It is reasonable to have a two-way foil for my second-level civilization: in 2050 AD, the sun is affected by unknown influences, and a helium flash is about to erupt! Earth at stake? It doesn't matter, I will make a move! The three-body galaxy, the neighboring star civilization is about to invade? It doesn't matter, I will make a move! In the dark universe, there are disputes among advanced civilizations? It doesn't matter, I will make a move! ...Starting from the controllable nuclear fusion, the protagonist Lu Yongchang opened the interstellar era of human civilization! Aerospace planes, space elevators, energy weapons, antimatter preparations, grand unified theory, curvature navigation, two-dimensional debris (two-way foils)...methane oceans, mysterious species! Liquid ammonia planet, physical fusion!