It takes 24 hours for the earth to rotate once, which is a basic common sense. Although this length of time is artificially specified, depending on the selection of the reference frame, the actual length of a day will not deviate too much. However, what people think of as a day is more based on the sun as a reference.

Earth's day shortened by less than 24 hours

Such a solar day does not seem to be much different from the actual rotation time of the earth. However, due to some factors, the rotation speed of the earth will change, resulting in a day that is not exactly 24 hours. Scientists have discovered that the Earth's rotation has accelerated a bit in recent years.

In 2020, the increase in rotation speed is even more significant, and the time of day is less than 24 hours. People may not feel any change in the time of day, because the time difference is very small, and the shortest day is only reduced by about 1.46 milliseconds. Human beings cannot directly feel such a time difference. To detect such a small time difference, a very accurate clock is naturally required.

The accuracy of the cesium atomic clock has reached an extremely high level before, with an error of only 1 second in 180 million years. However, when used to measure events in the microscopic field such as atomic vibrations, the more accurate the clock, the more the error can be reduced. The newly developed optical lattice clock has a greater improvement in accuracy, and it only takes 1 second in 15 billion years error.

Human activities have caused the earth to spin faster

To measure the cycle of celestial bodies, atomic clocks are sufficient to meet the accuracy requirements. For ordinary people, even if the time of day is shortened by one minute, it will not have any big impact. The acceleration or deceleration of the earth's rotation is a very slow process, and it takes a long time to accumulate before there will be a large time difference change.

Biological evolution on the earth has experienced greater changes in a day's time. Therefore, the time on the earth is less than 24 hours a day, which will not affect the routine of living things. So what does the timing of changes have a big impact on? The time change at the millisecond level seems insignificant, but in some equipment scenarios that rely on precise timing, such as satellite communications, it will bring about the impact of time mismatch and may cause malfunctions.

And the method to eliminate this time difference is also very simple, that is, to regularly adjust the clock time of the whole world. By adding or subtracting 1 second, the world's clocks are kept in a normal synchronized rhythm. Scientists predict that the earth's rotation speed will continue to accelerate, which means that the time of the earth's day will be further reduced.

The reason is that human activities have played a major role in promoting it. Human activities have caused global warming to intensify. The glaciers in the Arctic and Antarctic continue to melt, and sea levels have risen partly. The melting glaciers were originally located higher, and after melting, the center of gravity moved down, causing the volume of the earth to shrink a bit.

Changes in the time of day on the earth will not affect the regularity of living things

According to the principle of conservation of angular momentum, when the average radius of the earth decreases, the rotation speed will become faster. It can be seen from this that in the early days of the earth, the ocean area was larger, the average radius was smaller, and the rotation speed was very fast. However, this change in rotational speed that occurs with changes in the distribution of matter on the earth's surface is not the main factor affecting the rotational speed of the earth.

The gravitational force between the moon and the earth has a greater effect on the angular momentum of the earth. The gravity of the moon causes tides on the earth, and the friction caused by the tides reduces the rotation speed of the earth, so that the moon gradually moves away from the earth.

As the moon moves further away, the Earth's rotation speed decreases in the process, and the day lengthens significantly. But such a change will not occur in a short period of time. In the case of the shortening of the day, adjusting the time in time will not have a major impact.

The habits of organisms can change with the change of the environment. In the past, the earth only had a dozen hours a day, and species continued to survive and reproduce. However, the time change in a short period of time is only a few seconds, and such a time difference is almost negligible. As humans migrate to Mars, the concept of time established will also be different. Adapting to that time change is inevitable.