给忙碌者的天体物理学 Astrophysics for People in a Hurry

As Tyson once said, the universe has no obligation to make sense to us.
In 1964, physicist Murray Gell-Mann proposed the existence of quarks, the fundamental components of protons and neutrons. At the time, he believed there were only three members of the quark family, so he borrowed the term “quark” from a cryptic line in James Joyce’s Finnegans Wake: “Three quarks for Muster Mark.” One distinct characteristic of quarks is that they have simple names—a luxury that chemists, biologists, and especially geologists seem unable to afford when naming their own research subjects.
For every billion particle annihilations (leaving behind a billion photons), only one hadron survives.
- These rare survivors ultimately shape the universe, forming galaxies, stars, planets, and even morning glories. Without the minute imbalance between matter and antimatter—1,000,000,001 particles of matter to every 1,000,000,000 particles of antimatter—all matter would have annihilated itself, leaving behind nothing but a universe of pure photons. There would be nothing else—just an eternal void where “Let there be light” is all that remains.
- The fate of quarks and hadrons is also the fate of electrons. In the end, only one in a billion electrons survives. The rest are annihilated with their antimatter counterparts, merging into the sea of photons.
- Without a doubt, carbon-based molecules exhibit far greater complexity and diversity than molecules formed from other elements.
- Just 65 million years ago—less than 2% of Earth’s history— a 10-billion-ton asteroid struck what is now the Yucatán Peninsula in Mexico, wiping out over 70% of Earth’s species, including all the famous super-dinosaurs.
- But what if the universe is eternal—just in a state we do not yet comprehend? Could it be a multiverse where new universes are constantly being born? Or what if the universe simply emerged from absolute nothingness? Or even more unsettling—what if everything we know and love is nothing more than a hyper-intelligent alien species’ advanced computer simulation, created purely for their amusement?
- These philosophical ideas, though fascinating, rarely satisfy anyone. Yet, they serve as a crucial reminder: “Not knowing” is the natural state of a scientist. Those who believe they know everything neither search for nor perceive the boundaries between the known and the unknown in the universe.
- What we do know, what we can say with certainty, is that the universe had a beginning. It continues to evolve. And yes, every atom in our bodies can be traced back to the Big Bang and to the nuclear fusion inside massive stars that exploded over five billion years ago. We are the stardust that came to life, given the mission of self-discovery—and our journey has only just begun.
- Unlike traffic laws, which require enforcement to penalize speeding, the laws of physics do not need authorities to uphold them—because they simply cannot be broken.
- For scientists, the universality of physical laws makes the cosmos remarkably simple. The power and beauty of these laws lie in their omnipresence—they exist whether or not you choose to believe in them. In other words, aside from the laws of physics, everything else is just personal opinion.

正如泰森所说，宇宙本来没有义务让我们理解。
物理学家莫瑞-盖尔曼在1964年提出存在夸克，它们是中子和质子的内部成分，他当时认为夸克家族只有三名成员，所以从詹姆斯-乔伊斯的小说《芬尼根的守灵夜》里一句含义出名模糊的句子‘three quarks for Muster Mark’借用了夸克这个词。这些夸克有一个共同的特征：它们的名字都特别简单——这似乎是当化学家，生物学家，特别是地质学家在给他们自己的研究对象命名时无法做到的事情。
每10亿次的粒子湮灭（由此留下10亿个光子）才会有一个强子幸存。那些孤独的幸存者最终将笑到最后：它们是产生星系、恒星、行星和牵牛花的终极物质来源。如果没有在物质和反物质之间十亿零一与十亿的不平衡，宇宙中的所有物质都将自我湮灭，留下一个由光子组成的宇宙，没有别的——永远是“要有光，就有光”的景象。

夸克的命运，强子的命运，也将成为电子的命运：最终只有十亿分之一幸存下来。其他的电子都和它们的反物质伙伴儿发生湮灭，融入了光子的海洋。

毫无疑问：碳基分子的复杂多样要远超其他元素组合出来的分子结构。

仅仅6500万年前（距离我们的时间不到地球历史的2%），一颗百亿吨的小行星撞击了现在墨西哥的由卡坦半岛，抹杀了超过70%的地球动植物种类——包括所有著名的超级恐龙。

但是，会不会宇宙是永恒的存在，只是它的状态我们尚未认识到呢——比如，它是一个不断诞生宇宙的多重宇宙？或者，如果宇宙仅仅是从一无所有中冒出来的呢？或者，如果我们所知道和热爱的一切都只是一个具有超级智慧的外星物种为了好玩而做的计算机模拟游戏呢？

这些哲学上有趣的想法通常满足不了任何人。然而，它们总能提醒我：“不知道”才是科学家的自然心态。那些相信自己无所不知的人，既没有寻找更没有看过宇宙中已知和未知的界限。我们所知道的是，我们可以毫不犹豫地断言的是，宇宙有一个开始。宇宙在继续演化。而且，是的，我们身体里的每一个原子都可以追溯到宇宙大爆炸，以及50多亿年前发生爆炸的大质量恒星里的核聚变。我们是获得了生命的星尘，然后被宇宙赋予了发现自我的使命——而我们的旅程才刚刚开始。