The palace officials left with satisfaction.
It was the right decision to hand over his prince to Xu He.
Zhang Huan led Xu He to his study.
As soon as he sat down, Zhang Huan smiled bitterly and said: "Brother-in-law, don't tell me those big principles. I really want to know the distance between heaven and earth!"
Xu He thought for a while and asked a question: "Your Highness, what do you think our feet look like?"
"Of course it's flat!" Zhang Hao drew two lines on the paper.
He tapped the line above with his pen: "This is the sky!"
Then he clicked on the following line with his pen: "This is the ground!"
Come to him, take the pen from his hand, then draw a circle on the paper, and then draw a person at the bottom of the circle.
"This is where we stand. The place we live in is actually a sphere called the Earth!"
"Earth?" Zhang Huan shook his head: "Your statement is too strange and impossible. I am clearly stepping on flat ground."
"The earth is so big that when you look at it with the naked eye, it's flat as far as you can see!"
"Has Your Highness ever seen the sea?"
"No!"
"If you have a chance, your highness, go and take a look at the sea. A ship will come towards you on the sea. The first thing you see is definitely the sail, not the whole ship!"
"Why is this happening? If, according to His Highness, we are on the same plane, then we should be able to see the entire ship, right?"
One question left Zhang Huan completely speechless.
He still needs to find an opportunity to verify this matter.
But: "But, brother-in-law, the little man you drew is head down. Doesn't he fall into the sky?"
"Come on, let me tell you what the rotation and revolution of the earth are, and then I'll tell you what atmospheric pressure and gravity are!"
…
For more than an hour, Xu Hecai taught Zhang Quan some basic knowledge of current astronomy.
"It's incredible!" Zhang Huan shook his head and said, "Brother-in-law, what you said is too..."
This is the first time I heard that if I stand on a round ball, it will not fall down even if it is turned upside down. This is indeed hard to understand and very shocking.
But, doesn’t anyone know the nature of this world?
no.
"Your Highness, do you know Zhao Youqin?"
"Who is he?" Zhang Hao asked confused.
Xu He smiled and said: "The eleventh generation grandson of Song Taizong, who lived in the Yuan Dynasty BC. He wrote a book called "The New Book of Gexiang"!"
Zhang Huan may really be an astronomy enthusiast, and he listened with great concentration.
"According to Zhao Youqin's "New Book of Gexiang": Although the earth is round, it can't be seen for hundreds of miles or dozens of miles, and the human eye can't focus on it. I tried boating in the rivers and lakes, but I saw bulges wherever the boat went. When water comes, you cannot see its head; when water goes, you cannot see its tail. The Dongting is so vast that if the sun and moon appear and disappear in it, the distant mountains are all under the ring and are not an obstacle. Measure the height of the North Pole above the ground, and the moon in the east and west directions. Morning and evening at the time of eating, the earth's body is round, and the earth's order corresponds to the heaven's order!"
What does that mean? Probably translated as...
The earth we live on is round, so why can’t we see that the earth is round even if we look a hundred or dozens of miles away?
The answer is: because our human sight is straight, not curved.
Therefore, the ground we see can only be flat. Just like when we row a boat on a lake, the water surface will rise wherever the boat reaches, but we cannot see the movement of the water.
For another example, it seems to us that the sun and moon rise and set on the surface of Dongting Lake, but in fact the sun and moon do not fall into Dongting Lake, and the mountains in the distance do not block the sun and moon. Why?
Because the earth is round, the flat ground we see is just an illusion. I have observed the visual differences between the north and south poles on the ground, and also observed the changes in the east and west of the lunar eclipse, which have been irrefutably proved:
The Earth is round!
However, what is interesting is that Zhao Youqin was not the only ancient Chinese who knew that the earth was round. There are people. who? Zhang Heng.
Yes, it is the Zhang Heng who invented the legendary moving instrument (note: it is a legend). Zhang Heng also believed that the earth is round. He wrote in his "Notes on the Armillary Sphere"
"The sky is like a chicken's egg, and the earth is like the yolk of an egg. I live alone inside. The sky is big and the earth is small."
Translated into adult language, this is what it means
"The universe is an egg, and our earth is like the yolk, alone inside the egg. The universe is huge, but the earth is small."
Look, Zhang Heng also made it very clear, and what he said is generally consistent with the facts.
It can be seen that Zhang Heng is also very smart.
In fact, our Chinese ancestors are really many smart people! There is another person, Zeng Zi, a figure in the Spring and Autumn Period. Although Zeng Zi did not explicitly state that "the earth is round", Zeng Zi raised strong doubts about the statement that "the sky is round and the earth is round". He wrote in "Zeng Zi·The Sky is Round" said:
"Just as the sky is round and the earth is round, the four corners are not covered!"
Translated into human language, it means this:
"If the sky is a round cover, and the big one is a square piece of cake, then I would like to ask, how does this round cover cover the square earth? The four corners of the earth, it It can’t be covered!”
"Look, our sage Zengzi was also a very smart man."
Zhang was confused.
Zengzi knew it. He had also read this sentence, "If the sky is round and the earth is square, the four corners cannot be concealed." But he had never thought about it.
But the man in front of him who was about to become his brother-in-law not only raised the alarm, but also found numerous ancient books to prove the existence of that [Earth].
This is very... admirable!
Zhang Yue sighed sincerely: "I have seen a lot of top picks, but this is the first time I have seen a top pick like my brother-in-law!"
Xu He smiled and said: "It is rare to see a prince who is interested in astronomy like His Highness!"
The two looked at each other and smiled, and Xu He said at this time: "Now that Your Highness knows the atmosphere, I can tell you what the distance between heaven and earth is!"
"The sky is actually two concepts. One is sky and the other is emptiness. Looking up from the ground we are standing on, the place 200 miles away from the ground is the boundary of the sky. If it is more than 200 miles away, it is emptiness. I call it space!"
"Why two hundred miles?"
Don't ask, it's another time and space, as defined by the International Aviation Federation!
"This question is something that even you, Your Highness, cannot understand!"
"Ah, that's it!" Zhang Yu said with a look of shame on his face, "My brother-in-law's knowledge makes me feel like I'm standing on a high mountain! I'm really ashamed!"
Xu He smiled: "Your Highness is interested. We can also talk about what physics and chemistry are in the future! Inglesi can also discuss it!"
Zhang?'s eyes lit up and he said excitedly: "Brother-in-law knows so many things, I want to learn them all!"
Haha, young people don’t know the heights of the world, want to learn? Since you are so eager to learn, let me let you experience the power of Doomsday Junior High School.
I hope that in the future you can still maintain your original intention and want to learn instead of crying!
