"universe"

The reason we don't see time travelers is actually because they are not in our timeline

Below the solar system, there is a star system labeled "alpha Centauri".

In theory, when a civilization develops into a civilization that can cross the stars, there is basically no risk of extinction

If we make the space station in space into a ring and let it rotate, then the humans in it will also feel the "centrifugal force" to "push" themselves towards the outer wall of the space station

NASA's Jet Propulsion Laboratory's Near Earth Object Research Center has such a database, which is called the "Fireball Database."

Between the Earth and the Moon there exists a much more empty space than imagined, so what can be put down in this space?

The mass of a star cannot grow indefinitely, it can only reach the "Eddington limit" at most, so beyond this threshold, it will soon "eject" the extra material

Since gravity is actually a manifestation of gravity, and the magnitude of gravity is proportional to mass, for those objects with smaller masses, their own gravity is smaller

The universe is so unimaginably large that even if humans were able to travel at infinitely close to the speed of light, they would not be able to penetrate its mysteries. Fortunately, the speed of light is not the speed limit of the universe, so it is entirely conceivable that in the distant future, humans may somehow be able to escape the shackles of the speed of light.

If someone asks the question, are humans alone in the universe? I believe that most people would answer in the negative. In fact, the scientific community also generally agrees that there are a large number of intelligent civilisations in the vast universe, some of which may even be far ahead of our civilisation, and in order to better describe the technological level of intelligent civilisations in the universe, scientists have also proposed the concept of "Cosmic civilisation levels".