（明篇描述不会涉及到群聊，是第三视角种田文。）
永乐三年，七月中旬。
一名身穿龙袍的中年男子，站在一条人工河旁，45度角俯视地面，思考着种种问题。
“叮！您已加入位面群。公告已发放。”
突然，一个声音出现在他耳旁。
“嗯？这是？”
男子沉默了一会。
“我！amp&&&&。”（被禁字符）
“天助我也，真是天助我也！”
（古代皇帝不会自称‘朕’，不要被电视剧骗了。）
“哈哈哈哈哈！！！”
男子发狂似的大笑了好半天。
“陛下，陛下您怎么了！”
笑得身旁的几个宦官都头皮发麻。
“我没事！我很好！”
中年男子大手一挥。
“起驾，回宫！”
“是，皇上。”
一行人浩浩荡荡的离开了此地。
回到寝宫后。朱棣回味着脑中的《明朝那些事儿》
“妙，真是妙啊！”
“不愧是仙人手段！”
朱棣拿起砚台上的毛笔，龙飞凤舞的画出了一个图纸。
一个很简单的金属管子，后面配上长长的木托。
朱棣转身，大步迈向门口。
“快，吩咐下去。让铁匠做一个一摸一样的。”
“另外，拟圣旨。”
一个宦官拿着图纸小跑离开了，另一个宦官手忙脚乱的拿出笔和纸。
“宣，京城内所有炼制坊。务必与匠人一同面圣。”
“好了，都下去吧。尽快把事情办妥。”
朱棣转身关上门，继续拿起笔。
龙飞凤舞的字迹，一篇又一篇化学公式。
钢铁脱磷，硝化甘油，石油制品......
火绳枪，燧发枪，单发定装弹步枪，弹板定装弹步枪，水冷机枪......
蒸汽机，内燃机，直流电机，灯泡......
单引擎双翼机，单引擎单翼机，双引擎单翼机......
玉米，地瓜，土豆......
朱棣回味着脑中的《高中物理》《高中化学》《高中数学》《高中生物》
“唉，这天，要变了啊。”
时间过得飞快。
第二天早朝。
“禀皇上，京城内的匠人已全数在此。”
朱棣看着下方一群跪着不敢抬头的匠人们，大声开口道。
“今日，朕宣诸位，只为一事。”
然后就是不啦不啦，长篇大论。
五个小时后。
简单总结一下。
以后这群匠人就为皇宫服务了，但是需要为了皇宫而炼制特殊的铁。
保密协议是少不了的，而且后果是剁脑袋。
并且，据皇上所说。‘西洋’引进的测谎仪可以完美解决问题。
最后。
“这，就是我们目前的目标！一起都是为了它的铺垫！”
朱棣拿出一张长长的画轴，铺开在大殿之上。
画轴上写着。
First things first. Let’s have a look at what Einstein really did say about the relation between mass and energy.
Equivalence or transformation?
For Einstein， mass (more precisely: relativistic mass; the property that determines how difficult it is to change a body’s speed or its direction of motion) and energy are simply two different names for one and the same physical quantity. Whenever a system has an energy E， it automatically has the relativistic mass m=E/c2; whenever a system has the mass m， you need to assign it an energy E=mc2. Once the mass is known， so is the energy， and vice versa. In that context， it makes no sense to talk about the “transformation of mass into energy”– where there’s one， there’s the other.
The context in which “transformation of mass into energy” does make sense is a bit different. It is intimately connected with the fact that there are different kinds of energy. Already in classical， pre-Einstein physics， the concept of “energy” comprises a plethora of sub-definitions for different sorts of energy， sub-definitions like those for the kinetic energy associated with any moving body， the energy of electromagnetic radiation， thermal energy or the binding energy that needs to be taken into account whenever there is a force holding together two objects to form a composite object. Yet all these different definitions can be viewed as facets of a single physical quantity， energy. The reason is the possibility of transformations between the different energy forms. For instance， you can increase a body’s temperature (and thus its thermal energy) by letting it absorb electromagnetic radiation energy. In these transformations， the total sum of all the different kinds of energy – the total energy – is constant over time. Energy can be transformed from one variety into another， but it can neither vanish nor be created from nothing.
A new kind of energy
This conservation of energy holds not only in classical physics， but also in special relativity. However， in relativity， the definitions of the different species of energy are a bit different and， most importantly， there is a completely new type of energy: even if a particle is neither moving nor part of a bound system， it has an associated energy， simply because of its mass. This is called the particle’s rest energy， and it is related to the particle’s rest mass as
rest energy =(rest mass)· c2.
Compared with other types of energy， rest energy is very much concentrated. For example: If you use a television tube to accelerate an electron to 20，000 kilometres per second， the kinetic energy gained is still only about five hundred times smaller than the electron’s rest energy. Also， this rest energy is about a hundred times larger than the radiation energy of a high-energy X-ray photon. This high concentration is important for processes where rest energy (or， equivalently， rest mass) is converted to more common forms of energy. For instance， when a particle and its anti-particle annihilate and vanish in a puff of electromagnetic radiation， comparatively little matter is transformed into rather a lot radiation.
Studying the masses of different types of atomic nuclei， you will find that in nuclear fission – the process that powers an ordinary atomic bomb -， some “nuclear rest energy” or “nuclear rest mass” is transformed into other forms of energy. For example， the rest mass of a nucleus of uranium-235 is slightly larger than the combined rest masses of the nuclear fragments into which it splits during nuclear fission. Here’s where E=mc2 comes into play: This mass difference corresponds to the energy set free during nuclear fission. So is it， after all， true that Einstein’s formula explains the power of the nuclear bomb – and that the large conversion factor c2 is responsible for the immense amounts of energy released?
Binding energies: nuclei vs. molecules
Not at all. Different process， same calculation: For chemical reactions， there are tiny mass differences as well. To pick an example: When hydrogen and oxygen explosively combine to make water， the sum of the rest masses of the initial hydrogen and oxygen atoms is just a little bit less than the sum of the rest masses of the resulting water molecules. The same is true for the chemical reactions involving spontaneous oxydation – in other words: burning. The same formula applies: The mass difference， multiplied by c2， gives the energy set free during the chemical reaction. Same formula， same conversion factor – yet chemical reactions are much less violent than nuclear explosions. This clearly shows that the difference between nuclear and chemical reactions must be due to something other than E=mc2.
To see where the difference lies， one must take a closer look. Atomic nuclei aren’t elementary and indivisible. They have component parts， namely protons and neutrons. In order to understand nuclear fission (or fusion)， it is necessary to examine the bonds between these components. First of all， there are the nuclear forces binding protons and neutrons together. Then， there are further forces， for instance the electric force with which all the protons repel each other due to the fact they all carry the same electric charge. Associated with all of these forces are what is called binding energies – the energies you need to supply to pry apart an assemblage of protons and neutrons， or to overcome the electric repulsion between two protons.(More information about these binding energies and their role in nuclear fission and fusion can be found in the spotlight topic Is the whole the sum of its parts?)
Only with the systematics of these forces and binding energies well understood were physicists able to uncover the laws behind nuclear fission and fusion: The strength of the nuclear bond depends on the number of neutrons and protons involved. It varies in such a way that binding energy is released both in splitting up a heavy nucleus into smaller parts and in fusing light nuclei into heavier ones. This， as well as the chain reaction phenomenon， explains the immense power of nuclear bombs.
Einstein’s formula plays second fiddle in that derivation – it’s all about different kinds of energy. Sure， there are some radioactive decay processes following nuclear fission， and， if so inclined， one can view the decay of a neutron decaying into a slightly lighter proton as a transformation of rest energy into other energy forms. But these additional processes contribute a mere 10 per cent of the total energy set free in nuclear fission. The main contribution is due to binding energy being converted to other forms of energy – a consequence not of Einstein’s formula， but of the fact that nuclear forces are comparatively strong， and that certain lighter nuclei are much more strongly bound than certain more massive nuclei.
Still， E=mc2 had a supporting role in the story of nuclear fission research. Not as the mechanism behind nuclear power， but as a tool: Because energy and mass are equivalent， highly sensitive measurements of the masses of different atomic nuclei gave the researchers important clues about the strength of the nuclear bond. Einstein’s formula does not tell us why the nuclear binding energies are as large as they are， but it opens up one way (among several) to measure these binding energies.(More about this application of Einstein’s formula can be found in the spotlight topic Is the whole the sum of its parts?)
In fact， Einstein’s politics played a more decisive role in the story of the atomic bomb than his physics. Following a request by the physicist Leo Szilard， Einstein wrote a letter to president Roosevelt， explaining about the potential power of nuclear weapons and the possibility of Nazi Germany developing such weapons， and urging the president to take action. Einstein’s letter played its part in setting into motion the political process that culminated in the Manhattan project – the development， construction and testing of the first nuclear bombs.
（以上，为核弹公式以及来源的详细解释。反正是免费章节，给大家补补知识。）
朝堂内的人全都一脸懵。
这是啥子？
“先把眼前的事情做好！其他的以后再说。”
“下朝。”
朱棣转身离开。
