We can even reasonably speculate that there are some aliens in the universe who appeared in the universe earlier than humans, and their technological level is likely to be more advanced than humans. They already have the ability to travel between stars, and if If that was the case, then they should have come to Earth long ago, but as we know, it didn’t happen.
Why have aliens never come to Earth? For this question, people have put forward all kinds of speculations, some of which can be described as brain-opening, while others seem simple and reasonable. For example, there is a simple view that the reason why aliens have not come to the earth may be that they have encountered the same problems as humans. What problems? To put it simply, it is five words: a long distance.
When we describe a large distance on the surface of the earth, we usually use the unit “kilometer”, but when describing the distance of celestial bodies within the solar system, kilometers are inconvenient, so we usually use the average distance between the earth and the sun The unit of distance, also known as the “austronomical unit”, is approximately 150 million kilometers.
If we expand the scope to the vast space outside the solar system, that astronomical unit is not convenient. For example, the nearest star to us, Proxima Centauri, is about 266877.36 astronomical units away from us. At this time, we will It is necessary to use a larger unit of distance – “light year”. One light year is the distance that light travels in a straight line for one year in the vacuum of the universe, and its value is about 9.46 trillion kilometers. A simple conversion shows that Proxima Centauri and my The distance is about 4.22 light-years.
Although we are accustomed to the distance unit of “light year”, the reality is that for us humans, even a distance of 1 light year is out of reach.
So far, the fastest man-made object is a detector named “Parker”, whose peak speed can reach 200 kilometers per second. At this speed, it takes about 1500 years to fly 1 light-year, but this It is a solar probe, and a large part of its speed comes from the help of the sun’s gravity. Therefore, to understand the true ability of human beings to cross the universe, we have to look at those probes that are expected to fly out of the solar system.
As the farthest man-made object from the earth, the “Voyager 1” probe has flown about 23 billion kilometers so far, and its current speed is about 17 kilometers per second.
This speed can be said to have reached the acme of modern human beings, because it has continuously used the “gravitational slingshot” of Jupiter and Saturn during its flight, even if a similar probe is launched with the current spaceflight capabilities of human beings. When it reaches where Voyager 1 is currently, it will also be traveling at about the same speed as Voyager 1.
Under the influence of the sun’s gravity, “Voyager 1” will continue to decelerate in the future. Even if the sun’s gravity is not considered, it will take about 17,600 years to fly a distance of 1 light-year, and at this speed , it will take about 74,300 years to reach Proxima Centauri, which is 4.22 light-years away.
However, Proxima Centauri is just the closest star to us, and according to the current observation data, whether there is life near Proxima Centauri is a huge question mark, so if humans want to visit the planet where aliens live, they must go farther. How far is it?
We must know that the proportion of planets suitable for life like the earth in the universe is not much, and in the 4.55 billion years of the earth’s history, intelligent creatures have only appeared once, so a reasonable guess is that where the aliens live The planet is likely to be very far away from us, it may be hundreds of light years, or it may be thousands, tens of thousands of light years, or even farther…
It can be seen that in the vast universe, human beings can be said to be struggling. It is no exaggeration to say that in the foreseeable future, even if it is going to the star system closest to us, human beings will not be able to do it, let alone visit A planet where aliens live.
Some people may say that with the passage of time, future humans can develop more powerful technologies that can make spaceships fly at speeds close to the speed of light, and even develop technologies such as “warp drive” and “wormhole traversal“. “Such superluminal technology.
However, this is just a beautiful imagination after all. Starting from the actual situation, these technologies are all illusory, and no one knows whether they can be realized. Perhaps a cold reality is that these technologies cannot be realized at all, or to be realized. , It takes an extremely long time, so that until the human civilization disappears in the universe, these technologies have not been realized.
Yes, this is the problem encountered by human beings. For the same reason, aliens have never come to the earth, or it may be because they have encountered the same problems as humans. Perhaps at this time, an alien on a certain distant planet The aliens are also thinking: “Why haven’t aliens visited us?”
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