Earth was a new word for the Wen Dynasty people, who called the land they lived in the earth, and believed that the earth was square and the sky was round.

Therefore, when Tang Wenyuan proposed the word earth, some people raised questions.

"Your Majesty, what is Earth?"

"I'll talk about the earth later, but before that, I'll ask you a question, does anyone know where my Wen Dynasty is outside the frontier?"

"Back to Your Majesty, there is the Tianchi Kingdom in the north, the Wa Kingdom in the east, the Nanban in the south, and the endless mountains in the west."

"And what about the west of the mountains? What about the south of the Southern Barbarians, the north of the Tianchi Kingdom, and the east of the Dongwai? ”

"The sea, there is an endless sea on both sides of the southeast, as for the north of Tianchi Country, Wei Chen has heard that where is the extreme north, there are perennial glaciers, and human beings cannot survive."

Tang Wenyuan nodded in affirmation, "That's right, what about the farther away from the sea?" Further north in the Far North? ”

"This ......"

"Back to Your Majesty, it should be the end of the earth."

"Ladies and gentlemen, I will tell you what the earth is." Tang Wenyuan exchanged pencils and paper from the system mall, drew a three-dimensional ball, and then hung it on the notice board that had been made before.

"Ladies and gentlemen, what is this?"

"Balls."

"Your Majesty painted this?"

On the one hand, it is the development of the level of painting, on the other hand, ancient painting focuses on freehand rather than realism, which is why three-dimensional painting was first popular in the West.

"It's just a simple sketch, if any of you are interested in drawing, I can teach you that."

"I'm me, I'm going to learn." Song Wushuang hurriedly shouted.

Tang Wenyuan waved his hand, "I'll teach the painting later, let's continue to talk about the earth." ”

As he spoke, he drew an area on top of the three-dimensional sphere, "This is our Wen Dynasty." ”

"Your Majesty means ...... Is the earth round? ”

"How is this possible!"

"Yes, if it were round, wouldn't I be able to walk back to where I was if I stood where I was and kept going north?"

After careful consideration, some ministers shook their heads slightly, "Not really, if this circle is large enough, the person standing on top of the circle really can't feel that it is a round ball." Like an ant standing on top of a ball as big as the Forbidden City, it only feels like it's walking on the ground. ”

"But, where can there be such a big ball?"

Tang Wenyuan didn't explain, and continued to draw a small round ball next to the ball.

"This is the sun, it glows, it heats, and the earth spins on its own. Think about it, if Wen Chao is here, and the ball turns around, will the sun's light only shine on one side? ”

"Wechen understands, that's why there is a difference between day and night."

"It's unbelievable, it's incredible."

"According to what Your Majesty said, this earth must be very large, so on such a big earth, are there other countries in the sea?"

"This question is very good, but I don't know, maybe this earth is only the continent where our Wen Dynasty is located, and the rest is all oceans, or maybe there are other continents. It's all up for us to discover and explore.

However, according to my guess, there should be other lands and countries, but their seafaring skills are similar to ours. If those countries had great seafaring skills, they might have discovered us long ago.

But it is not excluded that there are other aspects, such as that they may have more powerful weapons and more advanced technology......"

Tang Wenyuan couldn't answer this question, he didn't even know how much the size difference between this earth and the earth he was originally on was there. There is no way to judge the latitude and longitude of the Wen Dynasty.

As for the scientific and technological development of other countries, as Tang Wenyuan said, there is also no way to extrapolate. You don't know what other countries have researched until you see it.

Just like the earliest China, gunpowder appeared very early, but it was actually used in weapons hundreds of years later.

The Wen Dynasty naturally also had gunpowder, but the application of gunpowder also stayed in the stage of fireworks for the time being.

"That'...... What about the moon? Lu Jinghong suddenly asked a question.

Tang Wenyuan drew a small circle next to the earth, "This is the moon, and the sun is far, far away from the earth, far away to ...... Well, if an adult walks normally, without eating, drinking, or resting, he will have to walk continuously for almost four thousand years before he can reach the sun.

And to the moon, eight or nine years is enough. In fact, there is also a moon in the sky during the day, but the sunlight is too strong to block the moon's light. And the light of the moon is also reflected by the sun.

Reflected light is easy to understand, do you use copper mirrors to reflect light? It's the same thing. ”

"Your Majesty said this, but Wechen has seen that on some mornings, the sun and the moon exist in the sky at the same time."

"Lord Wang has observed very carefully, but this is a normal phenomenon, and the sun and moon will shine together in the early morning and evening of the first and last quarters. It is worth mentioning that the earth does not only revolve on its own, it also revolves around the sun, and the moon revolves around the earth.

As for the other stars in the night sky...... In fact, they are all spheres of this kind, but they are too far away from us, and we can only see a small glowing dot.

And the earth revolves around the sun, this circle is elliptical, when it turns closer to the sun, the temperature of the earth will be high, then it is summer, and when it turns to the farthest place, the temperature of the earth is low, then it is winter.

The northernmost and southernmost parts of the country are not exposed to the sun for many years, which is why the glaciers are formed all year round......"

Tang Wenyuan said, and then drew a simple schematic diagram of the solar system, and the other planets can be drawn casually, just let everyone understand the position of the earth, the moon and the sun.

If today's class is taught by ordinary people, this person will definitely be regarded as a fool, and even beaten up.

But the person who gave the lecture was Tang Wenyuan, they didn't dare, and they couldn't doubt it.

"But...... Your Majesty, if what Your Majesty says is true, then where did the earth come from, and why did they revolve around the sun? ”

"This ...... Maybe there really are gods in control. ”

The question of the origin of the universe is very complex, and the cosmic explosion is only a theoretical assumption, and there is no evidence to show that the universe was created by the singularity.

Moreover, there is also gravity involved, black holes...... And so on and so on more complex astronomy, Tang Wenyuan couldn't explain it.

It is enough for everyone to briefly understand that the earth is round.

"Little dog, go and get the glass in my room, boil the kettle of hot water, get some ice, and by the way get a silver bowl. Next, I will do a little experiment for you to understand why it rains in the sky. Master Li, I want you one thing first. When water is boiled, why does the heat rise up? Instead of going down? ”

"This ...... Wechen didn't know. ”

"Actually, it's not just water vapor, as long as it's hot, it will go up. Let me first talk about the principle of rain, the water of the earth or the river, after being exposed to the sun, turns into water vapor and floats to the sky. These water vapors gather together in the sky to form clouds. When the clouds have gathered enough water vapor, the rain will naturally fall.

In summer, when the temperature is high and the sunlight is strong, the water on the ground evaporates quickly, and the clouds condense water vapor quickly, so heavy rains often occur in summer. In spring and autumn, water vapor evaporates slowly, so it is often light rain............"

Tang Wenyuan explained the process of rain to everyone, but they could not understand it at once.

There are a lot of things that you have to see to be able to understand.

After a while, the little dog took the things Tang Wenyuan wanted.

Tang Wenyuan originally wanted to use hot water to do the experiment, but considering everyone's ability to understand, he ordered the little dog to get the candle.

First poured water into the glass, and then threw a pebble into it, "Now let's assume that this pebble is Chang'an City." ”

Tang Wenyuan asked people to hold the glass in the air with a wooden strip and cover the mouth of the glass with a silver bowl.

Light a candle at the bottom of the glass.

As the temperature rises, the whole glass becomes blurry in a short time.

"Ladies and gentlemen, take a closer look."

Everyone nodded, only to see Tang Wenyuan take some ice cubes and put them in the silver bowl.

Gradually, small droplets of water began to appear on the wall of the cup, and after a while, these droplets flowed down the wall of the cup. After a while, a few drops of water occasionally drip down.

"Now you understand why it's raining, right? In winter, when the sky is cold, the water vapor will turn directly into snow. If the temperature drops suddenly, the water vapor will turn directly into hail, what else do you not understand? ”

"Unbelievable, really unbelievable......"

"Your Majesty, if this is how the rain is formed, is the cause of the great drought due to the lack of water in the area? Or is it too cold for years to evaporate surface water? ”

"This ...... It has little to do with the low temperature. Drought is caused by a variety of factors, such as climatic factors such as long years of lack of rain, human factors, and local man-made waste of water resources. Another important factor is that a lack of trees can also cause drought. ”

"Then Weichen can understand that if a large amount of ice is put on the clouds, the rain can be artificially controlled?"

"Being young is a four-dimensional activity, and Master Sun's idea is very good. This practice you propose is called artificial rainfall, and it is theoretically possible. It is very difficult to implement, and I hope that we can have this kind of technology in the Wen Dynasty in the future.

Lord Sun, I am going to set up a scientific research department, I wonder if Lord Sun is interested in becoming a supervisor? ”

"Weichen can't ask for it, thank you Lord Longen."

This person's name is Sun Yan, and he is a proud disciple of a scholar, and he is only twenty-four years old this year.

And Tang Wenyuan now needs this kind of person who can draw inferences from one case and have divergent thinking.

Did the ancients lack wisdom and wisdom? No, what they lack is innovative thinking and advanced knowledge for them to think about.

The greatest advantage of feudal society is that when the emperor puts forward an idea, they can mobilize the strength of the whole people to realize this idea.

This is a 3000 word chapter ha!