Moonlight kisses the waltz

"stand up!"

"Hello teacher!"

Lin Yu walked into the classroom with a small bag and a book in his arms, and nodded to everyone, "Students, please sit down."

He scanned the situation in the classroom - all the students in class 1 of junior high school sat down in their seats and looked at him seriously with their small faces raised.

Lin Yu smiled slightly, took out a laser pointer from the small bag, and waved it at the students.

"In today's class, I will take you to do experiments." Lin Yu said, "This is different from the experiments you usually do in the past. It may be a little difficult. I will try to explain it to you in simple language."

The eyes of the students lit up instantly.

Compared with the boring courses, they obviously prefer the experimental class, let alone the experimental class taught by Dr. Lin himself.

"First let's look at a hypothesis."

Lin Yu picked up the chalk on the podium and drew a huge rectangle on the blackboard.

"Please imagine that this is a pool of water." Lin Yu tapped the lower left corner of the rectangle with a chalk, "If I throw a stone here, what will happen?"

"The surface of the water fluctuates!"

"Water moves!"

"It's not mirror-like water anymore."

The students scrambled to answer, saying roughly the same thing.

Lin Yu nodded: "That's right, there will be water waves. I believe that everyone will try it when they see a pond or a small pool in their spare time, so is there any student who would like to draw me the appearance of water waves?"

A girl volunteered and raised her hand. Lin Yu greeted her, and she ran up to the podium, took the chalk from Lin Yu, and carefully drew several circles of water waves from the inside to the outside.

"Very good." Lin Yu's voice was gentle, and he pointed to the lower right corner of the pool, "Then if I throw another stone here, what will happen to the water?"

The girl continued to draw circles in the lower right corner, and she stopped after drawing a few circles.

——The two circles of water waves are about to meet together.

The whispers of the students came from below.

The girl looked at Lin Yu worriedly, "Mr. Lin, how do you draw this?"

Lin Yu said, "Have you ever observed what happens when two water waves meet?"

Some students in the classroom shouted: "I remember, they will be mixed together and affect each other."

Lin Yu immediately said, "Is there a rule?"

"Uh...this..." The student hesitated.

Another student stood up and said, "There is a pattern, I have observed it."

"Come here and draw." Lin Yu handed him a piece of chalk.

The students ran up to the podium and drew something like wavy lines.

Although not very accurate, but the general meaning is correct.

Lin Yu nodded and asked the two students to return to their seats.Pointing to the water waves and wavy lines on the blackboard, he said: "When two waves meet, they will have a similar effect. In physics, we call it 'wave interference' in a more professional way. "

After speaking, Lin Yu's index fingers intersected in the air, forming a "X" shape.

He said: "The one just now is a wave that you can see with the naked eye in daily life. Now let's look at a wave that is not easy to notice."

He put down the chalk in his hand, looked around the classroom, and said loudly: "Does any student have a knife and a ruler? Can you lend me some."

The student closest to him produced a knife and ruler from a pencil case.

"Teacher Lin, here."

Lin Yu took the knife and ruler, took out a ticket from his pocket, and cut two very thin and close slits on the dark back.

He explained the operation just now to the students, and then asked: "If I shine a light on these two gaps, what will they reflect on the blackboard?"

"Two lines!"

"Two parallel lines!"

The students' responses were roughly the same.

Lin Yu smiled. He turned around to clean the blackboard, and then motioned to the students on both sides of the classroom to draw the curtains and turn off the lights.

The whole classroom went dark in an instant.

Lin Yu fixed the ticket with two slits on the table, then stood behind the table and turned on the laser pointer.

The red laser penetrates the black ticket and hits it on the blackboard.

There was a sound of breathing in the classroom.

"Ah...this..."

"Aren't they parallel lines?"

Displayed on the blackboard are many black and red lines, some wide and some narrow.

"This is a derivative stripe." Lin Yu said, "Everyone think about what I said just now. Does this look like a pattern of water waves mixing and hitting the wall?"

Some students who reacted a little faster answered immediately: "So light is also a kind of wave!"

"Very good." Lin Yu praised the student, and at the same time said seriously, "But you can't simply regard light as a wave. We are currently limited by field experiments, so we can't show you other situations. Under another observation condition , the light does form two parallel lines on the blackboard."

This time it was Zhang Yu who responded the fastest: "So, light is both a wave and not a wave?"

"The wave-particle duality of light." Lin Yu put away the laser pointer, and the derived stripes on the blackboard disappeared immediately, "The conclusion of this experiment is that light is both a wave and a particle, and its state is the superposition of the two special types." .”

The lights in the classroom were turned on again.

"This experiment will be explained in detail when you are in college. I won't talk too much now, for fear of misleading everyone." Lin Yu walked up to the podium and looked at the students, "Please keep a rational attitude and continue studying , the existing theorems and laws may not be completely correct. Just like our world has gone through countless difficult journeys from the earth-centered theory to the heliocentric theory. Remember, you must always have a heart of exploration and the courage to question, And learn to observe life and think from time to time.”

There were sporadic applause from the audience, and then the applause became denser and louder, accompanied by the light in the eyes of the students.

At the end of an experimental class, Lin Yu walked out of the classroom of Class 1, Junior Three.

There were footsteps behind him, Lin Yu turned around, and saw Zhang Yu running towards him and stopping less than one meter away from him.

"Mr. Lin, don't worry, I will definitely study hard." Zhang Yu's expression is very determined, "I will be admitted to the same university as you, and then go to graduate school and Ph.D.... as long as my ability can support me As long as I keep going, I will keep learning."

Lin Yu was startled for a moment, but when Zhang Yu finished speaking, he smiled gratifiedly and reached out to pat Zhang Yu's head.

"Okay." Lin Yu said softly, "But don't push yourself too hard, just do your best without regrets."

……

Lin Yu went down the stairs to the first floor.

There was a burst of piano sound from the direction of the music classroom. The sound was lively and lively, accompanied by the cheerful singing of the students.

"I'm from Alabama, with my banjo;

Going to Louisiana to find my love.

It rained heavily at night, but the weather was still dry.

My heart is cold in the hot sun, Susannah, don't cry. "[1]

Lin Yu walked to the classroom window and saw Luo Xingu sitting beside the upright piano, and several girls clapping and singing with smiles on their faces.

The girls had sharp eyes, and immediately spotted Lin Yu outside the window, shouting, "It's Teacher Lin!"

Luo Xingu also stopped playing, and turned to look out the window.

The window between the corridor and the classroom was very low. Seeing this, Lin Yu jumped over the window frame with his hands and jumped into the classroom.

The students cheered.

One of them raised his hand jokingly: "Mr. Lin violated the rules and opened the window, I'm going to report to Director Huang!"

Lin Yu ran over in two or three steps and said, "Don't, don't, please spare me, let Teacher Luo teach you how to sing and play the piano again."

Luo Xingu chuckled: "A Yu used me to please the children."

The students retorted: "We are not children!"

"That's right, we're all in junior high school."

Lin Yu quickly blinked at Luo Xingu, which meant—play the piano to change the subject.

Luo Xingu smiled lightly, stretched out his right hand and pressed a few simple notes on the keys.

"Ah, this is Little Star," said one student.

Another student rubbed against Luo Xingu, looked at the keyboard and said, "The singing method taught by Teacher Luo just now. Dodososolalaso——"

"Little Star" is a very simple song. Even if there is no piano teaching, teachers in general school courses will sing along with it.

Lin Yu walked to the piano, and Luo Xingu suddenly added the melody with his left hand, and at the same time, the rhythm of his right hand suddenly changed from quarter notes to sixteenth notes, and a series of scales flowed out from under his fingers. [2]

"Wow." The students gathered together.

It is obviously still the main theme of Little Star, but the difficulty and skills have been multiplied countless times.

This is the changing magic of the piano and the infinite charm of music.

After the song was over, a bolder student grabbed Luo Xingu's arm and said, "Mr. Luo, can you stay and be our music teacher?"

Immediately someone agreed: "Yes, yes, let's go talk to Director Huang and give you a higher salary."

"We'll all learn from it."

Lin Yu didn't expect the students to be so enthusiastic, and he quickly searched for vocabulary in his mind to smooth things over.

Suddenly he heard Luo Xingu say: "Don't worry, I will come again next year."

Lin Yu was startled, and couldn't help but look up at Luo Xingu.

He never expected that Luo Xingu would make such a promise.Originally, Luo Xingu was able to accompany him this time, which made him very satisfied.

The students were a little disappointed, but they somehow guessed that Luo Xingu could not really stay, so they continued to ask: "Will you come at this time next year?"

Luo Xingu nodded and replied: "Next year when the first snow falls on Mount Huai, I will be back. See you soon."

Some students breathed a sigh of relief and clapped their hands happily, while others had red-eyed circles.

"But I'm graduating next year," said the girl.

Luo Xingu beckoned for the girl to come to him.

The girl's eyes were filled with tears, and she walked to Luo Xingu's side as she said.

Luo Xingu took out a pen and paper from his pocket, wrote a few lines and handed it to the girl, then took her hand, and said seriously: "I heard that your voice is very good and suitable for singing a few times today. Learn vocal music. I wrote you the contact information of several famous vocal music teachers in Haidu. I will leave you a letter of recommendation tomorrow. Go back and discuss with your family. Go learn music. Money is not a problem, if you want , I will help you."

The girl was stunned for a moment, and then tears fell down in big drops.

"Thank you, thank you..." She wiped her tears helplessly, "I...I want to go..."

"Okay, don't cry, huh?" Luo Xingu took out a tissue to wipe the girl's tears, and said to the other children, "Everyone stand in line, remember the song we sang at the beginning?"

The students immediately formed a circle as if they remembered something important, with Lin Yu in the center.

Lin Yu was still immersed in the emotion of being happy for the girl and did not recover. He was very surprised to see the students surrounding him.

"Brother Luo?" He called Luo Xingu suspiciously.

Luo Xingu began to play, playing the main tune.

The students looked at Lin Yu with smiles on their faces, and sang, "Happy birthday to you, happy birthday to you~"

"Happy Birthday Song".

Birthday?

Lin Yu's eyelashes moved slightly.

Oh, by the way, today is his birthday.

He hadn't celebrated his birthday for many years, and he almost forgot it.

Luo Xingu actually remembered it better than him, and even organized the students to sing birthday songs to him.

He looked up at Luo Xingu's profile, the light refracted from the snow outside the house illuminated the metal rollers of the piano, and his sweetheart was bathed in the sun, warmer than the scorching sun in midsummer.

At the end of the song, the students cheered.

Amidst the cheers, Lin Yu saw Luo Xingu turn around and look at him.

"Ayu, happy birthday."

The author has something to say: thanks.Thank you for your support.

[1] Original song "Oh Susannah".

[2] Here Luoxingu plays Mozart's "Little Star Variations", but it should be noted that the "Little Star" we often hear on the market is a simplified version of Mozart's piece, not Mozart's "Little Star" variation The bomb was expanded.The title of this "Variations" is very misleading.

※The description of "Young's double-slit interference experiment" in this article is my understanding of quantum mechanics and the experiment itself based on my own learning, and does not represent the official theory.If you are interested, you can search by yourself. There are many more professional experimental videos on the Internet.