholes might be a potential way to travel across vast distances faster than light, but there is still no definitive evidence that they actually exist.
Astronomer Frank Tipler came up with an idea to essentially build a gigantic tube in which you would place a piece of matter ten times the mass of the Sun. If you could make it spin at several billion rotations per minute, anything moving in a precise spiral around the cylinder could end up in a loop that takes it back to the point where it started spinning. Unfortunately, the tube would need to be infinitely long.
Even if you could travel back in time, the universe would likely balance out any action you take — meaning that if you killed Adolf Hitler as a child, another “Adolf Hitler” would simply appear to take his place. Confusing, right? And keep in mind that all of this is just theory — at least for now! [source]
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9 It took 1,500 years and a pope to get the calendar back on track…
Early Christians adopted the Julian calendar, assuming that every year was 365.25 days long. However, this is about 10–11 minutes too long. Those extra minutes began to accumulate, and by the 1500s the calendar was off by more than an entire week. The spring equinox was tied to Easter, and over the centuries, these two events had drifted farther and farther apart.
In 1563, the Council of Trent, under Pope Gregory XIII, prepared a plan to add days to the calendar to correct the synchronization issues, and in 1582, ten days were added. It took centuries before the Gregorian calendar became widely adopted. [source]
10 China is almost as geographically large as the U.S. — but has only one time zone…
While China historically used multiple time zones, Chairman Mao declared in 1949 that the entire country would follow Beijing Time for the sake of national unity. This means that in the far-western Xinjiang region, the sun can set around midnight or rise at 10:00 a.m.
What complicates things even further is that the region’s largest ethnic minority follows its own local time, which is two hours behind Beijing Time. Most of China’s population lives in the eastern part of the country, and for them, having a single time zone is seen as a minor inconvenience. [source]
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5 Common Questions About Time
Time is often defined as the continuous progression of events from the past to the present and into the future. In physics, time is considered a dimension—just like height, width, and depth—used to measure change.
This is largely due to a psychological effect known as the “oddball effect“, which causes new or unique experiences to feel longer. As we age, life becomes more routine, and fewer new memories make time feel like it’s speeding up.
According to Einstein’s theory of relativity, time travel to the future is theoretically possible by traveling at extremely high speeds or experiencing intense gravity. However, travel to the past has no proven mechanism and remains purely theoretical.
Leap years exist because Earth’s orbit takes about 365.242 days, not an even 365. To stay in sync with the seasons, we add an extra day every four years. Leap seconds are added occasionally because Earth’s rotation is gradually slowing, helping atomic clocks stay aligned with the planet.
Most countries use the Gregorian calendar and standardized time zones, but there are exceptions. For example, China uses one single time zone despite its huge size, and some regions use half-hour or even 45-minute offsets instead of full-hour zones.
