{Thank you for the 1000 reward of my friend Da Sui descendants and the reward of my friend Yijian 68} Under the gaze of the four eyes, as well as Liu Lanzi's curious eyes, Yang Yan groaned: "Astronomy is broad and profound, and it is impossible to talk about it, only half-understood.
Gaitian theory advocates that the celestial sphere is a semicircle covering the ground, which was first seen in the Zhou Ji Sutra, which is the most intuitive perception of the universe by human beings, and its contribution is to determine the four images of the southeast, northwest, and northwest.
After saying that, Hun Tian was good at Zhang Heng in the Han Dynasty, thinking that Hun Tian was like a chicken, and the earth was like a chicken in the yellow, and advocated that the celestial sphere was a circle to wrap the ground, which was a further exploration of the universe.
Some people in later generations think that the Hun Tian Theory is equivalent to the ancient Greek Earth Circle Theory, which is actually a kind of misinterpretation, the essence of the Hun Tian Theory is still the heaven and the earth is flat, whether it is the Gai Tian Theory or the Hun Tian Theory, its ideological foundation is inseparable from the five elements of Yin and Yang, projected into political life, it is still the Yang Gui Yin Cheap, Gangchang Ethics that set, and this is exactly the ideological system that Yang Yan wants to fight.
Yu Xi nodded: "Yang Fujun said well, Yu advocated armillary heaven said, an armillary sphere can solve its secrets, Zhang Heng in the Han Dynasty once made an armillary sphere, but unfortunately it was destroyed in the rebellion of Dong Zhuo at the end of the Han Dynasty, and then the method was lost, but Yu after years of research, finally reluctantly restored one, and now placed in Yuyao Township." “ "Oh" Cui Wan was surprised: "Yu Jun actually restored the armillary sphere" The history books contain, the armillary sphere has two, one of them is larger, the whole body is made of brass, divided into two weights inside and outside, the outer weight is composed of three intersecting large rings to form the skeleton of the armillary sphere, set up four pillars to support, the inner weight is fixed on the rotatable double ring of the skeleton with a shaft, the diameter of the double ring is eight feet, a lookout that can be pitched is sandwiched between it, the length is also eight feet, his biggest role is to mark the north pole of the sky and the south pole of the sky, and measure the equatorial coordinates of the celestial body.
The other is called the muddy image, the size is smaller, the diameter is two feet two inches, it is also cast in copper, it wraps the ground plane with a large round ball, the ground plane divides the round ball into two, half covered the ground, half is not underground, the ball is decorated with stars, the zodiac cloth is the sun and the moon and the five stars, and the foreign officials in the other 28 Suzhou are Chinese, and the white, black and yellow three colors are the three stars, that is, the three star meridians of Gan, Shi and Wuxian, which are pushed by water power, and the stars in the dusk correspond to the sky.
In short, according to the actual observation of the position of the sun and moon relative to the star, the sun and moon can be accurately placed in different parts of the ecliptic, and then by continuing to observe, you can understand the movement of the planet relative to the stellar background, so as to calculate the conjunction period of the traveling stars.
Yu Xi was quite complacent, and said with a slight smile: "He has a good day, when he asks Duke Cui to come to the mansion to have a look, I don't know what kind of doctrine Zhang is the monarch of the Yang Mansion."
He just asked casually, completely out of the psychology of showing off, after all, no matter how pure he is, he always has his own pursuits, and he is also very happy to show off his theoretical knowledge to others in order to obtain psychological satisfaction.
Yang Yan said unhurriedly: "I will think that the Xuanye Theory is more in line with the reality of the universe than the Hun Gai Er Theory. ” "Ugh" Everyone looked at Yang Yan together.
Xuanye is one of the three major schools of astronomy in ancient China, but because the theory was too advanced, it was not taken seriously by the rulers and was not widely disseminated.
This doctrine asserts that the universe is infinitely vast, that the sky has no color, and that it is only seen as pale because of its infinite height, and that the sun, moon and stars float in the void, relying on the action of qi, or moving, or stationary, and that the celestial bodies are in different states of motion and at different speeds, and are not attached to the tangible heavens, but float in the air.
Even from the perspective of modern people, the Xuanye theory is also quite significant, and its further development believes that the celestial bodies, including distant stars and the Milky Way, are composed of gas, but it is a pity that such a brilliant idea has gradually disappeared in the long river of history.
"Hey" Yu Yan smiled: "Although Yu doesn't understand the celestial phenomena, but he has also heard the allusion of worrying about the sky, if according to Xuanye said, the sun, moon and stars float in the sky, then why won't they fall and take a step back, if it really falls, what should it be, isn't it to smash the earth into a hole" Yang Yan looked at Yu Yan with pity, this is really the fearlessness of the ignorant, but Yu Yan still has a cheerful appearance.
In fact, as far as the time is concerned, the example given by Yu Yan is the most criticized part of Xuanye's theory, although there is a reluctant explanation, the sky is high and infinite, the earth is deep and unpredictable, the square is square, and the circle is round.
What this means is that the sun, moon and stars move separately and have their own laws, but they are not convincing due to the lack of observational data.
Several people looked at Yang Yan again, and it was obvious that Yu Yan's persecution had hit Yang Yan's death hole.
Yang Yan smiled slightly: "The reason why the sun, moon and stars do not fall is because the earth where we live is also a round ball, let's name the earth, and other celestial bodies also float in the universe, separated by unimaginable distances from each other, and the universe is boundless, in this case, how to talk about falling is like two drops of water in the ocean, there is no question of who falls and who goes up, maybe there are many stars in the sky that are bigger than our earth."
Contempt, disdain, pity Among the eyes projected, none of them were suspicious or thoughtful, and even Liu Lanzi, who admired Yang Yan the most, cast a regretful look, which was obviously talking nonsense under the lack of reason, if it wasn't for Yang Yan's identity, I am afraid that someone would laugh.
Yu Yan instantly raised his morale and said proudly: "Yu Mou, may I ask, if the earth is round, why don't the people standing on the back fall Do it mean that everyone is standing on the upward side, but so?"
Yang Yan said lightly: "Between things, there is a force of mutual attraction, called gravity, for example, when a peach is ripe, it will fall to the ground, and then it is like throwing a stone to the sky, no matter how strong it is, this stone will eventually fall to the ground, this is because the earth we live on has a gravitational attraction on all objects attached to it."
"This" Yu Yan was speechless for a while, and Yang Yan's list was a common phenomenon, and he couldn't help but look at his cousin.
Yu Xi arched his hand: "What the general said does have some truth, but it is really surprising to argue that the earth is spherical, and the ancient sages have never said this, I don't know if the general can cite empirical evidence."
Yang Yan asked rhetorically: "Yu Jun is proficient in celestial phenomena, he must have observed a lunar eclipse, during a lunar eclipse, the appearance of an arc-shaped light and dark boundary on the lunar surface can prove that the earth is round, because the shadow of the earth blocks the moon, the moon is also a circular sphere, revolving around the earth, when the moon runs to the shadow part of the earth, the area between the two will be blocked by the earth because of the sunlight, so it seems that the moon is missing a piece, and at this time, the sun, the earth, and the moon are in the same straight line."
Let me give you another example, I don't know if you have ever seen a ship on the sea, if you pay close attention, the sail always appears first, and then the hull of the ship when the ship comes, which proves that the earth we live on is spherical. ” "By the way, Yu remembered" Yu Yan suddenly exclaimed: "Once I looked at the ship at the mouth of the Qiantang River in Zhejiang, as the general said, the sail appeared first, and then the hull appeared, if the general didn't mention it, Yu almost forgot about it."
Diao Xie and Cui Wan exchanged an incredible look.
Yu Xi fell into deep thought, he had indeed observed the lunar eclipse, recalling the scene at that time, and his eyes flashed with confusion or doubt from time to time.
Yang Yan nodded secretly, he did not expect people to accept the fact that the earth was round all at once, but hoped to bring thinking, bring doubts, and prompt them to explore and study.
After a while, Yu Xi asked: "The sun and the moon rise and set in the east around the earth, so there is a division between day and night, according to your general, how to explain day and night?"
Yang Yan nodded and said: "Yu Jun said hello, the reason why there is a difference between day and night is that the earth is a rotating sphere, one side faces the sun, and the other side must be night, just as Xuanye said, all the planets were originally gases, and the rotation made the force return to the center, which is called centripetal force, which is compressed into a solid under the influence of centripetal force, and the process of rotation will not stop abruptly, but will only rotate more and more slowly, because the process is extremely slow and unnoticed. ” In fact, Yang Yan's purpose is to open a door for the development of science as much as possible, and try to combine the two philosophical systems of modern and ancient times, take the essence of the present, remove the dross of the ancient, and produce a new ideological system.
Of course, this task is difficult, but if you don't even try, how can you have any chance of success?
The only good thing now is Yang Yan's identity, and everyone dare not ignore his remarks, which makes everyone have reservations, but they will not be ridiculed.
Yu Xi asked again: "There are four seasons in the sky, divided by the position of the ecliptic where the sun is located, and the four positions of the twenty-four solar terms are used as the seasons, if it is not for the sun to rise in the east and set in the west, how can it be divided in this way, and from the perspective of agricultural time, there is nothing wrong with such a division, I don't know how to explain the four seasons in the general's opinion."
Yang Yan said: "The time of day is divided into four seasons, because the earth revolves around the sun, each revolution is a year, and the orbit is elliptical, and the rotation plane is slightly tilted, at different times of the year, the earth is in different positions of the orbit, so different regions receive different amounts of sunlight, more or less heat, so there are seasonal changes and differences in cold and warm. ” Speaking, Yang Yan raised his eyes and swept over the crowd one by one, carefully paying attention to the changes in his expression, basically all of them were at a loss, only Yu Xi seemed to be pondering, so he said: "Say a thousand, ten thousand, astronomy is a pragmatic science, must be based on actual observation as a reference, if Yu Jun is not in a hurry to leave, you might as well stay for a few more days, this will make a pair of astronomical telescopes as soon as possible, which can magnify the stars more than ten times, or even dozens of times to observe, with Yu Jun's ability, see clearly, the reason is clear, you will know that what Yang said is true." “ "Oh" Yu Xi said with great interest: "If this is the case, wouldn't it be a fairy trick Yu Mou will wait and see" 。
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