What will be the last problem of human civilization?

This issue has been mentioned in many science fiction novels. When humans know that they are about to become extinct (for example, the sun is dying but is not yet capable of interstellar migration), the last question is how to build a "tombstone" for civilization. It is to preserve and record everything that has been created in human history in some way for a long time (measured in tens of millions of years), so that aliens who visit in later generations will know that such a civilization once existed in the history of the universe. This is a technical problem that is not easy to solve.

The following is a section of the Earth Museum mentioned in "The Three-Body Problem". The idea of ??the museum should be taken from Clark's "Star"

"Initially, it was a quite large research project. The project is to study how to preserve information within the geological time span. The initial standard was one billion years. Ha, one billion years. At the beginning, those idiots thought it was easy. They could build a bunker world. What is this? But they soon discovered that the modern quantum memory is Nake, which is as big as a grain of rice and can hold a large library. The information inside can only be stored for about two thousand years at most. After two thousand years, because of the internal What decays cannot be read. In fact, this still refers to the best-quality memories. According to research, two-thirds of existing ordinary quantum memories will fail within five hundred years. This is very interesting. What he did was the kind of detached thing that only people with a leisurely mind would do. It suddenly became a real issue. Five hundred years has become somewhat realistic. Aren’t we all people from more than four hundred years ago? The government immediately ordered The museum's research stopped and turned to studying how to back up important modern data so that they can still be read at least five centuries later, haha... Later, a research institution was separated from me so that we can continue Research museums, or tombstones. "Scientists have found that in terms of how long information can be preserved, our memory at that time was better. They found some USB flash drives and hard drives from the AD century, and some of them can still be read. According to experiments, if these memories are of good quality, they can store information for about five thousand years; especially the optical disks we had at that time, if they were made of special metal materials, could reliably store information for one hundred thousand years. But these are not as good as prints. Good quality prints, using special synthetic paper and ink, can still be read two hundred thousand years later. But that's the end of it, that is to say, the means we usually use to store information can only reliably preserve information for a maximum of 200,000 years. And they have to be preserved for a billion years! "But it is also an extremely difficult thing. Scholars began to look for information that has been preserved over a long period of time. The patterns on ancient prehistoric pottery have been preserved for about 10,000 years; European caves The murals found here are about 40,000 years old; the carvings made by the ape ancestors of humans on stones to make tools, if they can be counted as information, first appeared in the middle of the Pliocene Epoch, about 250 years ago. Thousands of years. But don’t tell me, I have actually found information left by humans 100 million years ago. Of course, it is not left by humans, but by dinosaur footprints. "The research continues, but there is no progress. Scientists obviously have it. Some conclusions, but in my face I can't say anything. I said to them, it’s okay, no matter how bizarre or outrageous the results you come up with, if there is no other result, we should accept it. I assured them that there would be nothing more bizarre and outrageous than what I had experienced, and that I would not laugh at them. So they told me that based on the most advanced theories and technologies of modern science in various disciplines, based on the results of a large number of theoretical studies and experiments, and through comprehensive analysis and comparison of a large number of plans, they have come up with the idea of ??preserving information for about 100 million years. The method, they emphasized, is the only feasible method currently known, and it is-" Luo Ji raised his crutch above his head, his long white hair and beard waving, looking like Moses who parted the Red Sea, and shouted solemnly, " Carve the words on the stone!"