0910AW 同主题写作第十五期 ARGUMENT 50 by swif

swifUID: 2530426

题目主帖：https://bbs.gter.net/thread-990391-1-1.html

50.From 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."

In this argument, the author claims that the water in Earth's oceans must have originated from comets. To sustain this claim, the author points out that the heat from those collisions which breed Earth and  gravitational energy of the planet made the water of Earth all evaporated and gone off  into space, and after the earth's gravitation became strong enough water vapor from comets' collisions with earth would have been retained in the atmosphere which eventually falling as rain on the surface of Earth. I find the argument unpersuasive for several reasons.

  Firstly, the argument mentioned that any water present would have evaporated and gone off into space. But no evidence can substantiate that even a water molecule could not remain in the inside of the earth. Although most of the water of Earth had evaporated and gone off into space, it's not confirmed that 100 percent of the water had. It's possible that a little bit of water still remain inside Earth or in the space surrounding Earth and these water could also be a part of the water in Earth's oceans . It's unconvincing to say that the water in Earth's oceans must have originated from comets.

  Secondly, the author cites the fact that a comet striking Earth would bring water to Earth. But what about no one comet has stroke Earth since the its gravitation became strong enough to hold gasses and water vapor around it. The author provided no materials to tell us that there is any comet striking Earth then. If no comet striking Earth, how can we believe that the water in Earth's oceans must oriented from comets?

  Thirdly, the author's words contradict each other which made it rather suspicious. At start, the author says that collisions of space rocks created much heat which made the entire Earth molten along with the gravitational energy and then made the water gone off into space. So later comets' collision could also drive the water into space in the same way. But the author's wording later is to the opposite side: water would remain on earth and form the oceans. This strange logic quite unbelievable.

  Finally, the argument is assertive because it does not take some other origins of water into account. One important origin of water is chemical reaction. As we know, numerous kinds of reactions can produce water ,thus the quantity of water produced by chemical reaction can be considerable. The author does not provide any evidence to ruling out such possibilities.

  In sum, the allegation that the water in oceans must have originated from the comets is unconvincing. To be more persuasive, the author should provide more evidence such the record of comets' collision with Earth,and consider some other origin of water.

swifUID: 2530426

没人改啊   自己顶一下

AdelineShenUID: 2630498

贴一下我的提纲吧~

1.        Earth being formed out of the collision of space rocks is only one of the various versions of hypothesis about the formation of Earth none of which has been substantiated yet. The conclusion deduced from such a hypothesis is open to controversy.（背景？可以驳吗？）
2.        前提是在地球在达到目前体积，重力足够留住气体和水蒸汽后，有彗星撞击过地球。论者没有提供任何这方面的证据。如果这之后没有撞击发生，海水就不可能来源于彗星。
3.        即使那以后有彗星撞击过地球，可能彗星撞击后水蒸气速度太大，地球的引力根本抓不住他。There is no evidence indicating that the water in comets can successfully reach the surface of the earth. It is possible that the comets evaporates at very exterior of atmosphere and gravitaion is so weak there that the vapor escape in to the space.
4.        即使有彗星撞击给地球带来一些水，并不能说明地球海洋的水就是源自彗星，还有其他很多可能，可能水更多的是来自元素之间的化学反应，还有可能是其他的星体撞击给地球带来的水等等。