The earth was born some 4.55 billion years ago, and over that long period of time, life on earth has gone through a process from nothing to something, from simple to complex, and eventually evolved into humans with higher intelligence.

From the known laws of nature, the best way for a species to survive and continue better is for its population to keep spreading outwards, thus effectively reducing the risk of extinction. Since the earth has a limited carrying capacity as well as a limited habitable time, it is necessary for humans to plan for spreading to other planets.

In fact, modern humans are already making initial attempts to leave the earth, and we are optimistic that, as technology continues to improve, sooner or later humans will be able to move beyond the earth and, step by step, spread deeper into the cosmos to become an advanced civilisation spanning the galaxy. How long will it take for humanity to achieve this goal? 10,000 years should not be enough, but if it is 100 million years, that should be more than enough.

Let's not forget that the milky way is a huge galaxy with hundreds of billions of stars, and known observations suggest that even a conservative estimate suggests that there are more than 300 million rocky planets like earth in the galaxy that lie in the habitable zone of stars, and among them, many are hundreds of millions or even billions of years older than earth.

So a reasonable speculation would be that life should be widespread in the galaxy, some of which is even older than life on earth, and this would mean that there should be a number of intelligent civilisations in the galaxy that are older than us humans, and whose technology could be hundreds of millions or even billions of years ahead of humans.

If that were the case, then these ancient intelligent civilizations would have long since developed into advanced civilizations spanning the galaxy by now, and even if we humans were unable to discover them, they would have come to visit earth, yet as far as we know, this has not happened.

Why have no advanced civilisations visited earth? There is no definite answer to this question, and people can only speculate about it. One of the hypotheses is that advanced civilizations may not be interested in the earth or in humans on it at all, and that perhaps humans are just ants in their eyes.

The idea is that the earth is undoubtedly the most special and precious planet in the universe for humans, because its natural conditions are close to perfect for human survival, and it is the only home for humans in the universe.

For advanced civilisations, however, the natural conditions of the earth are not attractive to them, because after all, it is a necessary skill for advanced civilisations to be able to survive in space for a long time without the restrictions of the planets. "In their eyes, earth is just an ordinary "Big rock", which is everywhere in the universe and has no value for exploration.

One might ask, how is it that the earth is not worth exploring when there are all kinds of life on it, and there are also humans with higher intelligence?

Intelligent life is rare in the universe, and perhaps it is just wishful thinking. As mentioned earlier, there are hundreds of millions of planets in the galaxy that have the natural conditions to nurture life, so it is a reasonable assumption that life has evolved on many planets, and even on a number of them.

The idea is that the path to "Intelligent life to advanced civilisation" May have been so fraught with difficulties and bottlenecks that a large number of intelligent beings in the galaxy became extinct due to the deterioration of natural conditions on their home planets before they could develop into advanced civilisations.

In this case, only a very few intelligent beings in the galaxy will eventually emerge, and there will only be a handful of advanced civilisations in the entire galaxy, while the rest will either have disappeared from the universe or be in a "Primitive stage" Where they cannot leave their home planet.

If this is the case, then humans are undoubtedly a "Primitive civilisation", and apart from humans, there are many other "Primitive civilisations" In the galaxy that are similar to humans. In the eyes of the higher civilisations, "Primitive civilisations" Like humans are just like ants, they already know enough.

It is true that we humans can reach any place on the surface of the earth, but there are still many areas on the surface of the earth that humans have seldom ventured into, and if we have to go all the way to a place that does not interest us in the slightest to visit a group of ants that we are used to, then i guess no one would want to go there.

By the same token, distances in the universe are often measured in light years, and even for advanced civilizations, travelling such a long distance would be exhausting, so it is unlikely that they would come all the way to visit earth without the right reason. When we humans are in a hurry, we don't usually stop just because there is a colony of ants on the side of the road.