He Ying's Notes

When you gaze into the night sky, every speck of light tells a story. Many of the starlights we see have traveled for millions or even billions of years. By the time they reach your eyes, the star may have been annihilated. The scale of the universe is far beyond imagination: there are hundreds of billions of stars in the Milky Way, and there may be more than two trillion galaxies similar to the Milky Way in the observable universe. In recent years, astronomy has revealed that the universe is mostly made up of "dark matter" and "dark energy" - they are invisible but dominate the structure and destiny of the universe. All the matter we are familiar with, including the stars and you and me, only accounts for less than 5% of the total mass and energy of the universe. This reminds us that what is known may only be fragments of the truth. Every deep space exploration is expanding the boundaries of cognition. Understanding the universe is also understanding our own place in endless time and space - as small as dust, but unique in being able to ask these grand questions. Maintaining curiosity about the unknown is the source of infinite broadening of human horizons.