Uptown Planetarium, the live broadcast room of the Astronomical Summit.

“…… So Mr. Gan Chongzhi, as the discoverer of the asteroid, why did you choose the word 'year' to name it? ”

"I've explained this many times."

Asked this question again, Gan Chongzhi, who is over 70 years old, was a little helpless and tired: "First of all, of course, because the time it reaches the maximum perigee, according to calculations, it happens to be at the junction of the old and new years, which is also the 24 o'clock of our Chinese New Year's Eve. ”

"What else?"

"The second point is that the meaning of the asteroid to humanity as a whole is like entering a new epoch. This is the first time that human beings have been in such close contact with other ancient planets, and the mineral components we have grabbed from the planets will help human beings to understand the universe more deeply, and even discover the origin of the universe and the origin of the earth. ”

"I heard that the probes sent by various countries have returned to Earth, what are the research results?"

"This ......"

Gan Chongzhi's face turned ashamed: "It's a pity that all the detectors failed and couldn't return. We all underestimated the level of storm activity on the surface of the asteroid, which was much worse than what the Webb Space Telescope observed, and our calculations were wrong. ”

"Have you found the cause of the error?"

"Still looking."

The Astronomical Summit has two phases, the first of which is the free exchange of academic results among delegates from various countries.

The second stage is the live interview and answering questions from the audience.

The first phase is over, and now it's the second phase.

The camera in the studio is cleverly pointed at the host and the astronomical academician Gan Chongzhi, the discoverer of the asteroid.

And the "year" is suspended above the night between the two, and it is also framed in the lens.

The dreamy and magnificent long tail makes people can't take their eyes off it.

Gan Chongzhi is a little restrained, as a scientific researcher who is accustomed to quiet, he doesn't like an environment with a lot of people, and he doesn't like to appear in the field of vision of too many people and be judged by others.

Especially the host's question is too unnutritious, and he already wants to slip away.

The host also realized Gan Chongzhi's restlessness and hurriedly entered the next link.

"Now let's enter the audience question session, there is a little sister over there who has raised her hand for a long time, so let's invite this audience to be the first to ask questions."

"Mr. Gan Chongzhi, there is one thing we have always been unable to understand:

The previous Hubble Space Telescope was already able to observe galaxies 129-13.4 billion light-years away, far exceeding the solar system. However, we only discovered the planet Nian this year, and it had already arrived in the solar system when we discovered it...... Excuse me, is there any special property in it that has escaped our observations? ”

"The answer is simple."

Hearing that it was such a low-level question again, Gan Chongzhi smiled reluctantly.

"The distance you provide is Hubble's observation of the star, because the star can provide a lot of visible light and ultraviolet light, which is the wavelength that Hubble can collect.

However, planets do not emit light, so the only way to observe a planet is to use the transit method, which is to determine whether an asteroid has flown in front of it by the change in the brightness of the star, but this method has many drawbacks.

The new Webb telescope, on the other hand, can collect more light at a wider range of wavelengths and is far more observant than Hubble. It was only after the launch of the Webb Space Telescope that humans had the ability to directly observe distant planets, and this is how 'Nian' was discovered. ”

"Thank you for your explanation."

Satisfied, the audience member sat down.

Then the host chose the second audience, the third place, and the fourth place......

Those questions were more amateurish than the other, which made Gan Chongzhi gradually yawn and couldn't help but start to feel sleepy.

Suddenly, a voice came from the audience.

"Mr. Gan Chongzhi, if an asteroid exceeds the Loch limit and is torn apart at its maximum perigee to become the Earth's ring, what will happen to the Earth?"

What is this sand wall problem? Gan Chongzhi raised his head speechlessly, this question was less professional than the previous ones.

The host hurriedly stopped: "This gentleman, please ask questions in order, this round of questions has not yet begun." ”

Su Yunan's arms were numb, and the host just didn't point to himself, so he just pretended not to see it.

Su Yunan seriously suspected that Lao Gao was afraid that he would make trouble, so he greeted the host in advance.

But he couldn't wait, and the live broadcast was over.

"Mr. Gan Chongzhi, have you calculated the Loch limit of an asteroid?" Su Yunan ignored the host and continued to ask questions.

The corners of Gan Chongzhi's mouth rose: "Of course, we calculated. First of all, it is impossible to go beyond its own Loch limit. Because even the largest perigee is 1.5 million kilometers from Earth. Earth's gravitational pull is simply not enough to capture it, let alone shred it. ”

"So the question is, how do you judge its density? And how to judge its quality? ”

"Quite simply, calculate the mass by the degree to which its orbit is disturbed by Jupiter, and then calculate the density by the size."

"So what's the interference amplitude?"

"It's close to zero, which means it's massy, so it's not disturbed by Jupiter when it's close to it. From this, it is possible to deduce its minimum mass. Then we calculate its minimum density according to the minimum mass, and after obtaining the minimum density, we can get the minimum Loch limit value at which it is torn apart by the earth. ”

"So, it's all estimates, right?"

"No one can give a definite answer, but my calculation must be correct, and we can be absolutely sure that the planet is safe."

Gan Chongzhi's answer was very firm and confident, which came from the knowledge he had accumulated over the years.

He can take 100% responsibility for this answer, and he will be responsible for everything that happens.

"Then here's the problem," Su Yunan smiled, "what if the mass of this planet is zero?" ”

"Poof—"

"Hahahaha-"

"Wow-"

There was an earth-shattering laugh in the entire live broadcast hall, and even the host, who was trying to control the instrument, did not hold back.

Except for two people.

One person is Su Yunan.

One is Gan Chongzhi.

"This gentleman, poof...... I'm sorry, I really can't help it," the host tried to be right, but his voice was still trembling because he couldn't hold back his laughter, "We all know that the mass of such a big planet can't be zero, and what you said is very contrary to common sense." ”

After all, it was a live broadcast, so her language was still very restrained, and she didn't scold Su Yunan as mentally ill on the spot.

"Assuming that the mass is zero, according to the gravitational formula, the gravitational force is zero, and it will not be disturbed by other planets. If it has zero mass but volume, then its density is infinitely small, its density is infinitely small, and the Loch limit is infinitely small – meaning it can be torn apart at any moment. ”

The idea is crazy.

And it's full of loopholes!

The host immediately retorted: "Then according to what you said, such an object cannot exist at all." Its Loch limit is infinitely small, and it should have been torn apart by any matter long ago. ”

"It is not shredded because it has zero mass and does not receive any external gravitational influence, which is preconditioned by gravity."

It sounds like a paradox.

Not only anti-common sense, anti-classical mechanics, and even anti-intellectual.

"Sir, it seems that the question you raised does not belong to the category of astronomy," the host warned euphemistically, "We are here in the astronomical venue, please don't ask irrelevant questions and disturb the order......"

As soon as the host's voice fell, Gan Chongzhi raised his head suddenly.

Just when everyone was laughing wildly, Gan Chongzhi felt that his drowsy brain seemed to be filled with energy in an instant, and he was immediately attracted by this crazy possibility.

He likes weird and crazy questions, even if they seem silly, but many new discoveries come from stupid thinking that breaks common sense.

It was also difficult for people to accept that there was no God in this world.

Of course, liking is like, but science is a rigorous science, and Gan Chongzhi must refute the contradictions in Su Yunan's words.

He stood up and replied with a blazing gaze: "Even if it wasn't affected by gravity, wouldn't it have been hit by a meteorite during its flight?" The density is zero, and it should be touched and scattered. And the mass is zero, and all its quanta are scattered in all directions at an infinite velocity. Nothing like this should have existed in the first place! ”

"Academician, you can't use classical mechanics thinking to look at a group of quantum bodies, especially a group of infinitesimally small quanta, which are so small that they don't exist, so they won't collide with any matter that exists."

"You said it yourself, they don't exist. If it doesn't, we should take it out of consideration. ”

Gan Chongzhi seemed to end the debate with one sentence.

However, Su Yunan only smiled slightly:

"Those probes didn't crash, did they?"

Gan Chongzhi's eyes suddenly widened.