Science

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

In the evolutionary history of human beings, the gradual increase in brain volume is an important marker

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 the macroscopic world, the solar system is a system of celestial bodies centred on the sun, in which the vast majority of mass is concentrated and the major planets orbit the sun, while in the microscopic world, an atom is a microscopic system centred on the nucleus of an atom, in which the vast majority of mass is concentrated and electrons orbit the nucleus.

The more "nucleons" an atomic nucleus contains, the greater its mass, but scientists have found that the average mass of the "nucleons" of different elements is different

Although ultra-pure water does not exist in nature, humans can prepare it themselves

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

Prehistoric civilization have always been the talk of the town, and it's no wonder - after all, humans have been around for so short a time in the history of the planet that if we were to compress the history of the planet into a single day, then humans would probably only appear in the last two minutes of that day. In the past, there have been frequent claims of the discovery of suspected prehistoric civilization, the most notable of which would be a two-billion-year-old nuclear reactor.

The "four great beasts" of physics actually exist only in thought experiments, and their proposal helps to develop and improve the relevant theories

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