cosmological constant,

A very magical existence.

If it were Xu Mang a minute ago, when faced with this problem, he would have silently raised his hands to show that he had surrendered. However, just after this minute, he evolved from a mortal to a god of learning, and he understood it in an instant

This thing is the cosmological constant.

at this time,

The other students were quite sympathetic to Xu Mang's experience. They didn't mean to ridicule him. After all, it was so tragic that a terminally ill person had to be humiliated by physics at the last moment of his life.

A male classmate sitting near Xu Mang cautiously said to Xu Mang: "Xu Mang's cosmological constant is a cosmic field strength, a term proportional to the metric tensor."

However

The sound was so quiet that Xu Mang didn't hear it.

"professor!"

"Do you want me to talk about the cosmological constant?" Xu Mang stood up and said seriously: "If you insist on letting me talk about the cosmological constant, I'm afraid it will delay your class time and the students' ability to acquire and enjoy knowledge.

hapiness."

"???"

"???"

"???"

Damn it!

Is this a way of letting oneself go before death?

The thirty or so students in the theoretical physics class present looked at Xu Mang in horror. Could this be a flashback?

The professor also has a tough temper. He has long had a strong opinion about Xu Mang lying on the table all day long. It is not that he is disgusted with Xu Mang's inability to learn, but he has a positive attitude towards Xu Mang's IQ, otherwise

Nor will he achieve so many achievements except physics.

The professor is worried that Xu Mang behaves like a salty fish all day long, which will affect the surrounding students. The most important thing in learning is an atmosphere, and a role model is also needed.

obviously,

Now this atmosphere has been destroyed, and the example has gradually been distorted.

"Can!"

"The next time is for you to talk about the cosmological constant." The professor nodded.

"Then me"

"Can I stand in your position?" Xu Mang said with a smile: "I'm sorry, Professor, I'm used to taking advanced mathematics courses for students majoring in optics."

After Xu Mang's reminder, many people realized that he was actually also a lecturer!

Nima,

It was also reported in September that others were graduate students in dual departments and became a senior mathematics lecturer, but I was sitting in the classroom, listening to the professor's lecture.

They are all human beings, why are they so different?

after,

Xu Mang stood in front of the podium, and a strange yet familiar feeling came back.

"System I want all the contents of the cosmological constant!"

[Identified by the system, the redemption value of all the contents of the cosmological constant is: 1500 (physical skills)]

Holy shit!

Is it so expensive?

However, the arrow had to be fired when it was on the string.

Xu Mang couldn't bear the pain and could only pay 1,500 skill points.

By the way,

Memory mode is enabled.

After all, after spending so many skill points to explain a cosmological constant, why should I remember this knowledge?

"Ahem!"

"If you want to know what the cosmological constant is, then I have to start with Einstein's general theory of relativity." Xu Mang then wrote a field equation on the blackboard, then turned to his classmates and said, "You should know this.

What it is, in this case, is Einstein’s field equations, which describe gravity as the curvature of space.”

The concept of space curvature,

All students present understand that this concept has been verified in the macroscopic universe. Of course, this does not mean abandoning the law of universal gravitation. The curvature of space is just a fine-tuning of Galileo's and Newton's theories.

"This is energy, and this is the shape of space-time." Xu Mang said, "This is an equation based on the static universe, used to calculate the universe."

"but"

"What this equation calculates is a dynamic universe." Xu Mang paused: "You don't need me to explain the dynamic universe, right?"

The students present shook their heads, showing that there was no need to talk nonsense!

"oh"

"Einstein at that time believed that the universe was static and the universe should remain stationary." Xu Mang wrote another field equation, but this time it included a term, the Λ*g_uv universe term.

By the way,

Under this universe term, two wavy lines are drawn.

"Einstein raised his hand and suddenly added something, which is the cosmological constant Λ*g_uv." Xu Mang paused and said silently: "It is an unknown cosmic energy that he imagined."

"As long as a certain value is given, the universe can be kept static and no longer change." Xu Mang continued: "Unfortunately, even if this cosmological constant is added, the calculated universe is still dynamic."

"Later"

"Edwin Hubble discovered that the universe is expanding. How he discovered it and how he proved it, Teacher Xu won't explain too much here." Xu Mang smiled: "Then Einstein felt that he had committed a crime in his life.

The biggest mistake was adding an unnecessary cosmological constant."

this

The professor standing under the podium listened to Xu Mang's science popularization with some surprise on his face.

I originally thought that Xu Mang was just briefly introducing the cosmological constant. Who knew that this guy narrated the past life of the cosmological constant in such a concise and easy-to-understand manner? What a talent!

under

This should be the key point!

I hope Xu Mang can bring some surprises!

The professor knows that the previous introduction is not important, but the content behind it is important.

"However, one of Einstein's mistakes inadvertently brought another unsolved mystery to the world." Xu Mang said seriously: "The cosmological constant has been given the physical equivalent of vacuum energy, that is, it exists in the background of space.

Energy, that is, dark energy.”

after,

Xu Mang was out of control.

From the speculation of dark matter to the overthrow of the Big Crunch theory, from the issue of cosmological constants to the theory of quantum gravity, from the assumption that vacuum has force properties to the theory of inflation.

Xu Mang goes further and further on the road of showing off,

Never looked back.

And the scene gradually began to get out of control.

""

""

""

Is it over?

Is it over or not?

You're so fucking stuck up there that you can't get down, right?

The classmates were going crazy. Apart from being amazed at Xu Mang's profound knowledge, they felt that this was a large-scale show-off scene, and they became the innocent background behind Xu Mang's show-off.

A simple cosmological constant actually involves so many things, and some theories are even unheard of, such as the extremely nonsense theory of the Great Rip of the Universe. What will happen in 90 billion years, you are just talking about it!

at this time,

Xu Mang is talking about quantum field theory in curved spacetime. This concept is used to prove the thermal radiation of black holes proposed by Professor Hawking, that is, Hawking radiation.

But the students all turned their attention to the professor, hoping that he could stop this large-scale pretense scene.

pity

The professor was very interested in Xu Mang's views, and he was listening intently.
To be continued...