4、物质战胜反物质
我们在对称中发现美，但如果不是一个关键的不对称，我们都不可能有机会来欣赏这些美好事物。在粒子碰撞和量子过程中，反物质和普通物质一样，经常被产生出来。事实上，大爆炸产生的物质和反物质数量应该相等——这可不是一件好事，因为每一块反物质都会毁灭等量的物质。因此，大爆炸应该产生一个只有光和能量的宇宙，不存在任何固体、液体和气体。
有可能大爆炸确实创造了足够多的反物质，它们形成了反恒星、反行星、反星系等等，只不过它们存在于宇宙中与我们隔离的另外一块区域。不过几十年来的深空观测表明，这样的可能性极小。
因此，一定发生了某种不对称，让宇宙的演化朝着物质一方倾斜。这种倾斜并不过分——每出现10亿个粒子－反粒子对才会多出一个物质粒子。研究人员已经在物质和反物质的性质之间发现了一种不对称，称之为电荷宇称不守恒，可能已经让事物的演化偏向了我们的物质世界这一边。不过，要把这种微小的偏差转化为过剩的物质，原始宇宙必须经历一段环境极不平衡的错乱时期，现在还没人知道这一过程是如何发生的。（环球科学编译 虞骏）
英文原文：
ATTER OVER ANTIMATTER
We find beauty in symmetry, but without a key piece of asymmetry, we wouldn't be around to appreciate the finer things. In the realm of particle collisions and quantum processes, antimatter is produced as often as ordinary matter. In fact, the big bang should have produced equal amounts of both—not a good thing, because each piece of antimatter would destroy an equal amount of matter. The big bang should thus have created universe of only light and energy, free of any solids, liquids or gases.
It's possible that the big bang did indeed create enough antimatter to create anti-suns, anti-planets, anti-galaxies and the like, and that they exist somewhere in separate pockets of the universe. But decades of observations of deep space make that possibility seem unlikely.
So, some sort of asymmetry occurred that skewed the universe's evolution toward matter. It would not have taken much—just one extra matter particle for every billion particle-antiparticle pairs. Researchers have discovered an asymmetry between the behavior of matter and of antimatter, called charge–parity violation, which could have skewed things to our side of the material world. But for this subtle bias to translate into an excess of matter, the primordial universe would have had to go through a wrenching period of imbalanced conditions, and so far no one knows how that might have happened.
