Science

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

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

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

It has long been discovered in practice that the phenomenon of "gravitational time dilation" does exist

The solar system is a system of celestial bodies kept in motion by the sun's gravity, which means that all bodies within the effective range of the sun's gravity are part of the solar system, so by this definition, how large is the solar system?

There is a view that the reason why the Earth looks round is because of the role of the Earth's oceans, which simply means that a large amount of seawater has "filled in" the undulations of the Earth's surface.

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

Earthquakes are a common natural phenomenon. On average, millions of earthquakes occur on Earth every year, except that most of them are so mild that they are largely imperceptible to humans.

In essence, sound is actually a wave generated by the vibration of the object, the sound waves in the air is actually a "longitudinal wave"

Everything we can see in the universe has an internal structure and they are all made up of smaller matter, so what is the smallest matter in the universe?