"Guys, tell me what life is. What is the definition of life? The hostess was the first to ask. Her name is Heigl and she is an astronomer.

Hearing this question, the various scientists present began to talk to each other.

The concept of life, a very magical thing, sounds simple, but in the scientific community, there is no particularly good definition. In some textbooks, life is defined as an object that reproduces and actively ingests energy.

But people seem to be more inclined to use their senses to define whether something is alive or not. Will it move? Will you take in the energy actively? Or will it reproduce?

A car can also move if it can take in energy, but people think that it is a dead thing and does not have the characteristics of life.

An advanced robot, according to the program, can automatically ingest energy, and can even replicate itself, of course, it is not life, this is the opinion of ordinary people.

"An organic, low-entropy body born from nature, which actively absorbs energy and is able to reproduce itself, is called life. Possible...... In a narrow sense, so. This is Yu Yifeng's conclusion, and it is also the opinion of ordinary scientists.

Well, this definition doesn't matter much, and for the time being, I don't think about how the condition of "naturally born" should be characterized. According to this definition, these Martian viruses should be considered life, right?

"Yes, the Martian virus should be regarded as a naturally born life." However, this extraterrestrial life has had a huge impact on scientists......

In the continuous discussion of scientists, Yu Yifeng finally understood what they were talking about, and the main reason for this was because of the Fermi paradox.

Theoretically speaking, human beings can fly to various planets in the galaxy in 1 million, 10 million or even hundreds of millions of years, so as long as aliens evolved tens of millions or hundreds of millions of years earlier than humans, they should come to the solar system and be observed by humans now.

Millions of years, tens of millions of years, this kind of time unit is too long for human beings. But on a cosmic scale, it's just a moment. The age of the universe is more than 13.8 billion years!

Therefore, it is entirely possible that aliens who evolved tens of millions or hundreds of millions of years earlier than humans existed.

However, to date, apart from the inexplicable Noah, humans have found almost no trace of aliens.

In other words, the "Fermi paradox" illustrates the paradox:

1. Aliens exist – scientific inferences can prove that there are aliens that evolved much earlier than humans, and their traces should have appeared in the starry sky, but people have not found them.

2. Aliens do not exist, or in other words, human beings are already the top civilization in the universe.

Now people are mostly inclined to the first view, because of the appearance of the Noah. It must be the crystallization of a super civilization, and it is the boundless kind with a high degree of technology. It's impossible that Noah is born and grown......

Then the question arises, since a higher degree of extraterrestrial civilization does exist. Why have humans never found traces of extraterrestrial civilizations? Why is the universe so empty and cold?

There must be a reason for that!

Now, scientists want to find out why.

"There is an explanation that higher alien civilizations do exist, but in very few of them, and we have not found them."

The host, Haigel, said that she is a middle-aged woman with white skin and a pair of black-rimmed glasses, which looks very solemn and dignified.

"Of course, we also have other explanations, such as: extraterrestrial civilizations deliberately avoid us for some reason and do not let us find out. In other words, the universe is a complete dark forest, and as soon as two civilizations meet, there will be wars, and so on. ”

But these reasons are not sufficient...... It does not fully explain the emptiness and coldness of the universe. ”

With the current astronomical knowledge, no one thinks that the earth is a special planet. The sun and the earth are just ordinary members of the vast universe, without any particularity.

Therefore, some people have begun to study whether there are planets similar to the earth in the Milky Way, and whether there is a more suitable environment for life to survive.

The vast galaxy is about 200 billion stars, and there are countless planets. Earth-like planets must exist, and there are quite a few of them.

The more famous is the Drake equation, designed by the American astronomer Frank? Drake, proposed in the 1960s in the town of Green Bank, could be used to speculate on "the number of extraterrestrial civilizations within the galaxy that may have come into contact with us".

Someone once calculated the number of extraterrestrial civilizations according to the Drake equation. According to calculations, the number of advanced technological civilization planets in the galaxy is at least 40, and up to 50 million!

Asimov, a famous American science writer, once proposed a formula similar to Drake's equation based on his own opinions, estimating that there are about 530,000 civilized planets in the Milky Way. That is, for every 1 million stars in the Milky Way, there may be an average of 18 high-tech civilized worlds.

"But I think these estimates are probably too small. Because we miscalculated the conditions under which life was born......" said Heigl solemnly.

Roman, Thomson, and the others who were sitting on the side all nodded, and it was clear that they had discussed this issue with each other many times.

"We used to think that life was scarce. We believe that the conditions for the birth of life are very harsh, and they need to have water, have enough atmosphere, have a suitable temperature, and so on. ”

"But I didn't expect that there would be life on Mars, although it was only the simplest virus! But it's also life! ”

"Assuming that life is scarce, then how can the solar system have two planets of life? And we don't know if Enceladus and Ganymede have life, or maybe they do? ”

"If life is scarce, a 1 in billions chance, why does the solar system have multiple planets of life?"

All the scientists began to think about Heigel's question. These words also made Yu Yifeng fall into contemplation, assuming that life in the universe is scarce, just like buying a lottery ticket, it is very rare to win once, so why does the solar system win the lottery one after another?

Is it special luck? Or is it something else?

It was a long time before Haigl continued to speak.

"In the simplest explanation, our premise is wrong. Life is not scarce...... It's universal! ”

"Life is universal on every planet. Or rather, much more than we think! ”

This remark immediately caused a huge sensation, even a little subversive, and many scientists immediately jumped in disbelief. Human beings have been looking for extraterrestrial life, and as a result, extraterrestrial life is universal, which is really a bit difficult to accept.

However, Heigel's counter-evidence is brilliant and logical.

Suppose that in the universe, life is rare. So why does Mars, such a shaky planet with no features, have life? In the universe, there are not too many planets like Mars!

Could it be that human beings are so lucky that they can find rare life on any planet?

Therefore, the assumption that "life is rare" is most likely wrong. Therefore, if the assumption is not true, life is likely to be universal.

Although he felt a little puzzled in his heart, Yu Yifeng was stunned that he didn't come up with a better explanation, and he didn't think of anything that could be refuted. To say that "the solar system is very special" and "human beings are particularly lucky" is to lie to themselves.

Is it true that human beings are so lucky that they can encounter a small probability event by finding a planet at random?

Well, life is universal in the universe, perhaps...... It's true! If life is universal, then it is not surprising that the solar system has multiple planets of life.

"Yes, Professor Heigl, your reasoning is very good, and there is a good chance that it will be correct. But to have life is not necessarily to have wisdom. ”

It was the genius of Tesla Research who stood up to speak, Dr. Rimbaud, the young man who discovered Noah's "Beyond Speed Program". He is young and vigorous, and he will not hold back any thoughts, "It is also possible that most of the life on the planet is a low-level single-celled organism and does not possess intelligence. ”

"Yes, you're right." Heigl nodded and said approvingly, "So the next step for us to discuss is whether wisdom also has universality..."