The speed of light in the Milky Way is so great that it takes 100000 years for the light to travel completely.

The speed of light is about 186000 km \ sec. The farthest star we can see with the naked eye is actually looking at the past 4 billion years ago.

It takes a long time for the light from that star to enter your eyes. Average life time to go to the toilet: half a year's life, eating time: three years' life, speaking time: ten years' life, sleeping time: 22 years' life, hair length: 1000 kilometers' life, tears capacity: 65 liters' life, peeling weight: 47.5 kilograms' life, cell count: 750 trillion, walking distance: 22,500 kilometers? I still have a lot of short science knowledge.

Then ask, because I don't have time to input so much popular science knowledge now. My real name is Zuo, thank you.

2. Poor knowledge of popular science

speed of light

The Milky Way is too big for light to pass through completely 100000 years. The speed of light is about 186000 km \ sec. The farthest star we can see with the naked eye is actually looking at the past 4 billion years ago. It takes a long time for the light from that star to enter your eyes.

average life span

Time to go to the toilet in a person's life: six months; Time to eat in one's life: three years.

Life time to speak: ten years. Sleep time in one's life: 22 years.

The growth length of hair in a lifetime: 1000 km The capacity of tears in a lifetime: 65 liters.

Weight of skin desquamation in a lifetime: 47.5 kg. Number of cells produced in a lifetime: 750 trillion.

Lifetime walking distance: 22,500 kilometers

Do you still want to know? I still have a lot of short science knowledge. Then ask, because I don't have time to input so much popular science knowledge now.

My real name is Zuo, thank you.

3. Students who lack popular science knowledge

Small knowledge of science and technology

Plug tip

Why do electric fans, washing machines, refrigerators and other household appliances mostly use three-wire plugs? What is the difference between a three-wire plug and a three-phase plug?

Three-phase electrical appliances refer to three different live wires, and the voltage between each two wires is 380 volts. They are generally used in power systems and are more common in industrial electricity consumption. Single-phase power supply is generally used in household appliances, and its three wires are live wire, neutral wire and ground wire. The voltage between the live wire and the neutral wire is 220 volts, so this is not three-phase electricity, and its plug socket is not a three-phase plug socket. The grounding wire is to ensure safety.

Fruit with antihypertensive effect

Hawthorn; Hawthorn can dilate blood vessels and lower blood pressure and cholesterol. You can choose 10 wild hawthorn (fresh is better), mash it with 30 grams of white sugar, and take it after decocting in water, which has a good effect of lowering blood pressure and invigorating stomach.

Bananas; Bananas contain a variety of vitamins, which can clear away heat and lower blood pressure and can be eaten regularly. It is also effective to decoct with 30~60 grams of banana peel or fruit stalk. Take a proper amount of plantain flowers and take them with water, and the curative effect is better.

Water chestnut; It has the effect of clearing away heat and lowering blood pressure. You can use fresh water chestnut (washed, mud removed) and jellyfish (washed and salt removed) to cook soup three times a day. It can not only lower blood pressure, but also reduce phlegm and relieve cough.

Pineapple basket: Eating pineapple regularly can strengthen the hydrolysis of fibrin in the body, which has a good effect on improving blood circulation and eliminating edema and inflammation in hypertension, edema and thrombosis.

Mume: Rich in citric acid, malic acid and succinic acid. For those with hypertension, dizziness, insomnia, and difficulty sleeping at night, 3 pieces of dark plum and appropriate amount of rock sugar can be stewed in boiling water, which has the functions of lowering blood pressure, sleeping peacefully, clearing away heat and promoting fluid production.

Apple: contains malic acid, citric acid, vitamins A, B, C and other nutrients 10. Eating apples often can improve arteriosclerosis.

Five secrets of drinking milk scientifically

Drinking milk is good for health, but many people still have some conceptual misunderstandings about drinking milk. This article introduces some common sense of drinking milk scientifically.

1. It is not advisable to drink milk on an empty stomach in the morning. Because the gastrointestinal peristalsis is fast when the human body is on an empty stomach, the nutrients in milk often rush into the large intestine before being absorbed. In addition, the method of swallowing milk is not feasible, because it will reduce the chance of mixing with saliva in the mouth, which is not conducive to digestion and absorption. You'd better eat some biscuits, cakes, etc. Before drinking milk, or eating snacks while drinking milk.

Drinking milk at night is more beneficial. Scientific research has found that there is a special law of calcium metabolism in human body: at night, especially at midnight, the plasma calcium content will appear a "trough", forcing the body to transport part of calcium in bones to supplement it through regulation mechanism. Although this temporarily maintains the calcium in the blood, the calcium in the bones is reduced. Milk is rich in calcium. Drinking a glass of milk before going to bed can compensate the body's demand for calcium at night.

Milk should not be cooked with sugar. Milk is rich in amino acids. At high temperature, lysine in milk reacts with sugar to produce a new compound-fructosyl amino acid. This substance can't be digested and absorbed by human body, but it affects human health. It is best to drink fresh milk. If it is too cold, you can heat it a little.

If you don't like milk, you can drink yogurt. Most people who hate milk suffer from lactose intolerance. These people can try to drink yogurt. The lactose content in yogurt is greatly reduced, but almost all the nutrients in milk are retained. Among them, lactic acid bacteria can survive and reproduce in human body, which is beneficial to the absorption and utilization of nutrients and improves immunity. Yogurt contains no antibiotics, is easy to digest and absorb, and can be drunk on an empty stomach.

5. Yogurt can't be heated for drinking. Drinking yogurt is mainly about eating its nutrients and living bacteria. For example, when yogurt is heated, the human body can only drink nutrients but lose bioactive lactic acid bacteria, so don't drink it after heating.

4. Students who lack popular science knowledge

1, pupils should swim under the guidance of adults and learn to swim; 2. Don't play alone by the river or the mountain pond; 3. Don't go swimming in non-swimming areas; 4, can't swim, don't swim to the deep water area, even with a lifebuoy is not safe; 5. Make proper preparations before swimming to prevent cramps;

Second, the self-help method when drowning:

1, don't panic, find someone around you and call for help immediately; 2. Relax your whole body, let your body float on the water, head out of the water, kick the water with your feet to prevent physical loss and wait for rescue; 3. When your body sinks, you can press your palm down; 4. If you suddenly cramp in the water and can't dock, call for help immediately. If there is no one around, you can take a deep breath and dive into the water, straighten your cramped legs and pull your toes up with your hands to relieve cramps.

Three, found someone drowning rescue methods:

Method 1: throw lifebuoys, bamboo poles, wooden boards and other things at the drowning person and drag them to the shore;

Method 2: If there is no rescue equipment, you can enter the water for direct rescue. When approaching a drowning person, turn his hips, turn his back to himself, and then pull him up. Side stroke or backstroke towing is usually used for towing.

Special emphasis: when minors find someone drowning and can't rush into the water to rescue them, they should immediately call for help or use life-saving equipment to call for help.

Fourth, the first aid for drowning people on shore.

1, quickly remove the sludge, weeds and secretions in the mouth and nose, keep the respiratory tract unobstructed, pull out your tongue and avoid blocking the respiratory tract; 2. Lift the drowning child to lie prone on the rescuer's shoulder, with the abdomen close to the rescuer's shoulder and the head and feet drooping, so that the accumulated water in the respiratory tract can naturally flow out. But don't delay the time of cardiopulmonary resuscitation because of water control; 3, mouth-to-mouth artificial respiration and heart * * *; 4. Contact the emergency center as soon as possible or send the drowning child to the hospital.

5. The knowledge about popular science is short, so write more.

Insects harmful to human beings 1. The harm of cockroaches, that is, people call oil thieves, sweet mothers, and slippery insects ... In many insect societies, its official name is cockroaches.

This is a global insect, widely distributed in five continents and four oceans, especially in tropical areas. They can be found everywhere in our country. ...

Cockroaches are flat, brown, dark brown, brown or brown, with metallic luster. There are two slender tentacles in front of their heads, which give off an unpleasant smell. Usually, cockroaches not only camp in homes, canteens, hotels, hospitals, warehouses and shops, but also haunt fields, forests, factories, farms and even ocean-going ships, warships and airports, endangering dozens of agricultural and forestry crops, cloth and groceries and causing economic losses to mankind.

Cockroaches feed on dozens of family foods. I especially like starch, sugar, vegetables and foods with high humidity.

In addition, it also likes to eat dozens of Chinese herbal medicines, such as Poria cocos, Chrysanthemum, Angelica, etc. Feces, phlegm and rotting animal carcasses are also its delicacies. When you are really helpless, you can eat the paste at the edge of the book and bite the pages; Even red and blue pencils's refill can satisfy hunger and sustain life.

In addition, they often bite clothes, get into radios and televisions, bite wire sheaths, and even bite babies' nails and eyelashes. They often excrete a lot of dirty feces in crawling foraging places, leaving a disgusting smell. Therefore, people's hatred was aroused.

Cockroaches are the disseminators of many human diseases. Cockroaches are known to carry more than a dozen epidemic bacteria such as typhoid Bacillus and dysentery Bacillus.

It is reported that the bacterial content in the tentacles, feet and stomach of each cockroach can be as high as 13370. In addition, cockroaches also carry human parasite eggs such as hookworms, roundworms and flagellates, which pollute food and spread diseases by touching, feeding and excreting feces.

In recent years, there are rumors at home and abroad that the excrement of Periplaneta americana has carcinogenic effect. However, it is worth mentioning that although cockroaches are the enemy of mankind as a whole.

However, there are also useful categories in its camp. We should protect and use it.

For example, a cockroach named "Eupolyphaga sinensis", the female of which is a famous Chinese medicine "Eupolyphaga sinensis", is salty, cold and toxic, and has the effects of breaking blood and driving away gangrene, and is mainly used to treat blood stasis; Amenorrhea and traumatic injury. For this kind of species, there are monographs at home and abroad, and there are specialized units or specialized households to raise them.

Cockroaches, as a sanitary pest, do great harm to human beings. Health organizations and epidemic prevention departments in many countries in the world have taken it as the elimination target, and invested a lot of manpower, material resources and financial resources in its classification, living habits, environmental ecology, prevention and utilization. Two. Types of cockroaches Most people think that all the cockroaches they see are one kind.

In fact, there are no fewer than 10000 species of cockroaches in the world. More than 6,000 of them have been studied by scientists and have scientific names.

There are more than 200 recorded species in China. Cockroaches are various and widely distributed.

But what is closely related to human livelihood is probably mainly cockroaches living indoors. As early as 1095, it was recorded in Li Shizhen: "Nowadays, there are so many cockroaches under people's walls that they even get together to dry up to 100 cockroaches. They are like silkworm moths, with red bellies, flying wings and smelly breath like lamps. "

If you look closely, you will find that there are cockroaches indoors, big and small, with wings and short wings. The large and wide chest backboard covering the head and chest is dark in color, some masks have two brown longitudinal bands, some have spots and patterns, and some are irregular ... All these signs show that they are not the same. Therefore, in its external form, it shows great differences and differences.

At present, research indicates that there are dozens of species of cockroaches that endanger indoor environment. Our country varies from place to place. The most common ones are Periplaneta americana, periplaneta fuliginosa, Periplaneta australis, Periplaneta japonica, Periplaneta punctata and Blattella germanica.

Three. Long history When we open the family tree of cockroaches, we will be surprised to find the family history of cockroaches. According to the examination of two cockroach fossils by American scientists with C 14, it is confirmed that they have a history of 300 million years.

What a long time! At that time, dinosaurs had not yet come out, and cockroaches were already subjects of the earth. They read all the vicissitudes of life and struggled tenaciously with nature to survive. What is even more incredible is that cockroaches 300 million years ago are so similar to cockroaches that exist today, and the variation is so weak that people can't help but sigh: how tenacious cockroaches are! No wonder it is called "the living fossil of insects".

Four. Biological habits It usually takes more than six months to four years for cockroaches to complete a life cycle from egg to nymph to adult. Although indoor cockroaches have wings, they can't fly very well, probably to avoid being chased when stealing food. They have all trained three pairs of "Scud" and are very good at running and crawling.

If a competition is held in the insect world, they will definitely monopolize the glans penis and win the gold medal. Probably ashamed of their furtive behavior, they are always afraid of the light, living in seclusion during the day, hiding in dark corners, such as the wall of sewers, around the stove in the kitchen, between wooden boxes, in clothes, in the pages of books and so on. And only at night do they eat out in droves.

Interestingly, their eggs are all laid in a cortical egg sheath, which looks like an old lentil. Look carefully, there are often rings on it. There are dozens to dozens of eggs in this elaborate account.

Usually, females can produce fourteen or fifteen egg sheaths in their lifetime. Some "mothers" are afraid that their children will be attacked by foreign enemies before they hatch. They always hang the egg sheath at the end of the abdomen for two or three weeks. Only when the eggs inside are about to hatch into nymphs, they put it in a carefully selected safe and comfortable place and let them come to this world alone and travel around the world.

Verb (abbreviation of verb) Prevention and control of indoor cockroaches. Indoor cockroaches breed quickly and have a large number, which is found in almost every household in the south. People can often hear their complaints about them and seek a panacea to destroy them. In the long-term struggle against cockroaches, human beings have accumulated some effective control measures, which can be summarized as follows: (1), the source of eliminating insects: preventing the spread of cockroaches, especially egg sheaths.

(2) Artificial killing: Cockroaches use their nocturnal habits to move at 9- 1 1 at night.

6.50 Less scientific knowledge

1. Rabbits beat the ground with their legs to transmit information, mostly with their hind legs, which is a way for them to express their feelings to female rabbits. 2. The biggest monkey in the world is a baboon and the smallest monkey is a bonobo. 3. The real name of "Four Elephants" is Elk, which is a rare animal in China. 4. Why does sorbet get angry? The reason why sorbet bubbles is because there is a lot of invisible water vapor in the outside air. When it comes to cold sorbet, it will liquefy into droplets when it is cold. It seems that the sorbet is bubbling.

5. Why do sunflowers always face the sun? Sunflower stems contain a wonderful auxin. This auxin is very afraid of light.

When it is illuminated, it will go to the backlight side, and the cells on the backlight side will multiply rapidly. Therefore, the backlit side will grow faster than the bright side, which will bend the sunflower to light. 6. Why do cicadas shed their skin? Cicada's shell (exoskeleton) is hard and can't expand with the growth of cicada. When the cicada grows to a certain stage, the cicada's exoskeleton restricts its growth, and the cicada loses its original exoskeleton, which is cicada slough.

7. How do bees make honey? First, the bees spit the sweet juice of the flowers they picked into an empty hive. At night, they suck sweet juice into their honey stomachs to make it, and then spit it out and swallow it. It takes 100~240 times to make sweet honey. 8. Why do the stars twinkle? We see the stars shining, not because the luminosity of the stars has changed, but because of the occlusion of the atmosphere.

The atmosphere is between us and the stars. When starlight passes through the atmosphere, it will be affected by the density and thickness of the atmosphere. The atmosphere is not absolutely transparent, and its transparency will change according to its density.

So when we look at the stars through it on the ground, we will see that the stars seem to be flashing. 9. Why do people yawn? When we feel tired, a lot of carbon dioxide has been produced in our bodies.

When there is too much carbon dioxide, oxygen must be supplemented to balance the needs of the body. Because these residual carbon dioxide will affect our body's functional activities, then the body will send out a protective reaction, so we yawn.

Yawning is a deep breathing action, which will let us breathe in more oxygen and expel more carbon dioxide than usual, and it can also eliminate fatigue. 10, why can a snake walk without feet? Snakes have many scales, which are the outermost armor on their bodies.

Scales are not only used to protect the body, but also to be their "feet". When a snake crawls forward, its body will be S-shaped.

Every scale outside the S-shape will tilt upward to help the snake catch the uneven road when it moves forward. These scales cooperate with the snake's muscles and can push the body forward, so the snake can walk without feet! 1 1. Why does hair turn white when people get old? There is a substance called melanin in our hair. The more melanin, the darker our hair will be.

Without melanin, hair will turn yellow or white. When human beings reach old age, various functions of the body will gradually decline, and the formation of pigments will be less and less, so the hair will gradually turn white! 12. Why do fireflies glow? Fireflies emit light because there is a luminous body at the end of their abdomen, which is filled with a lot of phosphorus-containing luminescent substances and luminescent enzymes, so that fireflies can emit flashing light.

The purpose of fireflies is not only lighting, but also courtship, vigilance and trapping. This is also a communication tool for them. Different kinds of fireflies emit light in different ways, frequencies and colors, so they can convey different information.

13. Why do you growl when you are hungry? When you are hungry, you will purr. This is because the food you have eaten before has almost been digested. Although the stomach is empty, the gastric juice in the stomach will continue to secrete. At this time, the contraction of the stomach will gradually expand, and the liquid and gas inside will be stirred up and purr.

Don't be embarrassed by your stomach growling next time! Because this is a normal physiological action. 14. Why can't ostriches fly? A giant ostrich, but they can't fly into the sky! This is not because their wings are useless, but because their feathers are too soft and their wings are too small to fly at all.

In addition, the ostrich's muscles are underdeveloped and its sternum is flat, which is not conducive to flying. Ostriches live in Africa. Because they have lived in desert areas for a long time, their bodies gradually evolved into what they are now in order to adapt to the environment.

15. Why can't the food in cans go bad easily? Lunch meat, black bean shad, tomato sauce beans.

They are all delicious canned food, which can be preserved for a long time without deterioration. This is because the can is sealed, so bacteria can't enter.

When people make canned food, they pump all the air out of the canned food and then seal it. In the absence of air, even if the food inside is contaminated with a little bacteria, they can't survive or reproduce! 16. Why does the baby cry all the time when it is born? Babies cry when they are born, not because they are unhappy, but because they are taking the first breath of air! When babies leave their mother's body and are born, the first breath of air will rush to their throats, violently impact the vocal cords, make them vibrate, and then make a sound similar to crying.

17. Why do lizards keep bouncing backwards when their tails are broken? In order to protect themselves, many lizards also protect their eyes and ears; When some lizards are attacked, their tails will be broken due to the severe contraction of their muscles. Because there are still some nerves alive in the broken tail, it will keep bouncing, thus distracting the enemy and running away.

Don't think that their lives will end like this. In fact, it only takes a few months, and their tails will grow back and move on. 18. Why is the squirrel's tail so big? Don't look at the relaxed mouse tail! When the squirrel jumps around the tree, its tail plays a great role.

It can keep balance when the squirrel jumps to the tree to avoid falling and being injured. In addition, this big tail can play a more protective role in winter, tightly surrounding the squirrel's body, which is convenient and practical.

19, why can't a human thumb have one or three knots? The average person has five fingers, each with a different length.

7. Who has popular science knowledge or short articles for me ~

Scientific paper

The relationship between human or animal survival and plants

Not long ago, many plants were added to grandma's house, and bonsai was placed at the door, living room and balcony. I said to my grandmother, "Our home has become a botanical garden. Why are there so many plants? " Grandma smiled and said, "Plants can make oxygen and purify the air. No one can live without them. " People or animals cannot live without plants? Why can't people or animals live without plants? I'll be skeptical. Decided to do a few small experiments to solve this problem.

On Sunday, I asked my brother to go to the garage to catch two mice. These two poor little mice will be my experiments. They kept struggling, their little round eyes staring at me. I put the first mouse in a big fish tank, and sealed the mouth of the fish tank with plastic wrap, lest the air in the bottle communicate with the outside air. I watched carefully and saw the little mouse scurrying along the cylinder wall and around the bottom. Hey, isn't the mouse alive and well? Isn't what grandma said true? However, in a few minutes, I saw the little mouse winding slower and slower until it was stagnant and dying. Suddenly, I gently removed the disposable plastic wrap, grabbed the first mouse, put the second mouse in, and moved into four pots of leafy plants. Then gently cover with disposable plastic wrap. I kept patting the fish tank, only to see the little mouse scurrying about in panic, and it took a long time to die. This experiment proves that plants can transport the oxygen that animals need.

In order to further prove the dependence of humans and animals on plants, I came to my mother's original factory. The air there is full of dust noise, which makes me cough. I feel very uncomfortable. Then, I ran to a bamboo forest in Guiyuan. It is a place with fresh air, and I feel extremely refreshing. This experiment proves that plants can purify the air and make people breathe smoothly.

These two experiments prove that the survival of human beings and animals is closely related to plants. How scientific is this? Our scientific and technological team went to the library to consult many scientific and technological books, and also went to the electronic reading room of the school for online inquiry, and summarized the following points: ① People must rely on plants to provide oxygen, and only plants can make oxygen. If a person doesn't eat or drink for a few days and still has a breath, he may die if he doesn't breathe for a few minutes. Oxygen is the first need of human life activities! An adult breathes about 20,000 times a day, inhaling 0.75 kg of oxygen and exhaling 0.9 kg of carbon dioxide. (2) Breathing of animals and plants and burning of substances also consume oxygen and release carbon dioxide. So, isn't there more oxygen in the air every day? Don't! The reason why there has never been such a crisis between heaven and earth is that plants are both "factories" of natural oxygen and "broad markets" of carbon dioxide. According to statistics, 1 hectare of broad-leaved forest can produce 750 kilograms of oxygen and eat 1 1,000 kilograms of carbon dioxide every day during the growing season. Therefore, as long as there are 6.5438+10,000 square meters of trees, it can supply 1000 people's oxygen demand and absorb exhaled carbon dioxide. Because there are plants that constantly supplement oxygen, the oxygen in the air can be kept basically constant. On the contrary, if there are no plants, the oxygen on the earth can be used up in about 500 years.

Plants are closely related to our human and animal lives. Here, we call on people in the whole society to stop cutting down plants and make them our best friends.

8. Less scientific and technological knowledge is shorter.

Our motherland is becoming more and more powerful, more and more developed and more advanced in science and technology! Looking at history, we have come step by step from ancient times to the present.

At that time.

At the ceremony, I have seen the scientific and technological development of our motherland, novel tanks, cars,

There are some rare weapons and equipment. I am surprised that the technology of our motherland is too developed now.

Technology is indispensable to us human beings, and we will use our technology anywhere.

Now our school is also holding this science and technology festival, so that students can write their own scientific papers or tabloids and invent them themselves.

Or draw a picture of science and technology, which not only improves students' love and understanding of science and technology, but also improves their practical ability. I also took part in this activity and found it very meaningful. I found some online.

And information, and parents with the brain, their own inventions.

How interesting and meaningful it is to draw your own imaginary scientific and technological paintings!