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nebula space galaxy universe stars planets black hole white hole wormhole light-year extragalactic interstellar transcendental science fiction fantasy 瑰丽 壮观 奥妙 探索 发现 未知 神秘 浩瀚 无垠 无限 永恒 循环 往复 交替 更迭 生生不息 origin of the universe mystery of the universe origin of life alien extraterrestrial civilization interstellar travel time travel parallel universe multidimensional space string theory M-theory quantum mechanics relativity black hole theory white hole theory wormhole theory speed of light gravitational wave dark matter dark energy cosmic expansion cosmic contraction cosmic cycle