"So, the content of two out of the three paintings on the Bronze Gate is already known."
Claudia paused, "But who left these paintings, and who are they meant to be seen by?"
"The most reasonable explanation I can think of is that they were meant to be seen by the 'aliens' in the eyes of the builders."
Li Cheng smirked, "In 1977, NASA launched the Voyager 1 and 2 spacecraft into deep space, both carrying a golden copper laser disc named 'The Sounds of Earth.'
It stored various sounds including Earth's natural sounds, animal calls, music from different civilizations and greetings. To make it easier for 'aliens' to understand, they thoughtfully depicted the spin motion of hydrogen atoms in low-energy states on the surface of the golden disc to indicate the playback direction.
Additionally, it revealed the coordinates of the Solar System using the positions of 14 known pulsars in the Milky Way Galaxy.
