Space travel is difficult, and while it is possible, traveling to other stars is still a challenge, a lot of materials have to be transported to orbit for assembly, and travel can take thousands of years, and even if it survives, 



 

the people on board will have to come from scratch With established civilizations, destination planets may not be as habitable as they appear from a distance, just building a spaceship that can complete the journey is difficult, and interstellar invasion may be unavoidable.

Also, time should be taken into consideration. The universe is very old, life on earth has existed for at least 3.6 billion years, intelligent human beings appeared about 250,000 years ago, but we only invented the technology of long-distance communication a century ago, maybe a huge alien empire The domination of the galaxies spanned several galaxies and stretched for millions of years, and we may have missed them, perhaps on distant planets, where the magnificent ruins faded away.

99% of the species that have ever appeared on Earth are already extinct, and it is easy to think that this is the fate we will face sooner or later. Intelligent life may develop, spread over several galaxies, and then go extinct, repeating the process over and over again. But galactic civilizations may never meet, so maybe all life in the universe will look at the stars and wonder: Where have everyone gone?

 

But there is no reason to assume that aliens are similar to us, or that aliens have similar logic to us, it may just be that our communication methods are very primitive and outdated. Imagine you are sitting in a house and you keep sending messages with a Morse code transmitter, but no one will answer you, you will feel very lonely, maybe we have no way to be detected by intelligent life, we will continue to Go on alone until we find the right way to communicate.

Even if we meet aliens, we may be too far apart for meaningful communication. Imagine the smartest squirrel, no matter how hard you try, you can't explain our society to it. From the squirrel's point of view, a tree is all it needs to know for a complex intelligent life like it to survive, so it will think that human deforestation is crazy, but we don't deforestation because we hate squirrels Yes, we just want resources, neither the squirrel's idea nor the squirrel's life or death is our concern.

A type III civilization may face us with this mentality when it needs resources. They may evaporate our oceans to make it easier to collect the resources they want. Aliens may think a little: wow, there are small Ape-men, they make a lovely concrete building, then crank up the warp drive and leave. But if a civilization wants to wipe out other species, it's more likely to be name and culture than economics.

In any case, it would be more efficient to automate the whole process by creating the perfect weapon, a cosmic probe consisting of self-replicating nanomachines that operate fast and lethally at the molecular level, attacking and destroying in an instant. To decompose an entire planet, just give them four commands.

One is to find a planet with life, the second is to disassemble everything on the planet into its parts, the third is to build new cosmic probes with these new resources, and the last is to repeat these steps. A doomsday machine like this could wipe out all life in a galaxy in a few million years, but why would anyone want to travel light-years just to gather resources or wreak havoc?

The speed of light isn't actually fast, if someone wants to travel at the speed of light, it would take him 100,000 years to cross the galaxy once, and you probably won't be able to fly that fast, maybe some things are more interesting than destroying other civilizations to build empires, one of the fun The concept is the Matrioshka brain, a very large structure orbiting a star, a computer with such powerful computing power could allow an entire species to upload their consciousness and presence into a simulated universe where they could live their entire lives in a A perfect life composed of happiness, never experiencing boredom or sadness.

 

If the device was built around a red dwarf star, the computer could be powered for up to ten trillion years, and who would want to conquer the galaxy or touch other types of life if it could live that way?

There is a problem with all the answers and guesses above: we don't know where the limits of technology are, we may be about to reach the limit, or still far away, and super technology is waiting for us, that will give us eternal life, bring us Go to other galaxies and let us be gods.

One thing we do know is that we don't know anything. Ninety percent of the time since the advent of human beings has been hunting and gathering. Five hundred years ago we thought we were the center of the universe. Two hundred years ago, we stopped using human power as the main source of energy. Decades ago, we created doomsday weapons just because If not, point the weapon at the opponent. In galaxy-scale time, we are still embryos. It is true that we have come a long way, but there is still a long way to go!