Into Unscientific Chapter 132

  Chapter 132 Newton: So love will disappear, right?

  In front of the blackboard.

   After listening to Xu Yun's words.

  Old Su bent down slightly, picked up a small stone from his side, and let go of it after picking it up.

   Just listen to a click.

  The stone fell back to the ground naturally.

   "Gravity."

   Then Lao Su repeated the word with a thoughtful expression:

   "The name is quite interesting, but Xiao Wang, how to explain this heavy word that does not know gravity?"

  Xu Yun thought for a moment, and said the answer he had prepared a long time ago:

  “The heavy word for gravity means the weight of an object.

   That is, any object with mass, no matter how small it is, will generate gravity accordingly. "

  Old Su's eyes went blank, and he replaced the stones with sand grains in his mind for a simulation.

  After accepting this concept, he continued to ask:

   "Then Xiao Wang, where does gravity come from?"

  Hearing this question, the expression on Xu Yun's face couldn't help but become a little more dignified, and he only heard him say:

   "It is rumored that a long time ago, there was a sage named Shi Hao from the Fengling Moon Shadow Sect, who was extremely intelligent since he was a child.

  He discovered that in all things in the world, every object with mass will exert a force on other objects with mass.

  He named this force gravitation, and gravity is a component of gravity on the earth.

  Gravity is vertically downward, so that all objects will fall freely after breaking away from the support. "

   Finish these. .

  Xu Yun couldn't help but look at Lao Su, for fear that the boss would ask another question 'what is the essence of gravity'.

  After all, the essence of gravitation is a concept that later generations have never had a concrete conclusion about.

   Well known.

  Although Maverick discovered gravitation, what he discovered was actually the mathematical definition of gravitation, not the physical concept of gravitation.

  The answer to the concept of physics will not be further understood by the world until Einstein put forward the theory of relativity:

  The essence of gravitation is the curvature of space—or in other words, it is not only space that is curved, but four-dimensional space-time.

   For the theory of relativity.

  Space-time is a whole, described in terms of physics, flat space-time is called "Minkowski space".

  Bending means that the metric of the flat Minkowski space has changed.

at the same time.

  The general theory of relativity believes that it is the mass of matter that makes space-time bend.

  The object runs along the shortest route in four-dimensional space-time (geodesic motion), and its motion is in the form of universal gravitation.

   Let's take Xu Yun as an example.

  Xu Yun landed.

   Maverick said:

  Oh, this is because the gravitational force of the earth pulled Xu Yun to the ground.

  Einstein said:

   No, it is the mass of the earth that bends the four-dimensional space-time around the earth, so Xu Yun fell down.

  Xu Yun (called a test particle in physics terms) fell from the tree. From the perspective of four-dimensional space-time, Xu Yun walked the shortest distance from a certain point on the tree to a certain point on the ground at a certain moment.

   That is, Xu Yun is moving according to the four-dimensional geodesic line.

  The projection of this four-dimensional geodesic movement in three-dimensional space is the trajectory of Xu Yun falling from the tree.

   Therefore, in later generations, the explanations of universal gravitation in the three mechanics are also completely different.

  In Maverick's classical mechanics, it is believed that gravity is a basic force produced by mass.

  Einstein's general theory of relativity believes that gravity is caused by the curvature of space-time.

   According to quantum mechanics, gravity is produced by the exchange of gravitons between matter.

  Which of the above views is right or wrong is unknowable, and it is still being debated today—"Science" is celebrating its 125th anniversary in 2018. also classified the question as one of the 125 most challenging science problems.

   That's right.

  Same as bicycles, it is such a problem that junior high school physics will mention, and today's scientific community still has no specific conclusions.

   Among the above three points, the qualitative range of classical mechanics to gravity is relatively limited, and classical mechanics is not even used in many cases.

  Therefore, some people always complain that the general theory of relativity negates classical mechanics, which is actually a very rascal statement.

  Even in a novel written by Xu Yun in his previous life, the protagonist traveled to see Mavericks, and some people commented, “Why are you looking for Newton, classical mechanics is just nonsense”.

   Actually.

  The way to judge whether classical mechanics is right or not is actually very simple—just look at whether it has practical value.

  It allows you to build airplanes, drive tanks, build tall buildings tens of meters or even hundreds of meters, and dive deep into the water.

   can be used in various fields of our macro world, so it is very successful.

   At least in the macro world that we can see now, you can absolutely believe it.

   Remember that pendulum experiment:

  Swap the pendulum into a beheading knife and let it out.

   Then put the neck at its original position by 0.01 cm, do you dare to do it?

  Anyway, Xu Yun dared to do it, and he did it, but he used an iron ball the size of a human head.

   Compared with classical mechanics, relativity and quantum mechanics discuss a broader category.

  That is to say, the high-speed microcosm, and it is a matter of ten to the eighty or nine powers at every turn, so classical mechanics is not very easy to use.

all in all.

  The three have their own fields of adaptation, and classical physics is still strong and necessary in life.

  Considering that during the Northern Song Dynasty, it might be possible to understand the microcosm, but what about the theory of relativity and quantum mechanics?

   Unless old Su can recite poems until he is one hundred and thirty years old, it is impossible at all.

   Therefore, Xu Yun's idea is to discuss gravity in the category of classical mechanics, and to impart knowledge according to the basic framework of classical mechanics.

  The line of sight returns to reality.

  Maybe it is because there is no intuitive concept of gravity.

  After listening to Xu Yun's explanation, Old Su didn't go further into the origin of this 'force'.

   Instead, there was a whole new wave of doubts.

  I saw him open his palm, put it next to Xiao Zhao and wave it, then looked at Xu Yun:

   "Xiao Wang, according to what you said, there is a gravitational force between objects.

  Then I'm so close to Xiao Zhao and Xiao Li, why didn't I notice any attraction? "

  Xu Yun looked up at Xiao Li and Xiao Zhao who were a little confused, and explained with a smile:

   "Master, according to what Shi Hao said, gravity is the weakest type of force in the world.

  The force is hardly perceptible, even less than a summer mosquito bite, so it's normal that you don't feel it. "

  After hearing Xu Yun's explanation, Lao Su hadn't responded yet, and Xiao Zhao, who had been silent all this time, couldn't help but speak:

   "My lord, since this so-called 'gravity' is too small to be noticed, how do you know it actually exists?"

  Xu Yun immediately cast an approving look at this fan, and then he pointed to a assembled simple prop beside him and said:

   "Of course it depends on this."

   This set of props is about 40 to 50 centimeters high, and it is also made with the tools found by Mr. Xie.

  When Old Su was experimenting with chalk, Xu Yun was tinkering with this thing.

   And it can be assembled in a short time, so the material of this prop is naturally not too complicated:

  The main body of the prop is a torsion scale that is different from later generations but has similar functions—yes, a torsion scale:

  The prototype of the modern torsion balance was made by Father Michel of the Royal Society in the 16th century, optimized in the 18th century, and finally finalized as the modern torsion balance.

   But before that, there were some relatively primitive torsion balances in various ancient civilizations.

  For example, the torsion balance invented by Lao Su in the Song Dynasty.

  When Lao Su was supervising the production of the water transport instrument, he designed a classic torsion scale that could be finely calibrated in order to calculate the torque.

  The tool diagram was also drawn by Lao Su in "Shao Shengyi Xiangfa Yao".

   And at this moment.

  This torsion balance is tied to the bracket through a very tough steel wire, and two iron balls, one large and one small, are placed at both ends of the torsion balance.

  There is a small mirror on the steel wire that is not very accurate, but can reflect normally.

   That's right.

   See here.

  The physics teacher is not mad at the classmates who must have guessed it.

   The experiment that Xu Yun will carry out this time is the famous experiment of later generations.

  Cavendish Torsion Balance Experiment.

   I've been coding for almost 12 hours, I can't hold it anymore, let's add a normal chapter first, there are more tonight, at least 6000 words.

   By the way, are there any relatively small snacks? I asked once before, and I didn't think they were as delicious as I expected.

  (end of this chapter)

Chapter end