The right and wrong between the round earth theory and the flat earth theory has always been a very controversial topic.
When I introduced Zhang Zai before, I mentioned the origin of the round earth theory.
Later generations generally believe that the round earth theory officially appeared in the century BC.
It was the ancient Greek mathematician Pythagoras who first proposed the concept of the earth.
Wait until the century B.C.
Eratosthenes, a scientist who lived in Alexandria, used geometric methods to establish the concept of the earth and calculated its diameter.
But what was not explained at the time was that Eratosthenes' method was actually very stupid.
He unexpectedly learned that at noon on the summer solstice every year, the sun's rays would shine directly on the bottom of a deep well in Sain, Aswan, Egypt.
at the same time..
In the city of Alexandria, which is just north of Saine in Greece, the angle between the sun's rays and the vertical line on the ground is π radians, which is degrees.
Assume that the sun's rays are parallel.
Then according to the formula for calculating the circumference of a circle, we can get a value
That is, the circumference of the earth along the meridian passing through the north and south poles = xπ÷π&bsp&bsp=&bsp&bspGreek miles.
This is just a theoretical derivation, and it can only be said to unify some people's perceptions.
In fact, the theory of a round earth does not just say that the earth is flat with one punch as the data or formulas are solved.
Throughout human history.
There are people in almost every dynasty and every generation who do not believe in the theory of a round earth.
Even in later centuries, supporters of the flat earth theory were not uncommon.
For example, now, there is a Flat Earth Conference held across the sea every year - for the most recent conference, many people even came to attend.
The number of online participants has reached 10,000 real people, and the domestic live broadcast platform has reached a million-level popularity every minute.
YouTube is also filled with various videos claiming to prove that the earth is flat.
Nowadays, local civil science is regarded as a derogatory term. For example, you can see various design guides like Bagua arrays on the design drawings, or ghost symbols comparable to Xu Yun's calligraphy.
But in front of supporters of the flat earth theory, these civil sciences are really not enough.
Supporters of the flat earth theory believe that the round earth theory is a complete hoax.
The photos of the outer space of the earth are false images taken by the rulers to confuse us, and they are false truths to trap and enslave human beings.
Among them, NBA star Owen is a well-known supporter of the flat earth theory.
Precisely.
He is a 'follower' of one of the "Pac-Man cults"
This sect believes that the earth is flat. If you reach the boundary of the earth, you will instantly appear from the other side of the earth, so you cannot discover that the earth is flat...
The Kangaroo Country is the opposite country. At one time, there was a kangaroo singer with an atrophied cerebellum who was regarded as a defective product that stopped time.
By the way.
Another star Curry believes that the moon landing was fake and a complete scam.
without any exaggeration.
In the Flat Earth sect, there are countless such bizarre and bizarre statements.
They have the reputation of not trusting authority (which is actually true), but what they do is all kinds of anti-intellectual and even terrifying things.
Actually.
The flat earth theory is a key fulcrum of the Communist Party's layout, and it is also the core basis of conspiracy theories.
The specific content is too sensitive,&bsp&bspI won’t go into details here.
all in all.
The world is far crazier than we imagine.
This is still the case in later generations, let alone ancient times when the theory of a round earth was not an axiom.
Let’s just talk about the three people in the room at this time.
As a professional astronomer who has drawn star maps, Lao Su's acceptance of the theory of a round earth is higher than others.
He even has some tendency to believe that the earth is round.
But Xiao Li and Xiao Zhao are different.
Although these two young men are very interested in science.
But they have never received any systematic and correct scientific education.
Therefore, when Xu Yun mentioned earlier that the earth was round, some doubts naturally arose in their minds.
If it weren't for the fact that Lao Su listened with great interest.
Xiao Li might have interrupted Xu Yun long ago and asked angrily.
in the house.
Looking at the excited Old Su and the confused Xiao Li, Xu Yun pondered for a moment and said
"Sir, have you ever been to the beach? I mean the endless sea."
Lao Su nodded when he heard this and recalled
"Nine years ago, I was ordered to go to Dengzhou to check the navy's food and salary issues, so I have seen the ocean.
The water in my mouth was flowing from the sky to the sky, and I was so shocked that I almost lost my countenance on the spot.”
Dengzhou.
It was Penglai City in Ludong Province in later generations.
There is the famous Dengzhou Port here, which was also the core place for the Song Dynasty's naval garrison.
Penglai is close to the Bohai Sea and the Yellow Sea, and it can indeed be said to be endless.
Then Xu Yun turned his head again and looked at Xiao Li and Xiao Zhao.
I saw Xiao Li thinking for a moment,&bsp&bspShaked his head
"My father was an official in Huangzhou earlier, and he only crossed the river and never saw the sea."
Xiao Zhao on the side glanced at Xiao Li and said slowly
"I am different from Miss Li.&bsp&bspI went to Changguo County two years ago to purchase medicinal materials for Brother Wang.
The state of Chang is adjacent to the East China Sea, so we are fortunate to have seen the majesty of the sea."
The Chang State of the Song Dynasty is now Zhoushan, Zhejiang Province.
It is connected to the East China Sea and is also the estuary of a vast world.
Three people, two have seen the sea.
Although this ratio is far from perfect, it is much higher than Xu Yun expected.
Then Xu Yun pondered for a moment, and asked Lao Su and Xiao Zhao
"Sir, Your Highness Prince Jian, while you are admiring the sea view, have you ever seen a sailboat sailing from a distance?"
Later generations have been quite controversial about the time when sailing ships appeared in ancient China. They are mainly divided into two views: the Spring and Autumn Period and the Han Dynasty.
This chapter is not finished yet, please click on the next page to continue reading the exciting content! However, no matter which of the above situations is the case, the timeline must be far earlier than the current Song Dynasty.
So sailing boats are now very common, especially on the beach.
Therefore, Xiao Li and Lao Su just looked at each other and nodded in unison.
"I've seen it before."
Xu Yun nodded slightly towards the two of them, took a deep breath, and threw out his trump card.
"In this case, when you saw the sailboat, did you notice one thing?"
"What's up?"
"Which part of the sailboat first appeared in your field of vision?"
Hearing Xu Yun's words,&bsp&bspLao Su and Xiao Zhao were both stunned.
"Which part?"
Xiao Zhao saw Dahai only two years ago, so his impression was naturally relatively deep, so he took the first step and said:
"If I remember correctly, when the Japanese king climbed up to look at the sea, the first thing he saw seemed to be the white sails, and the second was the hull."
After hearing what Xiao Zhao said, Lao Su also recalled some scenes.
I couldn't help but nodded slightly in agreement.
But as he thought about it, he suddenly realized something.
His eyes widened sharply and he looked at Xu Yun, his mouth trembling slightly.
"Xiao Wang, are you saying that we saw the sail first because the earth is round, so the sea blocked the hull behind?"
Xu Yun was silent for a moment and nodded solemnly and firmly.
"That's right."
When a ship is sailing on the sea, you see the sail first and then the hull.
This is the strong evidence that Aristotle once mentioned when proving the shape of the earth.
Of course.
In real life, if you want to verify this statement with the naked eye, it is actually quite troublesome.
Because according to r?? d??=(r h)?? it can be calculated that a person with a sight height of meters can see a horizon distance of kilometers.
If you stand on a hill or on a high-rise building, you can see even further.
With such a vision range starting at more than ten kilometers, it is actually difficult for ordinary people to distinguish the sails, masts and hull of the ship.
In this case, the reason why the sail is seen first is largely due to the conspicuousness of the sail and has nothing to do with sea level.
But it is worth mentioning that Dengzhou and Changguo are two very special places, different from ordinary coasts.
They were all important places for the navy of the Song Dynasty, and they were also the location of famous sea markets in the Song Dynasty.
Now is the period when the Song Dynasty's sea market was at its most developed, and trade was connected not only with the mainland, but with the surrounding countries.
All ships involved in transoceanic trade are often of unusual size.
For example, the famous ancient ship from the Song Dynasty, the Huaguang Jiao was discovered and restored.
The entire ship's hull is about 30 meters long, about 30 meters wide, and about 10 meters deep. This was only the size of a medium-sized ship in the Song Dynasty.
For example, Dengzhou and Changguo were two maritime cities and important military areas.
If you are lucky, you may even see a sail boat with a 2,000-material level.
As for the so-called two thousand materials, they are almost in meters, width and depth.
That is to say, the displacement is 1,000 tons, which is about the same as the largest treasure ship in Zheng He's fleet.
For a large ship of this size, as long as the weather is good, it is not difficult to distinguish the sails and hull from a very distance.
One of Lao Su and Xiao Zhao was a former prime minister, and the other was the younger brother of Song Zhezong. They belonged to the top group of people in the Song Dynasty.
When they went to the sea market, it was as easy as drinking water to see this kind of ship.
Of course.
In the eyes of later generations, seeing the sails first does not necessarily mean that the earth is round.
Because from a possibility perspective, there is actually a possibility of a donut model.
But at this time, Lao Su obviously didn't think that much, and his mind was almost completely focused on what Xu Yun said.
As the top astronomer in China or the world at the moment - there is no one like him.
Lao Su's obsession with the stars has almost reached a point of madness.
Mentioned before.
Lao Su once made a telescope that could only magnify five or six times. The observation effect of this telescope was only slightly better than that of the naked eye.
In the year AD, Lao Su even took this useless telescope to Tubo in order to observe a star in the west direction!
That's right.
Tibet!
To know.
The Tubo of the Song Dynasty was not like later generations. At this time, Uizang and the Central Plains could be regarded as two different regimes, and there were even some small-scale conflicts between them.
Not only is the journey from Bianjing to Tubo long, but the risks are also staggeringly high.
But in order to pursue the truth, Lao Su did it without hesitation - and the result was the star on Su Song's star chart.
This is Lao Su, a great man of the times who is so persistent that he is not afraid of life and death.
Otherwise, with the same technological level, Lao Su could draw a star map with hundreds of more stars than Europeans. Do you really think it was all about luck?
And as a seeker who has spent a lot of effort on the star chart.
While Lao Su was looking up at the stars, he naturally thought about another thing.
What do the stars in the sky and the earth beneath my feet look like?
Unfortunately.
Lao Su's telescope was said to be for long-distance viewing, but in fact it had almost no substantive effect in front of the starry sky.
The real telescope in human history would not be invented until 2010 by Hans Lieber, and Galileo transformed it into an astronomical telescope. Only then did humans truly see the stars above their heads.
before that.
Even for a genius like Lao Su, the only round planets that could be seen with the naked eye were the moon and the sun.
After all, what is special about him is his brain, not the mutation of his body.
But now with the appearance of the sailboat example cited by Xu Yun, Lao Su suddenly realized
It turns out that the truth was once so close to me!
at the same time.
Perhaps he was inspired by Xu Yun's words.
Another memory fragment came to mind in Lao Su's mind
More than ten years ago, he once visited Fengcheng in ancient Fengzhou, which was also the capital of later generations of Guangdong people's favorite food.
One night during this period, he was enjoying the cool air in the courtyard and raised his head to look up at the stars as usual.
It didn't take long for him to follow his accumulated habits and experience and discover the eternal purple star in the north.
But just watch and watch.
A strange feeling suddenly arose in Lao Su's heart
The Ziweixing he saw in Fengcheng seemed to be a little lower in altitude than the one he saw in Bianjing.
However, Lao Su didn't think much about it at that time. He just thought that he was a little tired from the long journey and there were some deviations in his judgment.
After all, the reduced distance difference is not very obvious, it is very weak, almost nonexistent.
If it weren't for the fact that he often looked up at the stars, he probably wouldn't even have that weird feeling.
But now if according to what Xu Yun explained, the entire land is a circle
Then this height problem can be explained.
Because the earth is round, Ziwei Star is in the extreme north.
Therefore, the further north you go, the higher the purple star will be, and the further south you go, the lower the purple star will be.
The lower!
That's right.
See here,
Many students must have guessed Ziweixing's identity.
It is what later generations call the North Star, Gou Chen Yi!
But what Lao Su didn't know was.
In his eyes, the so-called eternal North Star is not actually a fixed star, but just a fixed title.
Just like the emperor's throne, different people can sit on it. You will sit on it today, and he will sit on it tomorrow. The trees in Chongzhen will laugh hahaha.
At present, the polar star Gou Chenyi, which we call very romantic in China, is known internationally as Alpha Ursa Minor.
In fact, it is still about an arc-minute away from the North Celestial Pole, about as far as a moon.
As we all know.
Due to the precession of equinox, the direction of the Earth's rotation axis on the celestial sphere is constantly changing.
So every once in a while, a planet will come to that location.
For example, friends who have lived from BC to now should all know,
The North Star at that time was not Gouchenyi, but Vega.
The North Star in BC was A Draconis, which is the right axis.
It is a dim fourth-magnitude star that is very inconspicuous in the sky - for comparison, Gouchenyi is a magnitude star, and Vega is a magnitude star.
By the year AD, Polaris will become Gamma Cephei.
From a theoretical perspective, there may only be three long-distance runners on the planet today who have a chance of surviving until then.
By the way.
Antarctica also changes on the celestial sphere.
For example, right now, there are no bright stars near our South Pole.
But by the year AD, there will be a bright Antarctic star - I Carinae, which is also a star of magnitude 2.
By the year AD, the South Pole star will be the brighter Delta Vela, which is also the third star in the sky.
But at this time, Lao Su didn't know this secret. He only had another question in his mind.
"Xiao Wang, although the example you gave seems to be able to explain the theory of a round earth, it is still not as good as seeing it with your own eyes."
I saw him staring at Xu Yun, his fists clenched tightly.
"So do you have a way to let me and others see what the stars look like with their own eyes?"
Xu Yun glanced at him and nodded.
"have."
Plop——
Lao Su's heart suddenly twitched heavily, his eyes widened, and he subconsciously blurted out
"any solution?"
"telescope."
"Astronomical telescope? How to prepare it?"
Hearing what Lao Su said, Xu Yun innocently spread his hands towards him.
"The villain doesn't know."
"you do not know?"
Lao Su's voice suddenly rose a little higher, and his expression was full of doubts.
"How could you not know?"
When Xu Yun heard this, he glanced at Lao Su with a very puzzled look and spread his hands innocently.
"Master, you don't think that a villain knows everything, do you?"
Lao Su was stunned for a moment.
Seeing that his words seemed to have some effect, Xu Yun continued:
"Sir, I have only seen this kind of tool in the Fengling Yueying Sect's books, but I can barely remember the principle.
But if we want to prepare an astronomical telescope that can see the stars clearly, as well as the microscope mentioned before, there is a problem that must be solved first."
"what is the problem?"
Xu Yun's eyes flashed with an inexplicable light and he said