Gravitational force, on the other hand, is a universal force between all forms of energy or mass.

It cannot be confined to the membrane, instead, it has to permeate the entire space. Because gravity is not only dissipative, but also dissipates in large quantities into additional dimensions, it should decay more with distance than electricity.

The electricity is confined to the membrane. However, we know from observations of planetary orbits that the gravitational pull of the Sun decreases as the planet moves farther away from the Sun, in the same way that electricity decreases with distance.

Thus, if we do live on a membrane, there must be some reason why the gravitational pull does not spread far away from the membrane, but is confined to its vicinity.

One possibility is that the extra dimension ends on the second shadow membrane, which is not far from the membrane in which we live.

We can't see this shadow film because light can only travel along the membrane and not through the space between the two membranes. However, we can feel the gravitational pull of objects on the shadow film. There may be shadow galaxies, shadow stars, and even shadow people, who may be greatly surprised by the gravitational pull from the matter on our membranes.

For us, this kind of shadow object appears as dark matter, which is invisible matter. But its gravitational pull can be felt.

In fact, we have evidence of dark matter in our own galaxy. The total amount of matter we can see is not enough for gravity to hold the rotating galaxies together. Unless there is some kind of dark matter, the galaxy will scatter.

Similarly, the total amount of matter we observe in galaxy clusters is not enough to prevent them from scattering, so that dark matter must be present.

Of course, shadow film is not necessary for dark matter. Dark matter may be nothing more than some form of matter that is difficult to observe, such as WIMP (weakly interacting heavy particles), or brown dwarfs and low-mass stars, which are never hot enough to burn hydrogen.

Because gravity diverges into the region between our membrane and the shadow membrane, the gravitational force between two neighboring objects on our membrane decreases more with distance than electricity, because the latter is confined to the membrane. We might be in a laboratory using an instrument invented by Sir Cavendish in Cambridge to measure the short-range behavior of gravity.

So far we have not seen any difference with electricity, which means that the distance between the membranes cannot exceed one centimeter. This is tiny by astronomical standards, but it is huge compared to the upper bound of other extra dimensions. New measurements of gravitational force at short distances are being made to test the concept of a "membrane world".

Gravitational force can bend space and therefore propagate to extra dimensions (e.g., a primary function is linear but described by two unknowns), and by moving through imaginary time in a parallel universe, it can travel through time through gravity.

24 (36) regions of the Earth's surface divided by meridians. When we see the sun rising on the sea, it takes another half an hour for those who live in Kasingpo to see the sun rise. The residents of the Cinnamom are still asleep and will not see the sun for another eight hours.

People around the world live and work in their own local areas, which can cause a lot of inconvenience and difficulties in daily life and transportation.

In order to take care of the convenience of each region, it is easy for people in other places to convert local time to other places.

The international conference decided to divide the Earth's surface into zones from east to west according to the meridians, and to stipulate a time difference of one hour between adjacent areas.

People at the eastern and western ends of the same area see the sun rise at most than 1 hour.

When people cross an area, they correct their clocks by 1 hour (minus 1 hour to the west and add 1 hour to the east), and add or subtract a few hours when they cross several areas.

This makes it easy to use. Today, the world is divided into 24 time zones. Since it is often practical for a country or province to span two or more time zones at the same time, a country or a province is often grouped together for administrative convenience.

Therefore, the time zone is not strictly divided according to the straight line of north and south, but according to natural conditions. For example, Huaxia is a vast country that spans almost five time zones, but in fact only the standard time of the eighth time zone in the east is used, i.e., the imperial capital time.

Zone Time: A type of time measured by a globally harmonized system of time zones. Whenever the sun shines on your head, it's 12 o'clock in the afternoon.

But the time it takes to see the sun as a headlight is different in different places. For example, when it is 12 noon at sea, it will take five hours for the residents of Scomo to see the sun in their heads; And it was already 2 o'clock in the afternoon for the Nissos of Greater Asia.

Therefore, if the local time standard is used in each locality, it will cause a lot of inconvenience to administrative management, transportation, and daily life.

In order to overcome this difficulty, astronomers have come up with a solution: to divide the world's longitude every 15 degrees apart, so that there are a total of 24 regions.

A uniform time standard is applied within each region, known as "zone time". The difference in zone time in adjacent areas is 1 hour. When people travel east from one area to an adjacent area, they set their clocks forward by one hour, and after walking through several areas, they set them up by a few hours.

Conversely, when people travel west from one area to an adjacent area, they slow down their clocks by one hour and several hours after walking through several areas. In transportation centers such as airports, the districts corresponding to major cities in the world are often shown on maps for the convenience of passengers.

Huaxia Time Zone (Republic of China Period)

There are five time zones in China:

1. Central Plains Time Zone: 120 degrees east longitude is the central meridian.

2. Shu time zone: 105 degrees east longitude is the central meridian.

3. Tibetan area: 90 degrees east longitude is the central meridian.

4. Kunlun time zone: 75 (82.5) degrees east longitude is the central meridian.

5. Changbai time zone: 135 (127.5) degrees east longitude is the central meridian.

After 1949, the imperial capital time was used instead.

The timing system is the working system that determines and broadcasts the precise time. At the hour, the radio listening to the radio will broadcast a "beep, beep, ......" sound, which is used to correct the speed of their clocks.

Where does the correct time come from on the radio station? It is controlled by the Observatory's sophisticated clock. So how does the observatory know these precise times? We know that the earth rotates evenly once a day, and as a result, the stars in the sky rise in the east and set in the west once a day.

If you think of the earth as a big clock. The stars in the sky are like the numbers on the clock face that represent the hour. Astronomers have determined the position of the stars very well, which means that the number of hours on the face of this natural clock is known with precision. An astronomer's telescope is like a pointer on a clock face.

In the clock we use every day, the hand turns and the clock face does not move, here it seems that the hand is "not moving" and the "clock face" is turning. When the stars are aligned with the telescope, astronomers know the correct time and use this time to correct the observatory's clock.

This allows astronomers to know the correct time from the clock face of the observatory at all times. Then at a certain time every day, for example, on the hour, by radio broadcast, we can go and proofread our clocks, or for other work.

Astronomical time measurement relies on the rotation of the earth, and the unevenness of the earth's rotation makes the time (world time) accuracy obtained by astronomical methods only reach 10-9, which cannot meet the needs of all aspects of social economy in the mid-twentieth century. A more accurate and stable standard of time was born, and this was the "atomic clock".

Countries around the world use atomic clocks to generate and maintain standard time, which is the "time reference", and then, through a variety of means and media to deliver time signals to users, including: short-wave, long-wave, telephone network, Internet, satellite, etc. This entire process is called the "timing system".

It refers to the hour, which is divided into 12 hours a day in ancient times, and uses the earthly branch as the name of the hour, and has an ancient customary name.

The beginning of the hour is midnight. Gu Yanwu's "Daily Knowledge": "From the Han Dynasty below. The calendar gradually became denser, so the day was divided into 12 hours, and I don't know who it started with, and it has not been abolished so far...... However, it (referring to Du Yuankai's note) said that the middle of the night is the so-called sub-time of today, the rooster is ugly, the flat is Yin, the sunrise is Mao, the food time is Chen, the corner is also, the middle of the day is noon, the sun is not also, the feeding time is Shen, the day is in, the day is in, the dusk is also, and the person is fixed. The day is divided into twelve, and it is seen here. ”

In the Northern Song Dynasty, each hour was divided into two parts: "beginning" and "zheng", and the twelve hours were divided into twenty-four, which were called "hours".

carve

About before the Western Zhou Dynasty, the ancients divided the day and night into 100 quarters, and carved 100 squares on the shaft of the leaky pot. Converted into modern chronometric units, 1 quarter is equal to 14 minutes and 24 seconds. The "100-engraved system" is the oldest and longest-used timekeeping system in China.

In the Han Dynasty, while using the "100 carving system", the "solar azimuth timing" method was used to measure the length of the sun's projection with a gui watch to judge the time.

The table is composed of two parts: one is a benchmark or stone pillar that measures the shadow of the sun standing upright on the flat ground, called a watch; One is a stereotype for measuring the length of the shadow in the direction of due south and north, which is called Gui. Since the shadow of the sun can be measured in units of length, there is a saying that "an inch of time is an inch of gold". Each position of the sun measured by the watch gradually has a fixed name, which is the origin of the hour.

In the Sui and Tang dynasties, the "sun azimuth timekeeping" officially evolved into "twelve hour timekeeping". The "100-hour system" and "12-hour timing" were used together, which made the ancient Chinese timekeeping system tend to be perfect.

At the end of the Ming Dynasty and the beginning of the Qing Dynasty, Western mechanical clocks were introduced to China, and the 12 hours were used at the same time, as well as the 24-hour timekeeping method of the day. Since the 100-tick system is not divisible by 12 hours, it is difficult to calculate, so it was changed to 96 ticks, 108 ticks and 120 ticks. It was not until the Qing Dynasty that the day and night were officially stipulated as 96 quarters, and each hour was eight quarters, which were divided into the upper four quarters and the lower four quarters.

Novels often have the saying "open at three o'clock in the afternoon", such as the ninth chapter of "Journey to the West": "But it is said that Prime Minister Wei Zheng is in the house, watching the dry elephant at night, and he is only smelling the nine cranes, but he is a heavenly immortal envoy, holding the Jade Emperor's golden decree, and he dreams of slashing the old dragon of Jinghe at three o'clock in the afternoon." ”

At three o'clock in the afternoon, according to the method of timing, there is a difference of fifteen minutes to 12 noon.

According to the Yin-Yang family, Yang Qi is at its peak at this time, while modern astronomy believes that noon is the most prosperous, and the two are slightly different. Three o'clock in the afternoon is the time when the ancient felons were beheaded, at this time, the knife is beheaded, the yang energy is the most vigorous, and the yin energy will dissipate immediately after death, and the criminals who commit the most heinous crimes are "not even allowed to do ghosts" after being beheaded, in order to show severe punishment. If the punishment is light, the knife can be cut at noon, and the ghost will do it. Therefore, "at three o'clock in the afternoon, I dreamed of cutting the old dragon of Jinghe" to show that the old dragon committed a very serious crime.

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The staff on duty in the palace of the Han Dynasty were divided into five shifts and replaced on time, called "five watches", so that the night was divided into five watches, and each shift was an hour. It is a watch, a second watch, a third watch, a fourth watch, and a fifth watch, and its correspondence is as follows:

Day of the first watch: 19:00-21:00

Second watch: 21:00-23:00

Three watches: 23:00-01:00 sub-time

Fourth watch: 01:00-03:00 when ugly

Fifth watch: 03:00-05:00

"Drum horns" and "bells and drums" are all instruments used to beat the watch in ancient times.

dot

In ancient times, copper kettles were used to time the leakage, and the following leakage points were named. A watch is divided into five points, so the length of one point is 24 minutes. For example, "Journey to the West: Chapter 9: "But it is said that after Taizong woke up from a dream, he thought about it in his heart." It had already reached five drums and three o'clock, and Taizong set up a dynasty and gathered two classes of civil and military officials. "Three watches and two o'clock" refers to 11:48 p.m.; "Five drums and three o'clock" refers to 04:12 in the morning.