Science

The Arecibo Radio Telescope in the United States used to be the largest radio telescope in the world, with a diameter of 350 meters. As the most powerful radio telescope ever built, scientists have achieved many scientific results with the radio Arecibo radio telescope in the past decades

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

Theoretically, life can take many different forms, such as silicon-based life, sulphur-based life, carbon-based life, amino-life, hydrogen-based life, etc. However, so far we only know that life exists on earth, and all known life, including us humans, is carbon-based.

In a good night sky, we can always see a sky full of stars and it seems to us that the whole universe is in full view. In fact, the stars we see in the night sky are only a tiny part of the milky way galaxy, which is just one of the trillions of galaxies that exist in the observable universe.

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

The law of conservation of momentum means that the total momentum of a system remains constant when it is not subject to external forces or when the sum of the vectors of external forces is zero

Scientists using modern observation equipment have determined the size, position, distance and other data of most of the objects in our galaxy

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"

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

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.