"universe"

For humans, the universe is too dimensional for us to see the details of its depths for the time being

A rigorous discussion of the unknown is not possible, so it is necessary to narrow down the universe we are discussing to only the universe we can see

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

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

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

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?

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