What is at the center of the universe? It's an essential question that humans have been wondering about for centuries. But the journey toward an answer has been a strange one. If you wanted to know the answer to this question in third century B.C.E. Greece, you might look up at the night sky and trust what you see. That's what Aristotle, THE guy to ask back then, did. He thought that since we're on Earth, looking up, it must be the center, right? For him, the sphere of the world was made up of four elements: Earth, water, air, and fire. These elements shifted around a nested set of solid crystalline spheres. Each of the wandering stars, the planets, had their own crystal sphere. The rest of the universe and all of its stars were on the last crystal sphere. If you watch the sky change over time, you could see that this idea worked fine at explaining the motion you saw. For centuries, this was central to how Europe and the Islamic world saw the universe. But in 1543, a guy named Copernicus proposed a different model. He believed that the sun was at the center of the universe. This radically new idea was hard for a lot of people to accept. After all, Aristotle's ideas made sense with what they could see, and they were pretty flattering to humans. But a series of subsequent discoveries made the sun-centric model hard to ignore. First, Johannes Kepler pointed out that orbits aren't perfect circles or spheres. Then, Galileo's telescope caught Jupiter's moons orbiting around Jupiter, totally ignoring Earth. And then, Newton proposed the theory of universal gravitation, demonstrating that all objects are pulling on each other. Eventually, we had to let go of the idea that we were at the center of the universe. Shortly after Copernicus, in the 1580s, an Italian friar, Giordano Bruno, suggested the stars were suns that likely had their own planets and that the universe was infinite. This idea didn't go over well. Bruno was burned at the stake for his radical suggestion. Centuries later, the philosopher Rene Descartes proposed that the universe was a series of whirlpools, which he called vortices, and that each star was at the center of a whirlpool. In time, we realized there were far more stars than Aristotle ever dreamed. As astronomers like William Herschel got more and more advanced telescopes, it became clear that our sun is actually one of many stars inside the Milky Way. And those smudges we see in the night sky? They're other galaxies, just as vast as our Milky Way home. Maybe we're farther from the center than we ever realized. In the 1920s, astronomers studying the nebuli wanted to figure out how they were moving. Based on the Doppler Effect, they expected to see blue shift for objects moving toward us, and red shift for ones moving away. But all they saw was a red shift. Everything was moving away from us, fast. This observation is one of the pieces of evidence for what we now call the Big Bang Theory. According to this theory, all matter in the universe was once a singular, infinitely dense particle. In a sense, our piece of the universe was once at the center. But this theory eliminates the whole idea of a center since there can't be a center to an infinite universe. The Big Bang wasn't just an explosion in space; it was an explosion of space. What each new discovery proves is that while our observations are limited, our ability to speculate and dream of what's out there isn't. What we think we know today can change tomorrow. As with many of the thinkers we just met, sometimes our wildest guesses lead to wonderful and humbling answers and propel us toward even more perplexing questions.
宇宙的中心是什么 这是一个很重要的问题 几百年来,人们为此上下而求索 但这段探索之旅的结果 却十分奇怪 如果你想知道公元三世纪希腊人 给出的这个问题的答案 你要问的人就是亚里士多德 他所做的 就是仰望星空 相信自己所看见的一切 他想:既然我们在地球上,向天上看 那么地球就一定是宇宙的中心,不是吗? 他认为,宇宙是由 四种元素组成的 土 水 空气 和火 这些元素在一个套层中流动 包裹着一个固体球核 每个浮于夜空的恒心和行星 都有它们自己的球核 宇宙剩下的部分和所有的星星 构成了最后的球核 如果你观察天空随时间的变化 你可以发现这个理论能很好的用来 解释你所看到的变化 几个世纪以来 这就是欧洲 和伊斯兰世界的宇宙观的中心 但是在1543年,一个叫做哥白尼的人 提出了一个不同的模型 他认为 太阳 才是宇宙的中心 这个十分激进的新思想 为大多数人难以接受 毕竟,亚里士多德的理论在人们眼中看来 才符合真实的现象 亚里士多德的理论也更加符合对人类本身的奉承 但是一系列奇怪的发现 让日心说无法被忽视 首先:开普敦指出 行星运动的轨道并不是完美的圆弧或者球型 其次 伽利略的望远镜发现 木星也有围绕自己的月亮(卫星) 完全与地球无关 接着 牛顿提出了万有引力定律 说明了所有的物体都互相吸引 最终 这是使得我们不得不放弃 地球是宇宙中心的想法 哥白尼死后不久,在1580年 意大利修道士 布鲁诺提出 太阳这样的恒星 都有自己的卫星 还有 宇宙是无限的 这个理论推广得并不好 布鲁诺因为他激进的言论被烧死在刑柱上 几个世纪之后 哲学家笛卡尔 提出 宇宙是一系列螺旋体 这些螺旋体被他称之为 漩涡 每个恒星都位于漩涡的中心 随着时间发展, 我们发现星星的数量远多于 亚里士多德所能想到的 随着赫塞尔这样的天文学家发明出 更加先进的望远镜 太阳实际上银河系类诸多恒星之一这个景象 显得愈发清晰 那些黑夜里的印迹 其实是其他的星系 那些都跟我们的母星系银河一样庞大 可能我们离宇宙中心要比想象中遥远多了 在1920年代,天文学家研究星云 想弄明白它们的运动规律 根据多普勒效应 向我们飞来的物体会 呈现蓝移谱 飞走的物体呈现红移谱 但所有观测到的现象都是红移谱 所有星星都在以飞快的速度远离我们而去 这些观测构成了现在被我们称之为 大爆炸理论的证据 根据这个理论 宇宙中的所有物质 最初都来源于一个单一的密度无限高的球体 简单的说 我们所处的这部分宇宙 曾经在中心 但这个理论放弃了”宇宙中心”的想法 因为无限的宇宙根本无法有中心的概念 大爆炸并不只是空间当中的一次爆炸 而很是一次空间本身的膨胀 新的发现表明 虽然我们的探索有所局限 但我们探索和幻想更外面层的宇宙空间的能力 是无限的 我们今天所认可的事实 有可能很快被改变 许多思想家都共同认为 有些时候 人类最狂野的想象 可以引领我们找到奇妙的答案 并指导我们向更加复杂的问题发出挑战