Encyclopedia of popular science knowledge: "Time Knowledge"

Chapter 9 Time's Fun Story (2)
Prawns are also called "prawns" because of their large and fat bodies.When it is fresh, its body is quite transparent, so it is also called "prawn".Prawns do not live together in pairs, but when they are sold, the price is often calculated in units of one pair, hence the name.

The male and female prawns seldom communicate with each other at ordinary times, and they live in one side separately, withdrawn by nature.Every autumn, the juvenile shrimp has grown as fat and strong as the female shrimp, and the gonads of the female shrimp have also matured.At this time, a male shrimp seems to be aware of the existence of the opposite sex, so he slowly swims towards the female shrimp. After a few minutes of circling, chasing, and ejaculating, the mating is completed and the two immediately break up.

In winter, the sunshine is short, the cold winter wind blows hard, the water temperature in the Bohai Sea drops sharply, and the living environment becomes extremely unfavorable for prawns.They gather together, and because of the water temperature, they migrate toward the warm southern sea, which is called seasonal migration.

In the spring of the following year, the seawater temperature gradually rose, and those prawns that spent the winter in the southern part of the Yellow Sea began to lay eggs and reproduce, making a new migration back to their hometown.This is called reproductive migration.

In early March, prawns came to the waters near Shidao in the southeast of the Shandong Peninsula and gathered in large numbers. In early April, swarms of prawns passed through the waters near Weihai, Yantai, and Penglai, and headed for the Bohai Sea. Some of them turned to the south of the Shandong Peninsula and the coast of Jiangsu, and some swam to the Liaodong Peninsula and the Korean Peninsula.

At the end of April, the main group of prawns entering the Bohai Bay will disperse after reaching the outlets of the Yellow River, Haihe River and Liaohe River, and each go to find a suitable spawning place.The shallow sea here has high water temperature and sufficient food, which is conducive to the spawning, reproduction and growth of prawns.After the juvenile shrimp grow up, they migrate to the southern part of the Yellow Sea in autumn to survive the winter.

It's quite a feat for prawns to complete their honeymoon trips of more than 2000 kilometers in a few months of the year.

Crabs live in caves by the water during the day and come out at night to look for food among aquatic plants and gravels. Crabs molt several times in their life. wedding makeup".

In autumn, crabs that mature in fresh water climb to the big river leading to the sea and gather together. They climb and swim against the flow of the river water, advancing about 10 kilometers every day. There is a fierce "fight" for the female crab, and the "couple" is captured.The male and female crabs mate, and the female crab enters the shallow sea. The female crab "holds" the eggs and drills into the seabed sand, waiting for the eggs to hatch.In the spring of the second year, the crab larvae hatched from the eggs look like water silkworms, not at all like their parents.They leave the female crab and develop and grow in the sea. After several molts, they finally turn into crab seedlings slightly larger than mung beans.

Crab seedlings are small and delicate, and they will not only be devastated by strong winds and waves, but also swallowed by many marine animals. Although there are a large number of crabs, there are not many that can really grow into juvenile crabs and survive.

When the tide comes in summer, crab seedlings gather on the sea surface and go up the river with the tide. When the tide ebbs, they crawl on the bottom of the river and wait for the next high tide before moving on.They traveled day and night, collectively "traveling", and then disbanded. They returned to the rivers and lakes where their parents lived to develop and grow, and began to live in caves again.

Crabs grow up in rivers and lakes, put on "wedding makeup", and then go to spend the most wonderful, strange and interesting "honeymoon trip" in their lives.This is the case every year, from generation to generation.

The "summer and winter clothes" of animals The body color of some temperate animals changes constantly with the changes of seasons and environments. They usually change their hair twice a year: summer hair and winter hair.

After the intense breeding period, the birds lose a lot of feathers, and then enter the natural molt period.When birds moult, the old feathers fall off one after another and new feathers grow, and the moulting of the two wings is very regular.It starts from the first wing feather close to the shaft feather, and the left and right wing feathers are replaced symmetrically in order to maintain the balance of the bird's body when flying.During this period, the birds fly less and often hide in the dark grass and bushes to avoid the attack of natural enemies.

In autumn, birds generally begin to moult naturally, the old feathers gradually fall off, and new feathers grow, which are thick and dense. With winter feathers, it is easy to survive the winter.In the spring, the birds moult again, put on thin and sparse new feathers - "summer clothes", ready to lay eggs and reproduce.

There is a kind of ptarmigan near the Arctic Circle. It changes its plumage with the seasons, which is different from birds that change their feathers twice a year. It is a protective color to adapt to the environment and has become a typical example of animal evolution and natural selection.

In winter, except for the black on the top of the head and the outside of the tail feathers, Thunderbird puts on a set of white "winter clothes", and even puts on a pair of white "socks" on its feet.When spring arrives, it embroiders brown and yellow spots on the white feather's "coat", singing sweet songs, and busy with mating.Soon, it changed into a bark-colored "summer dress" and hatched eggs.In the season of bleak autumn wind and falling leaves, it wears dark red "autumn clothes" with big black spots on it.Thunderbirds are often hunted by owls, foxes, and wolves in the vast tundra due to lack of defense capabilities, but they survived with their special protective colors.This is a magical force of natural selection.

In the cold winter, snow weasels, snow hares, ermines, etc. living in the north put on thick winter fur and are completely white, matching the white snow and ice covered by the earth.But in spring and summer, it is replaced with sparse brownish-yellow or taupe summer hair.

Why do the coat colors of these animals change?This is due to the fact that the fur of animals contains a variety of pigments.Winter is coming, the temperature is very low, the food is very scarce, and the light exposure is decreasing, which changes the metabolism of the animal. The nutrients in the blood are not enough to distribute to the end of the hair, and cannot continue to turn into pigment.

The fur color of animals turns white. After the pigment in the feathers disappears, many tiny air bubbles are filled inside.

Animal feathers turn white, which is a kind of mimicry and a protective color to adapt to the environment.

The ermines in the forests of Northeast my country have taupe fur in summer and white in winter.In this way, they are not easy to be found by wild animals when they are active on the snow, and the color change is to protect themselves.

However, the coat colors of polar bears, silver foxes, white eagles, and snow owls in the Arctic are snow white almost all the year round.This may be because white bears and others wear "silver clothes" and are easy to approach and prey on prey, but the important thing is that the white fur surrounds the body, which can reflect back the heat emitted from the body, reduce the emission of body temperature, and play a role in heat preservation. effect.

Sika deer molt twice a year.In autumn, they take off their "summer clothes" and put on new "winter clothes". On the smoky down, the white spots are blurred due to the reduction of white pigment, which can not only resist the cold, but also adapt to the new environment.When spring comes, sika deer shed their winter long hair and put on a "summer dress": on the short chestnut red hair, due to the increase of white pigment, white plum blossom patterns are revealed, so as to meet the needs of summer.

Why does bamboo have no annual rings?

During the period from spring to summer, the cells of the cambium in the bark increase rapidly; during the period from autumn to winter, the increase of cells slows down.Therefore, the part of the plant that grows between spring and summer is softer and thicker; the part that grows between autumn and winter is narrower and harder.As the tree grows thicker each year, annual rings are formed in this way.

But bamboo is different. Bamboo can grow for many years, but its stems will no longer grow thick once they come out of the ground. No matter how old they are, they can only grow so thick.

This is because bamboo is a monocotyledon, while most trees are dicotyledonous.The structure of the monocot stem is very different from that of the dicotyledon. The main difference is that there is no cambium in the stem of the monocot.

Dicotyledonous plants sandwich a thin cambium between the phloem and xylem.The cambium is the most active, and it undergoes cell division every year to produce new phloem and xylem, so the stem grows thicker year by year.However, there is no active cambium between the phloem and xylem of monocots. Therefore, the stems of monocots can only grow thick when they start to grow, and will not grow thick after a certain degree.Therefore, bamboo cannot form annual rings.

In addition to bamboo, wheat, rice, sorghum, corn, etc. are all monocots.Therefore, they also have no annual rings.

Sleeping for 200 million years
People have known for a long time that many creatures in nature have the instinct of hibernation. They can sleep soundly for a long time in harsh environments, and once the environment is favorable for them, they can wake up as before.Some insects, when the environment they inhabit become very dry, will lose water themselves, change their original shape and appearance, and shrink into a small ball, making it difficult to guess whether it is still alive; but if you give it a little Water, when the water penetrates into its body, it will slowly stretch out its body again, returning to the shape before it dries up, and then start to move, look for food, and devour it greedily.

The existing observational data prove that some small insects can go through a dormant state for decades.It's not the longest record, though.People have discovered that the seeds of some plants can still germinate, grow, and bloom after being buried underground for thousands of years.

For example, in Shenyang, Beijing, Hebei and other places in our country, many ancient lotus seeds from more than 1000 to 2000 years ago have been found. After careful cultivation by scientists, all of them have bloomed gorgeous flowers.Some single-cell organisms have a longer survival ability than plant seeds. For example, Canadian scientists have discovered bacteria that have been dormant for 1000 million years in a rock salt layer as deep as 3.2 meters.

What is even more surprising is that some multicellular higher organisms can sleep for a long time, which is unbelievable.The famous scientist Franklin once reported that in the suburbs of Paris, he witnessed quarry workers dig out four live toads from the limestone formed 100 million years ago.Also, in a quarry in New Mexico, USA, once, when workers were excavating rocks, they found a frog in a rock hole exposed by a rock crack.Its skin was tender and shiny, and it could move a few times, and it took two days before it died.According to research, the frog may have hibernated in the hole before the rock was formed.Later, due to some changes, it was sealed in the cave for a long time, and fell asleep without feeling the change of the outside climate.According to measurements, it has slept for about 200 million years!

The origin of the countdown
1969年7月16日上午9时30分（美国东部时间），美国在肯尼迪宇宙飞行中心发射了“阿波罗”11号飞船。发射准备工作在紧张地进行，离发射的时间越来越近，时钟嘀嗒嘀嗒地走着，人们的心情也跟着越来越紧迫，突然从扩音器里传出总指挥下达最后10秒钟的准备发射的口令，同时在控制中心的巨大荧光屏上显示出10、9、8、7、6、5、4、3、2、1，发射！
Immediately, under the launch pad, flames blazed and smoke billowed. With the loud noise that shook the sky, the rocket slowly rose with a long yellow tongue of flame... "Apollo" 11 spacecraft took Armstrong, Alder Lin and Collins, three astronauts, on July 3, the lunar module "Eagle" landed safely in the Tranquility area of ​​the moon. Six hours later, Armstrong stepped out of the lunar hatch in a space suit, turned on the TV camera, and staggered down the escalator. Humans finally set foot on the surface of the moon!He said wittily: "That's one small step for a man, but one giant leap for mankind." Then, Aldrin also set foot on the moon, and they left human beings on the moon. first footprint.They did many meaningful scientific experiments on the moon, collected many samples of lunar rocks, walked on the moon for two and a half hours, and returned to Earth on July 7.

The above-mentioned method of counting in reverse order and displaying the time value in reverse order is called countdown timer. The launch of modern rockets and missiles, the detonation of nuclear devices, etc., all use this countdown timer launch program.

Why count down?This has a history.Since the invention of airplanes, people have tried every means to create higher-speed airplanes and at the same time speed up the development of rockets. In 1926, the world's first liquid rocket was successfully tested in the suburbs of Auburn, Massachusetts, USA.Soon, Germany published a magazine "Spaceship Voyage". The first issue had a spaceship orbiting the earth on the cover, and it was titled "A circle around the earth in an hour and a half!" The space sci-fi feature film - "Girls in the Moon Palace", hired rocket expert Oberth as a technical consultant to manufacture a rocket to provide filming. In order to enhance the dramatic effect of the film, the director Fritz Lange designed a countdown timer launch in the rocket launch shot The program is 10, 9... 3, 2, 1, launch!
This kind of launch procedure has aroused the interest of rocket experts. After research, it is very suitable for rocket launch procedure, and it is very scientific.It is simple, clear, precise, focused and creates a sense of urgency.Therefore, the countdown program is widely used.

missing time
It took Magellan and his successors nearly three years to complete the first voyage around the world.When they were rejoicing when they set foot on the coast of Spain, they found a strange thing: it was clearly written on the nautical diary that this day was September 3, 1522, but it was September 9, 6 on the Spanish calendar. day.

What's going on here?Is time missing?Everyone can't figure it out.People blamed the crew and said: "You are stunned by the stormy sea, and even the day is wrong."

One day missing is not a big deal, but to a religious person, it becomes a great sin.The priest blamed the sailors: "You have misremembered the day, celebrated the wrong festival, and eaten meat on the day when you should be fasting." But the sailors knew that every day they passed, the sailing diary always recorded the major events of the day, and it was logical You can't be wrong, there is really nothing to say.No way, they had to go to the church to confess and ask God for forgiveness.They were wronged for nothing, and they couldn't figure out how this day disappeared until they died.

At the same time, after the opening of the American continent, Europeans came to North America one after another, and they gradually migrated westward from the Atlantic coast to the Pacific coast. At the end of the 18th century, the Russians also crossed the Bering Strait from Asia and came to North America.They lived together and became familiar with each other, and there were often disputes between yesterday and today. The British and French said, "Today is Sunday", but the Russians said flatly that it was "yesterday" and "today" should be Monday. .The people of Britain and France are welcoming New Year's Eve, and the Russians are celebrating New Year's Day.

These two mysteries about the disappearance of time were spread. At the end of the 19th century, Kiinfeev of the Irkutsk Post Office near Lake Baikal in Russia knew about it and was ready to reveal its mystery.

He recorded the local time of the world's major cities on the globe, and then used the desk lamp as the sun, and pointed Irkutsk at the "sun". At this time, Irkutsk should be noon; and New York is located opposite the earth. On the surface, it should be midnight; Chicago is west of New York, separated by 150 degrees of longitude, and it should be 11 o'clock in the evening.

Kienfeev fiddled with the globe, turning left and right, thinking, thinking, puzzled.The next day, he sent a telegram: "America, Chicago Postmaster, I would like to inform you of the date and time of receipt of the call. The return fee has been paid. Irkutsk Post Office Kiinfeev."

这份电报是伊尔库次克当地时间9月1日早晨7点钟发出的。当天，芝加哥的回电来了，“8月31日9时28分接来电。”

How can there be such a thing! ?It was "yesterday" in the United States, and the call back was sent "in advance"!

Days are lost one day, where is the secret of this missing time?It turns out that the earth keeps rotating from west to east, and the sun rises in the east and sets in the west.When Magellan and his party sailed westward around the world, they were chasing the setting sun every day, so night always came later.It took them 1024 days to go around the earth, and if they lost one day, if they were distributed evenly, each day would only be extended by more than one minute, which would not be easy to detect.Conversely, if people sail eastwards around the earth for one week, they will have one more day.

This is also the reason for the one-day difference between the Russians and the British and French.

Unlike Magellan's round-the-world voyage, the British and French came to North America from east to west, while the Russians came to North America from west to east, and they completed another round-the-world voyage together.

The Magical International Date Line
The Chukchi Peninsula in eastern Asia, Fiji, Tonga and New Zealand in the Pacific Ocean are the first places in the world to start a new day, and people celebrate New Year's Day first.The last people in the world to celebrate New Year's Day are the Western Samoans on the east side of the date line. When they first welcomed New Year's Day, Fiji and other countries began to celebrate January 1, with a difference of exactly one day and one night.

Waiyevo, the central town of Tafouni Island in Fiji, just crosses the date line.During the British rule, Christian regulations did not allow shops to open on Sundays, requiring people to go to church to worship.There is a merchant in the town named Vania, whose shop is just across the dateline.He purposely opened the back door.He usually operates at the front door; on Sundays, he operates at the back door.Because it's already Monday at the back door.By repeating this, he can always avoid the prohibition of business on Sunday.

Nuku'alofa, the capital of Tonga, advertises itself as "the place where the sun first rises in the world".There are luxurious hotels in the city called "dateline hotel" to attract tourists.In fact, Nuku'alofa is located at 175°20' west longitude, and should belong to West District 1. It can also be called "the westernmost capital in the world".In order to avoid dividing the country by the date line, it was included in the East 12th District.

Apia, the capital of Western Samoa, is located at west longitude 171°41′. It originally belonged to West District 11. After the adjustment, the date line was moved to the west of Apia.Arguably it was the last to see the sun sink below the horizon.

(End of this chapter)