24 incredible facts about time
- Did you know that a day on Earth used to be about six hours shorter than it is today? Or that Julius Caesar once introduced a 445-day year? You will find out these and other interesting facts about time in this list.
1. Every person on Earth lives in the past.
This may seem like the plot of a fantasy thriller about time travel, but it is actually a fact of human biology and the insidiousness of time. Our brain perceives events only 80 milliseconds after they happen. This thin line between present and past is one of the reasons why some physicists argue that there is no such thing as "now" and that the present moment is nothing more than an illusion.
2. Throughout history, different cultures around the world have had different perceptions of time.
In the Western world, people tend to think of time as linear and flowing from left to right. But this is not the case for everyone. Language influences how people think of time, especially the spatial metaphors they use to describe and display it.
Those who read in languages where time flows from right to left, such as Arabic and Hebrew, usually perceive time as flowing in the same direction. The Aymara, who live in the Andean mountains of South America, believe that the future is behind them and the past is ahead. According to them, since the future is unknown, it is behind you where you cannot see it.
Some Indigenous Australian cultures, whose languages make extensive use of concepts such as north, south, east and west, represent the passage of time as moving from east to west. For example, if they are facing north, then the past will be on their right, or in the east, and the future will be on their left, that is, in the west.
3. Individuals can also perceive time differently.
You've probably noticed how time speeds up when you're having fun, and how it drags on when you're bored. This is because when you're focused on something, like a big work project or a party, your brain pays less attention to how time passes. But when you're bored, or your brain is less stimulated, you begin to notice the passage of time better, causing it to seem slower.
One study suggested that dopamine—a neurotransmitter and hormone that helps us feel happy—may be an additional culprit. It showed that the increased production of dopamine that occurs when you enjoy something can slow down your body's internal clock, making it seem like time is flying by.
4. There are many different ways to determine time in science.
Here are just a few: There is astronomical time, which is measured by how long it takes the Earth to rotate on its axis. In astronomical time, a second is equal to 1/60 of a minute. And then comes atomic time, which dictates the numbers you see on the clock. According to atomic time, one second is equal to 9,192,631,770 vibrations of a cesium-133 atom. Measuring the vibration of an atom - which, in simple terms, is the essence of vibration - is the most accurate way to keep track of time.
5. We can thank Albert Einstein for much of our current understanding of the physics of time.
Instead of viewing time as a set order, he proved that it is in fact relative. For example, according to Einstein's theory of special relativity, there is an inverse relationship between your speed and the speed of time. The faster you move, the slower time moves.
Here's why a person flying through space will age more slowly than people still located on Earth: Astronaut Scott Kelly was born a few minutes after his twin brother Mark, but after Scott spent 340 days on the International Space Station, he returned to Earth about 5 milliseconds younger than his "older" brother. If Scott were flying at close to the speed of light, this age difference would be much more noticeable.
6. Einstein's theory also states that gravity can bend time.
If you've watched the 2014 movie Interstellar, this concept may sound familiar to you. The closer you are to a massive body - and in the case of Interstellar, it's a giant black hole - the slower time passes for you.
7. The influence of gravity on time is not limited to intergalactic travel.
Here on Earth, gravity can change for a number of reasons, including altitude, as you change the distance from the center of the Earth. This means that if you put a bunch of synchronized atomic clocks at different altitudes, eventually those clocks will get out of sync. The clocks at the top of Everest and the clocks at sea level over the entire 4.5 billion years of the planet's history would have diverged by about a day and a half.
8. Gravity is also the reason why our days are getting longer.
More than a billion years ago, a day on Earth lasted about 18 hours. Our days are now longer because the moon's gravity is slowing the earth's rotation. In early times, the Moon was not that far from the Earth, so the Earth rotated much faster than it does now.
Longer days also mean shorter years. The time it takes the Earth to orbit the Sun hasn't changed, but the number of days in a year has. When dinosaurs lived 70 million years ago, the day was only 23.5 hours long, and the year consisted of 372 of these shorter days.
9. Since astronomical time and atomic time do not always coincide, we occasionally get a leap second.
The speed of the Earth's rotation can be a bit unpredictable. Atmospheric winds, Northern Hemisphere winters with heavy snowfalls, and other major weather systems can affect the planet's rotation rate. To ensure that the difference between astronomical and atomic time does not exceed 0.9 seconds, the International Earth Rotation and Reference Systems Service announces the need to introduce a leap second from time to time.
Most people don't notice leap seconds, but they can be a big problem for tech companies. Since leap seconds are not added regularly, there is no way for developers to include them in their codes, which has caused crashes on sites like LinkedIn and Reddit in the past. A bug caused by the 2012 leap second caused such chaos on Qantas' servers that more than 400 flights were delayed.
10. The length of a year on Earth can also be a little tricky.
The original Roman calendar was so confusing that Julius Caesar introduced a 445-day year in 46 BC to bring the calendar into line with the seasons.
11. At the same time, Caesar asked the astronomer Sosigenes to help reform the calendar.
Most years were set at 365 days, but to compensate for the fact that the Earth's revolution around the Sun does not take exactly 365 days, leap years were introduced. Every four years, the month of February received an extra day to compensate for a rounding error in the calendar.
12. But Sosigenes miscalculated a bit, so the calendar continued to deviate a little.
He believed that the year lasts 365.25 days. In fact, it lasts 365 days, 5 hours, 48 minutes and 45 seconds, which equates to approximately 365.242 days. This tiny mistake had some pretty serious consequences: by 1577, the Julian calendar was off by 10 days, which meant major Christian holidays were celebrated on the wrong dates.
Pope Gregory XIII took note of this and set up a commission to get the calendar back on track. The Gregorian calendar was created in 1582. Instead of having an extra day every four years without exception, years that are multiples of 100, such as 1700 or 1900, skip a leap year. Unless the year is divisible by 400, like 2000, in which case it's a leap year again! However, even this system is not perfect: it has an error of one day in 3236 years.
13. We can thank the rail industry for standardizing time zones.
Until the 19th century, towns and villages synchronized their clocks with the local solar noon. This led to thousands of local clocks, all of which were different and made scheduling transport a pain in the ass. Train timetables in different cities had to contain dozens of arrival and departure times for each train to accommodate all mini-time zones.
On November 18, 1883, railroad companies in the US and Canada began using a system very similar to the standardized time zones we still use today. In Britain, railway companies began using London Standard Time in 1840.
14. After an engineer named Sandford Fleming missed his train in 1876, he decided to change how time worked.
Fleming originally proposed a concept he called "Cosmic Time" in which the world would run on an imaginary clock located at the center of the planet, essentially a line from the center of the planet to the Sun. He then proposed dividing the world into 24 time zones, designated by letters of the alphabet, each spanning 15 degrees of longitude.
His original plan for a standard "cosmic time" was abandoned, but he laid the foundation for a similar standardization, the so-called universal time. And the nations attending the International Meridian Conference in 1884 laid the groundwork for dividing the world into 24 time zones, with the Prime Meridian, also known as Longitude 0°, running through Greenwich, England.
15. Even with the advent of standardized time, people still struggled to keep their clocks in sync.
One London family used this to their advantage and made a living by selling people time. An astronomer named John Belville set his pocket watch to the time at the Royal Observatory in Greenwich. He then traveled around the city and visited his subscribers, who paid to have their watches set to Belleville pocket watches.
After Belleville's death in 1856, his wife and later their daughter Ruth continued the tradition. Ruth continued to sell time well into World War II. By then she was in her eighties, and several factors led to her timely retirement: improvements in technology made her role less important, and the war made trekking around London too dangerous.
16. The sundial shows different readings depending on which hemisphere you are in.
In the Northern Hemisphere, the sun casts a shadow that moves from north to east, from east to south, from south to west. In the Southern Hemisphere, the shadow moves in the opposite direction. Our notion of "hour hand" is based on how sundials in the Northern Hemisphere told time.
17. Time zones can still be a little tricky.
Major countries like Canada and the US have multiple time zones, while China, the other major country, has only one. China has adopted Beijing Standard Time to promote unity, but the effect may seem a bit strange - two cities in a country can be at roughly the same latitude but sunrise occurs at different hours. For example, in some parts of China, the sun rises only at 10 am.
18. Although many people believe that daylight savings time was adopted to keep farmers happy, this is a myth.
The first person to seriously advocate daylight saving time was an entomologist who wanted to have more hours of sunshine to look for insects after working in summer. He proposed his idea to the scientific society in New Zealand in 1895.
19. Daylight savings time was officially introduced only in 1916.
Germany became the first country to switch to it in order to save coal during the First World War. The United States only followed suit in 1918.
20. After the war, daylight saving time ended at the national level, but individual states and municipalities continued to implement it until World War II.
After the end of the First World War, the entire country switched to year-round daylight saving time. After World War II, the whole country again chose and decided about daylight saving time. In Iowa in 1964, it was reported that there were 23 different combinations of dates when communities switched to daylight saving time and back. In 1966, the government officially established standard daylight saving time for the entire United States, although individual states could choose not to.
Until 2007, daylight saving time ended in October. It was reported that the candy industry lobbied for the idea of setting the clock back an hour after Halloween.
21. Daylight Saving Time doesn't just make people lose an hour of sleep.
In fact, it can have some pretty serious health consequences. Research has linked daylight saving time to an increase in heart attacks, car accidents, and injuries in the mining industry. However, the extra hour of daylight is good for koalas. Researchers found that during the transition to daylight saving time, the number of collisions of koalas with cars is reduced by 11%.
22. People have been keeping track of time for thousands of years.
In 2013, while excavating a field in Scotland, archaeologists discovered what is believed to be the world's oldest lunar calendar. The calendar, consisting of 12 pits imitating the phases of the moon, dates back to around 8000 BC.
23. The most accurate clock is at the National Institute of Standards and Technology in Boulder, Colorado.
The clock tells time by measuring the vibration of a single aluminum ion and should remain accurate for 33 billion years. The clock on your bedside table is not as accurate.
24. The new clock is set to 10:10 for a reason.
If you recently bought a new clock or watch, you may have noticed that it is set to 10:10 by default, give or take a few minutes. There are various theories explaining this timing, but it really comes down to aesthetics. Setting the time around 10:10 allows the analog watch hands to display neatly, symmetrically without obscuring the logos in the center of the dial. The clock was once set to 8:20, and sometimes still is, but the downward pointing hands can give the impression that the clock is frowning.