Argument50 彗星撞地球-我的第一篇完整argu，求拍！

smilinglUID: 2684200

50From a draft textbook manuscript submitted to a publisher.

"As Earth was being formed out of the collision of space rocks, the heat from those collisions and from the increasing gravitational energy of the planet made the entire planet molten, even the surface. Any water present would have evaporated and gone off into space. As the planet approached its current size, however, its gravitation became strong enough to hold gases and water vapor around it as an atmosphere. Because comets are largely ice made up of frozen water and gases, a comet striking Earth then would have vaporized. The resulting water vapor would have been retained in the atmosphere, eventually falling as rain on the cooled and solidified surface of Earth. Therefore, the water in Earth's oceans must have originated from comets."



This article concludes that the water in the oceans originated from comets which stroke the Earth. To justify this conclusion the article's author notes that comets are made up of frozen water and gases, which may vaporize when striking the Earth and the water or water vapor would retain in the oceans or atmosphere. The author also cites a conclusion that the temperature of the entire planet was once too high to hold water. Thus any water on the surface would vaporize and went off into space. In addition, the author also claims that the Earth's gravitation was not strong enough to hold water vapor and gases as its atmosphere until recent ages, so the water in the Earth now could have come from space. While I find the argument unpersuasive for several reasons.

First I think that the author makes a vicious circle. On one hand, the author points out that the Earth could hardly hold any water and gases until its gravitation became strong enough. On the other hand, the author also points out that the comets are made up of water and gases, which may vaporize when stroke the Earth because of the high temperature of the surface. Thus the comets hit the Earth would not add any mass for the Earth which is formed out of the collision of the space rocks, according to the point the author cites. Therefore it is not until the gravitation of the Earth grew strong enough when the water of comets could retain around the Earth. Before the mass of Earth grew to the point when it could force the atmosphere around it, whatever how many comets stroke to the Earth would only vaporize and go off into space. Therefore, the demonstration of the author may just prove that the water of the Earth would come from other forms.

Second, the author fails to consider about the quantity of water in the Earth. As if all the water comes from the comets which stroke the Earth, it can be calculated that how many of the comets in which common size would provide the quantity of water mentioned above. Perhaps the number of the comets needed is quite large that there has never been so many comets met the Earth from the beginning of the universe.

Third, even if the total mass of the comets stroke the Earth is proved to be larger enough than the quantity of water in the Earth, the author unfairly assumes that all of the water came from the comets. Apart from the striking of the comets, there should be other methods to form water, which the author does not mention. It may be quite possible that the water was formed by chemical affects on the Earth itself during the growing to current size. Thus ,lacking evidence that there has not been the chemical affects, the argument's claim that all the water of Earth originated from comets is dubious.

In sum, the recommendation for the water of Earth coming from the comets is not well supported. To better evaluate the recommendation, the author must provide clear statistical evidence that the Earth, during its low gravitation time, can hold the water vapor provided by the comets stroke it and, there's no other way for the Earth to produce any water.

victorylkUID: 2771912

牛啊，打字速度真够快的，我第一篇issue看着别人的中文提纲，才写了300字就到时间了~

罪果UID: 2792414

这篇貌似很难啊~我不敢写~

yingblankUID: 2708028

我刚才写了这篇，写了一点实在是觉得写不下去了，因此放弃了。我现在基本是等死了。
楼主真的好强大啊。

smilinglUID: 2684200

大家别误会，我不可能在半小时打这么多字，没掐时间写的——真让我说用了多少时间恐怕得说是两天吧orz
有没有也写过这篇的同学指导下，第二段那种写法行吗？我觉得已经不止是在写argu了……可是这篇如果抛开专业背景怎么能找得到足够的漏洞啊？无限纠结中……