"In other words, the great circle we are in is called a planet?"

"Yes, there are several kinds of planets, and the planet you are on is called a planet. See the big glowing fireball in the back? It is called the star, and it gives you life and hope. ”

Ruan Lin is like an astronomy professor at the moment, tirelessly teaching the basics.

More often than not, he was like a linguist, they didn't have so many unfamiliar words in their dictionary, and Ruan Lin needed to try to combine two phrases that he could understand.

Al hurriedly looked behind the ship, and he saw Amakura Five, the dazzling light emitted was so fascinating.

At a distance of 0.5 AU from the Amakura 5e, Al saw the Amakura 5f close at hand.

He has completely fallen into the galactic landscape: "Is there a planet everywhere out there?" How many of them are there? How big are they, really? ”

Ruan Lin said slowly: "You don't have such a huge number of measurements in your dictionary, in general, they can't be counted, just like the ocean on your planet, how many droplets are there that make up it?"

No one knows exactly how many planets there are, and probably no one has visited them all. Each galaxy can be seen as a disk.

The disk you are in is called the Tencang Five Galaxy, and more broadly, we are in the Milky Way, and it is shaped like an ocean vortex on your planet, and it contains an infinite number of small disks. The bigger one is the Local Group of Galaxies, which has a lot of galaxies that resemble the Milky Way, and of course, our own Milky Way is also among them.

The Virgo Supercluster contains many local groups of galaxies, and generally speaking, the largest unit is the universe that we can observe. ”

Al asked at this moment, "That.. What's bigger? ”

This question was like Teacher Zhong's question to him, and Ruan Lin was stunned.

yes, what's bigger? Are there superclusters of galaxies outside the observable universe? Whether the closed universe model or the open universe model is still inconclusive.

It's possible that the entire universe is a spherical cage with nothing on the outside, like a border in the game, where walls of air block everything and prevent a single step forward.

It is also possible to observe the outer part of the universe or another universe, which is also getting closer.

It's like the Milky Way and the Andromeda Galaxy coming closer to each other, and they will collide and merge in 3.75 billion years.

If an intelligent civilization were born in the outermost part of the observable universe, what would they see?

The heating up of the brain host pulled Ruan Lin back to the display.

"Bigger, I'd like to know." Ruan Lin shook his head.

Al turned his head and looked at Ruan Lin again: "Then you will know one day, I believe you." ”

He clenched his palms, "Thank you, Al." I'll find out someday. ”

Al sat directly on the ground: "We are so small, so insignificant. ”

"A lot of small uncertainties can have an uncertain impact. For example, on your home planet, a snowflake falling on a snowy mountain can cause an avalanche. ”

"Speaking of which, you should also experience what it's like to be outside! wit, stagnate here, we need to get out! ”

As the Titan gradually slowed down, the tail hatch slowly opened, and Ruan Lin pulled Al towards the exit.

The last air available for sound was about to dissipate, and Ruan Lin shouted: "Just jump out!" Don't worry, I'll bring you back! ”

Ruan Lin jumped directly out of the hatch, and he also felt an incomparably wonderful feeling at the moment: it was like the feeling of weightlessness in the moment of skydiving, this weightlessness was always maintained, he felt that he had been falling down, but there was nowhere to land.

Ruan Lin turned his head and looked at Al, who had just jumped out of the hatch, he was still a little uncomfortable, he seemed to be so panicked, Ruan Lin hurriedly turned on the propulsion equipment and rushed to his side.

He put his arm around Al and looked ahead: it was a deep black ocean with countless bright spots.

If there is a human woman beside him, he will not hesitate to confess to her, and the confession ceremony is the galaxy in front of him. All the stars will eventually disappear, but they still shine fearlessly.

Ruan Lin thought of Poincaré's theorem at this moment, that after countless years, all particles in the universe will inevitably return to their position infinitely close to their initial position.

How long is that? It's about the time when a paramecium is moving enough to paint an entire picture of the Last Supper at once.

If the law of increase is the countdown to the death of all things in the universe, then the return of Poincaré is a promise of reorganization of all things, but this promise has taken too long to fulfill.

Al beside him was also distracted, his eyes wandering between the shining stars, and he looked to the right, and the five F of Amakura seemed to be within reach.

The next moment, he looked at his home planet again, and there was no reluctance in his eyes.

He turned his head and looked at the hatch.

Ruan Lin also turned on the propulsion equipment at this time and took him back to the Titan.

On the way back, Al stared at the countless stars outside the porthole, without saying a word.

As the Titan's hatch opened, Al jumped to the ground, and Ruan Lin followed, helping him take off his spacesuit.

The moment the window opened, he said:

"Thank you, Ruan Lin, I don't have any regrets. Ever since the first big thing flew into our planet, I've wondered, what's out there? When you arrived on our planet, I mobilized all my people to meet you, and I want to know the answer from you. My last doubt is now solved, and I can face death.

No matter how much I fantasized about it, I didn't expect there to be so many planets out there, and every time I looked up at the sky, I only knew that something was shining, and they could point me in the right direction on the darkest of nights.

Now I know that one of the bright stars is your galaxy! It also pointed me the way at some point, and it was indeed a brighter star.

I believe that one day my people will be able to know the universe beyond the observable universe as you do. ”

Its two big eyes shed tears, and as if they had met for the first time, it took Ruan Lin's hand and walked towards the beach.

Two Earth months later, Al died in his residence, and Nguyen Lin stood by his side until the last second.

He held Ruan Lin's hands tightly before he died, and left with a smile on his face.

On this day, all his people saw him off. According to their customs, death must be followed by burial on the summit of a snow-capped mountain.

Ruan Lin once again put on a spacesuit for him and buttoned up the window for him.

He wrapped Al's body around his chest and walked to the highest mountain in the afterglow of the setting sun.