Since virtually all the mass of an atom is in the nucleus 既然事实是原子的全部质量集中在原子核，

　　now, there is some amount of mass in the electrons, but most of it is in the nucleus 当然电子也有一定质量，但是可以忽略。

　　how dense is the nucleus? Well, the answer is crazy. 那么原子核的密度是多少？你会觉得不可思议。

　　The density of a typical nucleus is four times 10 to the 17th kilograms per meter cubed. 一般而言，原子核的密度是4乘以10的17次方千克/立方米。

　　But that's hard to visualize. OK, I'll put it in English units. 但数字是难以想象的，那么换作英制单位是

　　2.5 times 10 to the 16th pounds per cubic feet. 2.5乘以10的16次方磅/立方英尺。

　　OK, that's still kind of hard to figure. OK, here's what I want you to do. 当然这还是难以理解的，不如我告诉你怎么做。

　　Make a box that is one foot by one foot by one foot. 做一个各边都是1英尺长的盒子，

　　Now let's go and grab all of the nuclei from a typical car. 然后集合一堆重量相当于一辆汽车的原子

　　Now, cars on average weigh two tons.  车子一般而言重约两吨。

　　How many cars' nuclei would you have to put into the box to have your one-foot-box have the same density of the nucleus? 要在盒子里放多少辆车子的原子才能让这个每边1英尺盒子的密度等同于原子核呢？

　　Is it one car? Two? How about 100? Nope, nope and nope. 一辆，两辆，还是一百辆？都不是。

　　The answer is much bigger. It is 6.2 billion. 答案是不止如此。需要62亿辆。

　　That is almost equal to the number of people in the Earth. 这差不多是世界人口总数。

　　So if everyone in the Earth owned their own car and they don't 所以假设地球上每个人都拥有一辆车，当然并非如此，

　　That would be about the density of a nucleus. 就差不多相当于一个原子核的密度。

　　So I'm saying that if you took every car in the world and put it into your one-foot box, 我的意思是你把世界上每一辆车都装进一个每边1英尺长的盒子中，

　　you would have the density of one nucleus. OK, let's review. 你才得到原子核的密度。我们回顾一下。

　　The atom is really, really, really small. 原子极其渺小的。

　　Think atoms in a grapefruit like blueberries in the Earth. The nucleus is crazy small. 柚子中的一粒原子就相当于地球上的一颗蓝莓。原子核更是出奇的小。

　　Now look inside the blueberry, and blow it up to the size of a football stadium, and now the nucleus is a marble in the middle. 把蓝莓放大到足球场一边大，原子核就是其中央的一颗弹珠。

　　The atom is made up of vast regions of empty space. That's weird. 原子的组成是一大片空间。这是很不寻常的。

　　The nucleus has a crazy-high density. Think of putting all those cars in your one-foot box. I think I'm tired. 原子核有极高的密度。这好比把所有的车放进每边为1英尺的盒子中。我想我累了。