? Maybe? What do you mean? In other words, it may be positive or negative, which means nothing. So far, mankind has been looking for extraterrestrial civilization for hundreds of years. Except for some UFO incidents with no evidence, I didn't see an alien hair, and I didn't even find a bacterial spore of alien life. But this does not mean that there is no extraterrestrial life or civilization in the universe. If you speak with evidence, you can neither confirm nor deny it now. Let's look again.

So, now all the topics about aliens or extraterrestrial civilization are just guesses. Guess what, you can say that the earth is the first civilization, and you can also say that the earth civilization is not even as good as Mao, but it is still a very low-level civilization of 0.73. The universe is138 billion years old. If there is a 5 billion-year-old civilization, then this civilization is already 8.8 billion years old. How advanced is that? At least it has reached the third level of civilization, and it can already shuttle between galaxy clusters, right?

Even with the civilization of 6.5438+0 million years ago, it is remarkable.

But where are these civilizations? Hubble has now seen galaxies that are more than130 billion light years away, and no hair of civilization has been found. This is the so-called Fermi paradox.

The scientific community has long made some theoretical estimates about the civilization of the universe. Drake equation is the most representative one. This theory was put forward by American astronomer Frank in the last century. Drake. ? Drake equation? It is a formula for quantitative analysis of civilizations, which is used to calculate the number of advanced civilizations that the Milky Way and Hubble volume may be able to communicate with us by radio. The formula is expressed as:

Formula 1: n = ng? Fp？ Ne？ Fl？ Fi. Fc？ Florida

Equation 2:N=R*? Fp？ Ne？ Fl？ Fi. Fc？ L

This formula is verbose, you can search it online if you are interested. I have published such articles before, so I won't take up much space here.

The conclusion of this formula operation is also ambiguous, because there are many uncertain factors, such as FL stands for the duration of scientific and technological civilization, who knows how many years it will last? According to this formula, some people think that there is a great possibility of extraterrestrial civilization in the universe.

There are about 400 billion stars in the Milky Way. If the estimate is optimistic, the Milky Way has at least 654.38+0 million civilizations, accounting for only 25% of the total number of stars. Even if there is only one human civilization in the Milky Way, there will be hundreds of billions of observed galaxies in the universe, while it is scientifically estimated that there may be 10000 ~ 10 trillion galaxies in the universe, and each galaxy has a civilization and hundreds of billions to trillions of civilizations.

In that case, why didn't civilization see it? This is the Fermi paradox. One day in 195 1, Nobel Prize winner and American physicist english? Fermi was discussing UFOs and aliens with others when he suddenly said, Where are they? ?

In a word, a celebrity becomes a classic, which one is a celebrity? Fermi paradox? Origin and core.

There are some implications in this: theoretically, if humans can fly to some planets in the Milky Way in 654.38+million years, then aliens should come to the earth as long as they evolve 6.543+million years earlier than humans, and according to the age of the universe, this is not only possible, but also the civilization of the universe should be greatly advanced. But in fact, no trace of aliens has been found so far, so it can be said that alien civilization does not exist.

So this is a paradox.

After Fermi Paradox was put forward, many scientists responded, and Drake was one of them. Drake equation? Although the number of cosmic civilizations is uncertain, many people still think that there are many, but the distance between these civilizations is too great, and the possibility of contact is zero.

? Fermi paradox? It has been inconclusive for more than half a century. Fermi paradox has been discussed in the scientific community for more than half a century, and there is no conclusion yet.

To sum up, so far, there are several possibilities for extraterrestrial civilization: 1, extraterrestrial civilization has no ability of interstellar travel; 2. Extraterrestrial civilization does not intend to contact with human beings; 3. The earth has been to extraterrestrial civilization, but we don't know it; 4. Civilization does not last long, nor can it develop into an advanced state.

Space-time communication has been expounded many times in the past articles. In addition to the above possibilities, there are several points that make it difficult for extraterrestrial civilization to contact with human beings:

1. Although there are many civilizations at the cosmic level, they are still too rare in the Hubble volume with a diameter of 46.5 billion light years. There are trillions of stars at a distance of millions of light years. If there are only two civilizations, the probability of touching each other is really too small. Even radio waves are difficult to receive;

2. Gamma-ray bursts regularly clean up the cosmic civilization, just like point 4 above. Civilization cannot develop to an advanced level and it is difficult to go deep into space;

3. The cosmic environment is very different, and there are various forms of civilization. The communication way of perception and feeling may be completely unexpected, or we may meet strangers and be unable to communicate.

But space-time communication firmly believes that there is no human civilization in the universe; At the same time, it is believed that during the existence of human beings, it is very likely that we will not be able to discover extraterrestrial civilizations, let alone deal with them. This seems to be a paradox.

Personal opinion, welcome to discuss, thank you for reading.

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