If you don’t learn these scientific knowledge, you may not understand "Nezha 2"!

According to online platform data, on February 18, the cumulative box office (including pre-sales) of "Nezha: The Devil Boy Conquers the Dragon King" ("Nezha 2") exceeded the box office performance of "Inside Out 2", topping the global animation film box office list and entering the top 8 of the global box office list. It is a wonderful movie that you can watch N times without getting enough. And do you understand some of the scientific codes hidden in the movie?

Nezha's scientific wisdom: Water conducts electricity, but ice does not

In the movie, Nezha has a super cool fight scene with a character who can transform into electricity and move instantly. Nezha cleverly uses a physical phenomenon - water conducts electricity while ice does not, restricting the opponent's actions and defusing the crisis. Why can water conduct electricity but ice cannot?

Transformed into lightning and fled at high speed. From the trailer of "Nezha 2"

Strictly speaking, pure water is not conductive. This is because there are no electrons or ions that can move freely in pure water. However, the water we usually come into contact with is often not pure. It contains many minerals, gases and other things dissolved in it. These dissolved things will become ions in the water, which are like small charged particles. These ions swim around in the water like a school of small fish, and they can transmit electric current.

However, when water turns into ice, the situation changes. The water molecules in the ice are arranged neatly, forming a very regular crystal structure. This structure is like building a wall for the ions, making it difficult for them to move freely. Therefore, in pure ice, there are almost no ions that can move freely, and its conductivity is very weak.

However, in real life, ice is not completely pure. It may contain a little bit of salt, minerals and other impurities. These impurities will also become ions, making the conductivity of ice slightly stronger, but compared with liquid water, the conductivity of ice is still far worse. This is because the crystal structure of ice has caused great obstacles to the movement of ions.

Ao Bing's tears flow upwards in the sea: because of the density difference

There is a scene in the movie where Ao Bing expresses his true feelings in the deep sea water, with tears in his eyes. But his tears flow upwards instead of flowing down his cheeks. Why is this so?

In fact, this is related to the density of the material. Seawater contains a lot of salt and other minerals, so its density is greater than that of ordinary fresh water. Moreover, the density of seawater also changes with depth and temperature. The density of deep seawater is usually greater than that of shallow seawater.

What about tears? Although they also contain some salt and protein, in general, their density is closer to the liquid inside the human body. Therefore, compared with deep sea water, the density of tears is smaller. Even in the sea water, due to the difference in density, there is still a tendency to "float upwards". Of course, "floating upwards" here does not mean that tears really float to the surface of the sea like a balloon, but that their movement trend in the sea water is upwards.

Coupled with the influence of various factors such as the flow of sea water, temperature differences, and salinity distribution, this may cause the wonderful sight of tears flowing upwards that we see.

Nezha's Super Mobility: The Science of Force and Motion

Nezha's various high-speed movements and fierce fighting actions in the film are full of power. From the perspective of physical force and motion, there is a lot of knowledge in this. Force is the cause of changing the state of motion of an object, which is what Newton's first law tells us. Nezha can shuttle quickly in the air and fight fiercely with the enemy because he constantly applies force to himself and the objects around him.

When Nezha uses the Hun Tian Ling to attack the enemy, it exerts force on the enemy and changes the enemy's state of motion. When Nezha himself moves and turns quickly, he also uses his own muscles to generate interaction force with the wind-fire wheels under his feet and the air or the ground, thereby achieving acceleration, deceleration and turning.

At the same time, inertia is also reflected in this process. Inertia is the property of an object to maintain its original state of motion. The greater the mass, the greater the inertia. Although Nezha is small in stature, his speed and strength change rapidly in battle, which seems to violate the principle of inertia. In fact, he overcomes his own inertia by constantly applying external force and achieves flexible and changeable combat movements. For example, he suddenly stopped during high-speed flight because he used the wind and fire wheels to exert force in the opposite direction of movement to overcome the forward inertia.

Nezha’s long pregnancy: a “slow-burning” life in reality

In the film "Nezha: The Devil Child Comes into the World", Nezha's mother, Madam Yin, was pregnant for three years and six months before giving birth to him. If this were put in reality, it would be more than three times longer than the normal human pregnancy period! In fact, similar situations really exist in nature.

For example, the gestation period of the basking shark is up to 4 years, which is the longest known gestation period of any animal. In addition, the gestation period of African elephants is about 22 months, that of Asian elephants is about 18-22 months, that of sperm whales is about 12-18 months, and that of walruses is about 600 days (nearly 2 years).

This is actually a survival strategy of "embryo diapause". Simply put, in order to allow the baby to be born in a more suitable environment, some animals will slow down the development of the embryo. It's like if the environment outside is too bad and the baby is not ready, it's better to stay in the mother's belly for a while and come out when conditions are better.

Nezha was born with a " shell ": cesarean section with preserved fetal membrane sac

When Nezha was born, he was a ball of flesh, which slowly grew fingers. Later, with the help of Taiyi Zhenren, he transformed into a complete human form. In real life, this method of delivery is often performed by doctors to preserve the amniotic sac in order to protect premature babies or very low birth weight babies.

Recently, in a hospital in Taizhou, Zhejiang, the real-life twins "Nezha" were born with "shells" like this. Ms. Chen (pseudonym) was pregnant with twins, and her pregnancy was full of challenges and hardships. At 16 weeks of pregnancy, she was hospitalized for fetal preservation due to cervical incompetence and underwent vaginal cervical cerclage. At 36+3 weeks of pregnancy, she was hospitalized again due to lower abdominal pain and was considered to be a sign of premature birth. However, premature babies have immature organs and incomplete nervous system development, and are much more fragile than full-term babies. After full consideration, the obstetrician decided to put on a layer of "protective clothing" for the babies - performing a surgical method to preserve the fetal membrane sac.

Cesarean section with retention of the membranes is to deliver the fetus and its appendages intact without rupturing the membranes. The advantages of cesarean section with retention of the membranes are obvious: the fetus is always in a familiar intrauterine environment during delivery, avoiding the impact of sudden changes in air pressure on immature organs, which is particularly suitable for the delivery of premature babies.

The fetal membrane usually ruptures before the fetus is delivered, which is called rupture of membranes. In a few cases, the membranes do not rupture, and the fetus is born wrapped in a translucent fetal membrane. For example, some premature babies are more fragile, and the amniotic membrane has not yet experienced natural aging in the third trimester, so it has a higher toughness, which makes it difficult for the amniotic membrane to rupture during delivery, thereby increasing the possibility of a "baby with a shell". In addition, when the fetal membrane is thick and has not ruptured due to uterine contractions or fetal head squeezing, or when delivery is completed when the labor process is fast and the amniotic membrane has not completely ruptured, it may also lead to the birth of a "baby with a shell".

The magic pill and the spirit pearl: the love-hate relationship between genes and the environment

The fate of Nezha and Ao Bing also gives us a vivid biology lesson. Nezha is the reincarnation of the "magic pill" and should be a bad boy, but he finally becomes a hero; Ao Bing is the reincarnation of the "spiritual pearl" and was born with a good fate, but he almost went astray. Behind this, there is actually a scientific principle of the interaction between genes and the environment.

Genes are like the "blueprint" in our bodies, which determine our basic characteristics and potential. But the environment is like the "construction team". The acquired growth environment and education methods will affect how this "blueprint" will be built. Just like Nezha, although his genes carry the setting of "magic pill", he has loving parents and masters, these good "construction teams" helped him get on the right path; and Ao Bing, although his genes are "spiritual pearls", was led astray by Shen Gongbao, the "bad construction team". This is a living example of "gene + environment" affecting individual development!

Modern biological research shows that epigenetics (the influence of the environment on gene expression) plays a key role in individual development. The story of Nezha and Ao Bing is a vivid reflection of this!

Nezha's "shark teeth" and "panda eyes": common phenomena in children's development

In the movie, Nezha's image is very unique, especially his jagged "shark teeth" and iconic "panda eyes", which left a deep impression on the audience. From a health perspective, these image designs have hidden mysteries.

Nezha's "shark teeth" are similar to those of children in real life, which are called the "ugly duckling period". Children usually start to change their teeth at around 6 years old, and it is normal for gaps between deciduous teeth to appear. As the lateral incisors erupt, the gaps between the central incisors usually disappear gradually. However, if the permanent lateral incisors have erupted after the age of seven or eight, but the gaps between the central incisors have not closed, you should take your child to the hospital in time to assess whether early childhood correction is needed. If a child's teeth are particularly sharp and always scratch the tongue or cheek mucosa, you should also go to the hospital for appropriate adjustment.

Look at Nezha's "panda eyes", which are mostly caused by staying up late, lack of sleep, stress, etc., the main reason is lack of sleep. For children, long-term use of electronic products and staying up late may also cause dark circles.

Nezha's Lotus Root Incarnation: Miraculous Regeneration of Plants

In the movie, Taiyi Zhenren uses lotus root powder to reshape Nezha's body, a plot full of fantasy. In the more popular folk legend, "reshaping Nezha" uses lotus roots as bones and lotus as flesh. From a biological point of view, this involves the regenerative ability of plants. Plant cells are omnipotent, which means that each cell of a plant contains all the genetic information to develop into a complete plant. Under suitable conditions, even if the tissues or organs of a plant are damaged, they can regrow the missing parts through cell division and differentiation.

Just like when you plant cuttings, you insert a branch into the soil, and it can take root, sprout, and grow into a new plant. This is because the branch cells restart the division and differentiation process under the water, nutrients and suitable environment provided by the soil, forming new roots and stems. This regeneration ability is widely used in agriculture and horticulture, such as cutting propagation of flowers and fruit tree grafting, which all use the omnipotence and regeneration ability of plant cells to achieve plant reproduction and variety improvement.

Source: Science Popularization China, Taizhou Evening News, Haimen Science and Technology Museum Small Classroom, Dongguan Qiaotou Hospital, Teacher Che's Biology Micro Classroom