"There is tension on the surface of the water that allows the water droplets to stay on the surface of the coin. The hand sanitizer dripped into the water droplets, destroying the tension on the surface of the water droplets, and the water droplets that lost the restraint of tension naturally dispersed and flowed onto the table. ”

Da Liu explained the principle of water surface tension and tried to confirm it with experiments, so that people could easily understand it.

After he finished speaking, he looked at Yang Yuping.

Yang Yuping nodded, asked him to prepare for the second experiment, and then returned to the lectern and continued the lecture:

"We have just experimented with coins and water droplets, and we have proved that there is indeed a force that makes water droplets stay on coins.

So, some students may ask, what is the use of this power? And this power doesn't seem strong at all.

"Next, let's use another experiment to show you what the surface tension is for."

As soon as the words fell.

Da Liu and another science and education teacher lifted a rectangular transparent water tank up and began to prepare for the experiment.

"First of all, we fold a paper boat with paper, which classmate stacks the paper boat beautifully? Would you like to do me a favor? Yang Yuping picked up an A4 piece of paper and prepared to hand it to the students in the first row.

Eve glanced around, then took a deep breath and raised her hand, "I'll fold, I'm not controlled today, I promise." ”

When these words were spoken, they caused a burst of laughter from the surrounding classmates.

Yang Yuping had also heard that this little girl was sad because of the fact that she was mentally controlled by the alienated person, so she handed the paper over and said with a kind smile: "Of course, I heard that you are usually very lively, if you don't take the initiative to raise your hand, you will seem to be controlled." ”

Again, the remark caused laughter.

Eve took the A4 paper a little shyly, began to fold it over and over again, and finally folded a crescent boat and handed it back: "Is this okay?" ”

"As long as it floats."

Yang Yuping took the paper boat and put it in a rectangular transparent water tank.

The paper boat floats quietly on the water, and there is no wind in the room, so there is no wind blowing the paper boat.

"The paper boat floats on the water, there is no power, and naturally it does not move, and now we will drop a drop of hand sanitizer on the back of the paper boat and see what happens." As he spoke, Yang Yuping picked up the bottle of hand sanitizer on the table and dripped it into the water behind the paper boat.

The hand sanitizer entered the water, and the paper boat seemed to suddenly move with strong momentum, moving forward rapidly, until it hit the other end of the rectangular water tank.

The rectangular transparent water tank is 1.5 meters long, and the paper boat traveled a full 1.5 meters before hitting the other end of the tank before stopping.

In the military research class, some students were stunned.

Before seeing this experiment, I couldn't imagine that a drop of hand sanitizer could be so powerful.

Yang Yuping held up the hand sanitizer in his hand and said: "A drop of hand sanitizer makes the paper boat move a distance of 1.5 meters. How does this work?

"Could it be that hand sanitizer is a powerful power ingredient? The answer is clearly not.

"The force that pulls the paper boat to move is actually the tension of the water surface.

"Notice the subtle difference between my wording, 'pull', not 'push'.

"In experiments with coins and water droplets, we have shown that there is tension on the surface of water, and hand sanitizer can break the tension on the surface of water.

Similarly, in the paper boat experiment, the hand sanitizer broke the water tension behind the paper boat, and the water tension in front of the paper boat pulled the paper boat forward until the end of the tank.

"If you are still interested in the experiment that water tension can push paper boats, you can try to stick a small piece of soap behind the paper boat on a wider lake, and I believe you can go further."

After doing two experiments, the students in the military research class were all attracted by the content of this lesson.

Water is the most common thing around everyone, but few people observe what kind of power exists on the surface of the water.

Yang Yuping paused, turned the handout on the table to the next page, and continued: "Okay, we have proved the existence of water surface tension through two experiments, and the method of making the paper boat move through water surface tension.

So, what does this have to do with the lesson we're going to teach today?

"Before I started, I mentioned one word, 'spatial tension'.

"Suppose that space, like water, has a tension.

"So, is it possible for us to use this tension to get our 'paper boats' moving? For example, Shenzhou or something. ”

Niu Dazhi immediately raised his hand and said, "I know, stick a piece of soap on the butt of the Shenzhou." ”

"You're so smart." Fang Yuan and the others couldn't help but turn their heads and squint at him.

Yang Yuping was not angry at such ridicule, but said happily: "That's right, if we can discover the existence of spatial tension and influence it, stick a piece of 'soap' on the butt of the Shenzhou, then maybe one day the Shenzhou will really fly because of this 'soap'." ”

After joking, Yang Yuping brought the topic back to knowledge: "Then the question is, what is spatial tension?" ”

He looked at the crowd and saw that the group of students were listening attentively with sparkling eyes, so he continued: "When everyone was in school, they should have taken astrophysics and had a certain understanding of the origin of the universe.

"According to textbook descriptions, the universe was formed by a big bang that occurred about 13.7 billion years ago.

"And the universe is constantly expanding. In other words, the universe started as a point and expanded after the Big Bang.

"Let's imagine that the universe is constantly expanding like a ball, so is the space of the universe flat?

"A long time ago, humans thought that the ground was flat, but in fact the earth was round.

"The universe was formed by a big bang, and it is constantly expanding, and it is conceivable that the space of the universe is not flat, but has an arc.

"Since there are arcs, then space is not fixed, but can be distorted and changed.

"In other words, there is tension in space, and if we can influence this tension and eliminate the tension behind the spacecraft, then the tension in front of us will pull our spacecraft forward like the tension on the surface of the water.

"This kind of drive, which has another name, is curvature drive, which is a technology at the level of time and space.

"According to the level of civilization, this kind of technology has gone far beyond the scope of stellar civilization, and is much higher than the strong interaction force materials."

Hearing this, Fang Yuan finally understood how the magical pull generated by the "Lightning Speed" came about.

However, Yang Yuping then added: "However, so far, we have not experimented to verify the existence of spatial tension."

"Fortunately, Fang Yuan may have already had a spatial tension phenomenon on his body, and when the battle is over, he will have to be tied up to the laboratory for a good study."

When the crowd heard this, they began to laugh again.

Han Youwei also turned her head and whispered, "You must be the professor's favorite guinea pig." ”