Scientists calculate that there are 100,000 extraterrestrial civilizations in the galaxy, but it is not very realistic to reach humans

It has been 13.8 billion years since the universe was born. During these 13.8 billion years, the universe has expanded faster than the speed of light, and its diameter has exceeded 93 billion light-years (93 billion light years, which is an observable space. As for the observable distance, it is still unknown how big the outer part of the universe is).

In this space of 93 billion light years, there are 200 billion large galaxies, of which the Milky Way is only one of these 200 billion galaxies, just like dust. Even such dust has 100-400 billion stars in it.

The solar system is like insignificant dust in the galaxy, but inside this dust, there is a planet called Earth and civilization was born.

In terms of probability, in the entire universe, the probability of a civilization being born in the solar system is one in 800 trillion. Many people do not have this number of probabilities, so let's make a visual comparison. Converted to scientists, the probability of being struck by lightning in human life is one in 13,500, which is trillions of times higher than the probability of a civilization being born on Earth, and is an extremely high probability event.

On the other hand, humans do not have to worry at all and feel that it is impossible to happen a small probability event. The probability of being struck by a meteorite is much smaller than the probability of being struck by lightning, which is probably one in a few hundred million. Even this probability is trillions of times higher than the probability of the universe giving birth to Earth's civilization.

As a result, many scientists have wondered why such an extremely low probability event would occur in such an insignificant star system as our solar system.

Once a scientist used the Earth as a model and took the lowest value to calculate the probability of a planet giving birth to civilization after taking into account various factors. This is the famous Drake formula, which finally concluded that 100,000 extraterrestrial civilizations could have been born in the Milky Way.

If 100,000 civilizations were born in the Milky Way alone, there would be 200 billion galaxies similar to the Milky Way in the observable universe. 100,000 times 200 billion would be a very large number, and there would be 200 million extraterrestrial civilizations. Numerically, the number of civilizations in the universe is very large and appears to be very crowded.

Is this the case? Take the galaxy as an example.

According to Drake's formula, 100,000 civilizations seem to be a lot in the Milky Way galaxy. If distributed in a galaxy with a diameter of 100,000 light-years, a thickness of 16,000 light-years, and 100-400 billion stars, an extraterrestrial civilization will be born in every 100,000-400,000 stars, and its density distribution is about 8,000 light-years.

By calculation, one can be brought back to reality at once, simply because the universe is so big. Although many stars could have given birth to an extraterrestrial civilization, the universe would appear unusually empty if it were spread out over space.

When we look at the Milky Way, 8,000 light years is a very short distance. If placed in the universe, it would be close at hand, but this distance is very far for humans.

Because the speed of light in the universe is unsurpassable, the fastest speed can only be the speed of light. If you know that there are an extraterrestrial civilization 8000 light-years away, and the earth civilization wants to visit it, even if it travels at the speed of light, it will take 8000 years. Throughout the history of human civilization, it has only been a few thousand years, and it is only in the last few hundred years that humans have entered modern civilization.

From this perspective, even if the two closest extraterrestrial civilizations want to communicate across planets, the distance will eventually be an insurmountable threshold that prevents extraterrestrial civilizations from communicating with each other.

At this stage, mankind has to search for another extraterrestrial civilization, not to mention crossing 8000 light years. Even the nearest star system, Proxima, is about 4.22 light-years too far for humans to cross.

Voyager 2, the farthest probe in human flight, is currently about 24 billion kilometers from Earth. At its speed, it will take 17,000 years to fly out of the solar system, and about 70,000 years to reach Proxima. This is the time when Homo sapiens came out of the Grand Canyon of East Africa and established modern civilization on Earth.

For a long time in the future, it will be very difficult and almost impossible for humans to get out of the solar system, let alone search for extraterrestrial civilizations. Some people sadly predict that humans will be locked in the solar system and may not be able to go anywhere.

It could also be the distance. According to probability, even though there may be 100,000 extraterrestrial civilizations in the entire galaxy, human civilization has not yet made contact with an extraterrestrial civilization. Perhaps it is unlikely that human civilization will ever break through the solar system in front of an insurmountable distance in its lifetime, let alone cross the stars in search of another extraterrestrial civilization.

Similarly, if one day an extraterrestrial civilization discovers an Earth civilization, it is not very realistic for them to look for humans in front of a distance of 8,000 light-years. What's more, human beings have been using radio technology only for the last hundred years. Even if the other side receives radio signals, it will be several thousand years later.