argument50 传说中的难题，流连必回

ILOVEISSUEUID: 2300195

TOPIC: ARGUMENT50 - 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."
WORDS: 458          TIME: 0:30:00          DATE: 2007-3-16

In this article, the author concludes that the water in Earth's oceans must have originated from comets. Yet, close scrutiny on the evidence provided by the author reveals that it lends little credible support to this conclusion.

In the first place, the author relies on the presumptuous assumption that there were enough comets that have struck the earth. Although there the earth is formed of the collision of space rocks, the author misleads us to think that those space rocks also included comets. Yet the author fails to prove that it is the case. In fact, since comets are largely ice made up of frozen water, it is entirely possible that in the motion of comets, most of the comets had already molten due to the heat caused by friction.  Under such circumstance, the author's assumption will be open to question.

In the second place, even if some comets had struck the earth, author unfairly assumes that the resulting water vapor would have been retained in the atmosphere. Yet it is probably not the case. As the author implies that in order to retain water vapor, the earth must approach its current size. However, it is entirely possible that at that time the body of earth was not big enough thus being unable to hold gases and water vapor around it. In addition, the author fails to consider the affection of other planets. For example, perhaps at the time when earth was being formed, there was a large planet beside it, which was so large that gravitate the gas around the earth.  In such cases, the author claims that water vapor would have been retained in the atmosphere is questionable.

In the second place, even if the resulting water vapor was retained, the author unfairly assumes that these water will fall as rain and become water. However, we can find no evidence in the argument to support this assumption. Common sense tells me that the precondition that water vapor will fall as rain is that the concentration of vapor in the atmosphere is high enough and above the saturated vapor pressure. Nevertheless, it is possible that at that time the concentration of water is not high enough due to the huge volume of atmosphere. If so, then the water may no fall as rain.  In addition, since the surface temperature of earth is quite high, it is possible that the water might decompose or react with some objects to other ones. In such cases, the author's assumption that water vapor will fall as rain on the earth is open to doubt.  

Finally, even if the foregoing assumptions are all substantiated, the author's conclusion that the water in Earth's oceans must have originated from comets is still unwarranted. The author fails to take into account other possible alternatives that cause water. Such alternatives may include the fact that the certain chemical reaction between some elements will also give water. For example, hydrogen and oxygen, two elements that is common in the universe, can be combined to water in a high temperature or in the existence of some metal. If so, then some water in the ocean may have nothing to do with the comets but the result of some chemical reaction. Without ruling out this alternative explanation, the author cannot justifiably conclude that the water must originated from comets.

In sum, this argument fails to convince me. To substantiate it, the author should provide sufficient evidence to support that the temperature of planet was high enough for the water to vaporize. The author also should provide evidence to preclude the other possible origin of water. To better evaluate this argument, I should also need to know whether there are enough comets that had struck earth.

daphneliUID: 2247309

In this article, the author concludes that the water in Earth's oceans must have originated from comets. Yet, close scrutiny on the evidence provided by the author reveals that it lends little credible support to this conclusion.

In the first place, the author relies on the presumptuous assumption that there were enough comets that have struck the earth. Although there the earth is formed （out）of the collision of space rocks, the author misleads us to think that those space rocks also included comets.(有些牵强，如果想以此支持TS，还需要多说几句) Yet the author fails to prove that it is the case. In fact, since comets are largely ice made up of frozen water, it is entirely possible that in the motion of comets, most of the comets had already molten due to the heat caused by friction.  Under such circumstance, the author's assumption will be open to question.

In the second place, even if some(enough) comets had struck the earth, author unfairly assumes that the resulting water vapor would have been retained in the atmosphere. Yet it is probably not the case. As the author implies that in order to retain water vapor, the earth must approach its current size. However, it is entirely possible that at that time the body of earth was not big enough（the gravitation of the earth was not strong enough） thus being unable(建议去掉) to hold gases and water vapor around it. In addition, the author fails to consider the affection of other planets. For example, perhaps at the time when earth was being formed, there was a large planet beside it, which was so large that gravitate the gas around the earth. (不知道这个可能性是否存在， 地球周围的行星距离地球非常远，能吸引气体吗) In such cases, the author claims that water vapor would have been retained in the atmosphere is questionable.

In the second place, even if the resulting water vapor was retained, the author unfairly assumes that these water will fall as rain and become water. However（可以去掉）, we can find no evidence in the argument to support this assumption. Common sense tells me that the precondition that water vapor will fall as rain is that the concentration of vapor in the atmosphere is high enough and above the saturated vapor pressure. Nevertheless, it is possible that at that time the concentration of water（vapor） is(was) not high enough due to the huge volume of atmosphere（现在huge volume of atmosphere也存在， 但是水蒸汽还是可以以雨的形式降落）. If so, then the water may no fall as rain.  In addition, since the surface temperature of earth is quite high, it is possible that the water might decompose or react with some objects to other ones. In such cases, the author's assumption that water vapor will fall as rain on the earth is open to doubt.  

Finally, even if the foregoing assumptions are all substantiated, the author's conclusion that the water in Earth's oceans must have originated from comets is still unwarranted. The author fails to take into account other possible alternatives that cause water. Such alternatives may include the fact that the certain chemical reaction between some elements will (may)also give water. For example, hydrogen and oxygen, two elements that is common in the universe, can be combined to water in a high temperature or in the existence of some metal. If so, then some water in the ocean may have nothing to do with the comets but the result of some chemical reaction. Without ruling out this alternative explanation(other alternative explanations), the author cannot justifiably conclude that the water must (have)originated from comets.

In sum, this argument fails to convince me. To substantiate it, the author should provide sufficient evidence to support that the temperature of planet was high enough for the water to vaporize. The author also should provide evidence to preclude the other possible origin of water. To better evaluate this argument, I should also need to know whether there are enough comets that had struck earth.

只是我的看法呵呵，有时间可以去看看我的
http://bbs.gter.ce.cn/bbs/thread-634040-1-1.html

[ 本帖最后由 daphneli 于 2007-3-24 01:03 编辑 ]

ILOVEISSUEUID: 2300195

这个是我参考别人的攻击点写得

cocoon_mmUID: 2259908

the author misleads us to think that those space rocks also included comets
这个第一点有点牵强吧

ILOVEISSUEUID: 2300195

up