On January 1, 2017, all human beings were forced to renew for 1 second because there were 24 hours and 01 seconds on this day.
this extra second was stuffed to the position at 07:59:60 Beijing time.
This second is also called leap second .
However, just a while ago, foreign technology giants such as Amazon , Microsoft , Meta, Google and other foreign technology giants jointly launched an event, said they would cancel the leap second.
It’s not that they don’t let people live one more second, but because “the side effects of leap seconds have long exceeded their own value.”
Although this proposal has been supported by relevant American institutions, the cancellation of such a big leap second is not the final say of a country.
Today we are simple disks, what can we do in leap seconds, and why we need to cancel it now.
/ Why are there leap seconds?
We have two mainstream time standards before, one is the world of civil use, and the other is the international atomic time used in high-end fields.
World time can also be said to be Greenwich time. Its day length is calculated based on the average rotation period of the earth, and the time point and the sun position are kept in synchronization.
For example, the sun is above the head, it is 12 noon.
But there is a problem in the world. The earth is affected by various factors in climate and crust movement, and the rotation time is different.
In other words, the day in the world is not an eternal 24 hours, and there will be a few milliseconds of error.
These milliseconds have no effect on the World Super League, and it usually ends in a few seconds.
But it is not possible for aerospace, satellite navigation and other fields.
Like satellite positioning , each satellite is constantly transmitting radio signals containing position and time, with accuracy up to within one meter and one billionth of a second.
Even if the error is only 0.1 seconds, multiplying it by the speed of light, the satellite positioning will be a thousand miles away.
So high-end fields use international atomic time timing.
International atomic time is calculated by the atomic oscillation frequency, which can be accurate to nanoseconds . What is the concept of
? my country's latest cesium atomic clock (NIM 6), with an error of no more than 1 second in 54 million years.
Someone may ask, since there are atoms, what do we ordinary people do when we don’t use atoms?
Because the time of the earth rotating around changes, over time, the difference between the position of the sun and the atomic time becomes larger and larger.
10,000 years later, may appear, and nodding at 11 pm, the situation of a big sun being pushed on.
However, there are problems in the world, and it is different in length every day and every second.
So in 1972, we ordinary people used a new standard called Coordinated Universal Time (Coordinated Universal Time for short) .
You can also call it stitching monster.
It uses the timing speed of the atomic time. When the error between the world time reaches 0.9 seconds, it will add and subtract 1 second.
In this way, the time is accurate in normal times, and it will not mismatch the position of the sun over time.
In order to maintain synchronization, the extra or cut-off second is leap seconds. Currently, 27 leap seconds have been added to the world.
/leap second
Although leap second solves the problem of time and earth rotation mismatch, it also brings new troubles.
For example, if we want to add one second, the time will become 23:59:59, 23:59:60, 00:00:00. There is a strange 1 second in the middle of
. It doesn’t matter what you are, that is, you just have to be stunned for one second.
But many servers can't stand it.
Because leap seconds are different from leap years, there is no pattern to follow and cannot be written into the system in advance.
If there is a sudden 1 second extra, many old programs will report various errors if they don’t know how to face it.
For example, in 2012, leap seconds caused large-scale downtime of servers of Reddit, Mozilla, LinkedIn, and Yelp.
The same year A handling system of Australian Airlines also crashed for several hours and was forced to manually check passengers boarding the plane.
2017, the leap second also caused some client servers to be offline in Cloudflare.
There are many reasons for this, let’s briefly talk about one.
Because of adding a second, many tasks will fail to start due to mismatch of conditions. At this time, they will keep trying and looping until the system is blocked.
for example.
There are 60 steps between each floor of a building. The delivery robot will put a bucket of water on every floor of the floor and receive an receipt , indicating that the task is completed.
But at this time, a certain layer had 61 steps, and the robot still went to 60 and put it down directly. As a result, no receipt was received, and then it kept putting it on. Isn’t the problem arise?
In addition, there are some more complex situations that we will not discuss.
Although the system now has certain adaptations for leap seconds, who guarantees that there will be no errors? What’s more important is that next time you don’t have to add 1 second, but you’ll be minus 1 second. This situation has not been encountered yet, so who can guarantee that there will be no new problems?
/ Should leap seconds be cancelled?
Seeing this, you can also understand why these technology giants have cancelled the leap second.
They think that canceling the leap second is actually no big problem after 1,000 years, and it is not much different.
Well, that's right, but descendants may be scolding you, let's throw the problem to them, right?
In fact, as early as more than ten years ago, people have always said that they would cancel the leap second, but many people also opposed it.
" The system crash is obviously because I didn't handle it well, so why are there no problem for others? "
" Leap seconds allow everyone to maintain accurate time, and also allows everyone to rotate with the earth and synchronize with the sun when they are not separated from the world."
has even more sensual reasons for opposition, such as the UK because leap seconds can make time consistent with world time.
World time is Greenwich time, cancels the leap second, and the proud Greenwich time is equivalent to being abandoned.
Royal Observatory of Greenwich, UK
24-hour electronic clock outside the gate ▼
/Is there a better way?
Of course, these technology giants do not want to simply kill leap seconds, but want a better solution.
For example, Meta proposes an solution called Smearing, which is to spread 1 leap second to 17 hours and slowly leap.
Previously, Google was working on a "early leap" solution.
It adds several milliseconds per day to the server clock, so that when adding leap seconds, the adjustment amplitude will not trigger a big problem.
Someone also proposed to replace leap seconds with leap minutes, leap times. It means adding another leap minute for each phase difference of 59 seconds to reduce the adjustment frequency.
But no matter what, I think that no matter whether it is a leap second or an early leap, the mechanism of "leap" must exist.
Because humans’ concept of time comes fundamentally from the sun.
Since ancient times, we have looked up and saw that the sun rose in the east and the sun set in the west is at night.
Working from sunrise and resting from sunset. As long as human life is bound to the sun, it is naturally inseparable from the world.
is just this way to keep in touch with the sun, and this "leap" mechanism may require a better solution.
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