Q13

[rmoncel]

Hi,

The question asks which additional piece of information would support the view that the LHB was limited to Earth and the Moon.

I think A and D both do the job. I can't figure out why D wouldn't work. The rock from Mars is held by the author in the 3rd para as key preliminary evidence that LHB extended beyond the Earth-Moon system. If the rock actually originated on the Moon rather than Mars (as answer D posits), wouldn't that discredit the view that HLB extended beyond the Earth-Moon system?

Thanks for your help!

[mrudula_2005]

Can you help me understand why A is better than D? Doesn't D lend good support to the view that the LHB was limited to just the Earth and the Moon by discounting the only evidence that shows that the LHB extended throughout the inner solar system (the last paragraph's talk of the Mars rock)?


thanks!

[ManhattanPrepLSAT2]

Oh boy is this a challenging question! Thanks for bringing it to the board.

(D) is indeed a very tempting answer. If (D) is true, we take away evidence from an alternative view. But does weakening an alternative view strengthen the view that the LHB was limited to Earth and Moon? Not necessarily -- this isn't an absolute, one-of-two-possibilities sort of situation.

Does (D) provide more direct support, then, for the idea that the LHB was limited to the Earth and the Moon? Seems to, but it does not match up well with what we've been told in the text. In the text, we're told that according to this theory debris from the disintegration of another body stayed within the Earth-Moon system -- it's unclear how elements from the moon being found on the earth helps or supports this idea.

Again, a super tempting answer -- one of the most tempting I've ever seen on RC! Hopefully this helps, but please let us know if you have any follow-ups.

[bbirdwell]

The Mars rock is not the only piece of evidence that supports that view. The first third of the second paragraph supports that view. The Mars rock is merely "new support" for that idea.

The issue here is Inner Solar System vs Earth-Moon-only. B, C, and D all have to with one or a few rocks. Big deal! Can we account for every single rock out there? Exceptions-to-the-rule have very little impact on logical arguments, generally.

(A) rules out Mars entirely -- no projectile damage on the planet at all ("very little evidence"). Mars, from the contextual evidence in the passage, is part of the Inner Solar System. Ruling it out entirely from the bombardment is a point for the Earth-Moon-only camp.

[jiyoonsim]

Took a while for me to figure out even with the explanations, but in the end I figured it out (I think)

Here's a bit of sum on the passage, especially the parts we have to know to tackle this question.

Viewpoint 1: asteroids/comets around sun affected planets in inner solar system.
- Martian rock is found on Earth.

Viewpoint 2: Long period of bombing
- Early proofs of projectile are gone due to heavy later bombardment

Viewpoint 3: Between Moon and Earth only
- Each other's body debris gone quickly


Though confusing, in the end I think this question is all about strengthening the Viewpoint 3. In other words, we really have to limit the scope to between Moon and Earth only and make it airtight.

A) does that by canceling out the possible "3rd factor" - it rules out Mars, the other planet away from Moon and Earth.

B), C), D), E) all have a hole that makes it possible to have debris/rocks from Mars (or any third planet away from Moon and Earth).

[zainrizvi]

The Mars rock is not the only piece of evidence that supports that view. The first third of the second paragraph supports that view. The Mars rock is merely "new support" for that idea.

The issue here is Inner Solar System vs Earth-Moon-only. B, C, and D all have to with one or a few rocks. Big deal! Can we account for every single rock out there? Exceptions-to-the-rule have very little impact on logical arguments, generally.

(A) rules out Mars entirely -- no projectile damage on the planet at all ("very little evidence"). Mars, from the contextual evidence in the passage, is part of the Inner Solar System. Ruling it out entirely from the bombardment is a point for the Earth-Moon-only camp.

Isn't this exactly what Mike was saying to avoid though?

If (D) is true, we take away evidence from an alternative view. But does weakening an alternative view strengthen the view that the LHB was limited to Earth and Moon? Not necessarily -- this isn't an absolute, one-of-two-possibilities sort of situation.

[bragg.tim]

(D) is indeed a very tempting answer. If (D) is true, we take away evidence from an alternative view. But does weakening an alternative view strengthen the view that the LHB was limited to Earth and Moon? Not necessarily -- this isn't an absolute, one-of-two-possibilities sort of situation.

Can we assume that in strengthen questions that answer choices that simply weaken an opposing view are tricks, and thus eliminate them? Or, is this just an area where we need to take caution, knowing that it could be a trick answer?

[shodges]

(D) is indeed a very tempting answer. If (D) is true, we take away evidence from an alternative view. But does weakening an alternative view strengthen the view that the LHB was limited to Earth and Moon? Not necessarily -- this isn't an absolute, one-of-two-possibilities sort of situation.

Can we assume that in strengthen questions that answer choices that simply weaken an opposing view are tricks, and thus eliminate them? Or, is this just an area where we need to take caution, knowing that it could be a trick answer?

I've got this question as well. I can see this being a blanket concept, that weakening one position does not necessarily strengthen another. However, I could also see weakening one theory as being able to strengthen the "probability" of another by discrediting the other.

[kimht90]

Okay so I'm trying to fully understand how answer choice (D) is incorrect. My initial attempt to discredit answer choice (D) was that (A) was DIRECTLY pertinent to the bombardment when (D) did NOT mention LHB at all. It merely focused on the origin on the rock. (one single rock, which isn't very helpful when it comes to strengthening or weakening questions anyway) So, If I were to say that the rock believed to have originated on Mars actually originated on the Moon AS A RESULT OF LHB, (I think when I chose this answer choice, I was picturing a piece of rock flying all the way from Mars and landing on the Moon as a consequence of a lousy, big explosion in my head) I would be making an unwarranted assumption myself, right? I think that is how I fell into this super attractive answer choice. Can any one of the instructors help reaffirm my newfound convinction? Thank you so much!!

[oscey12]

So "very little evidence" = "no evidence?" And a lack of evidence (although the survey is extensive) means that the inner solar system theory is false? Appreciate any help on this one...

[ffamran.ps]

When I tried this question, I ruled out (A); could someone show me where I went wrong?

So (A) says that there is little evidence for an increase in intensity; therefore, there may be evidence for a decrease in intensity. I thought this meant that (A) did not have any effect on the second LHB theory (theory 2), presented in lines 21-31, which considers projectiles of declining intensity.

The passage did say that theory 2 believes that the final impacts on the moon destroyed evidence of all other impacts, but since the sentence before says the intensity was declining, I reasoned that theory 2 believes the earlier impacts were so intense that even a relatively weaker impact at the end was evidence-destroying. I also reasoned that, since the Moon is smaller than Mars, an impact that destroyed all evidence on the Moon would not necessarily have had the same effect on Mars.

[barry036]

I have this question too. Isn't (A) compatible with the theory of "continuous, declining heavy bombardment throughout the inner solar system"?

This question has motivated my first post here. I see that (D) isn't very strong, but what am I missing about (A) and the second theory?

[DavidS899]

For the life of me I can't comprehend this at all.

(A) says
"An extensive survey of craters on Mars shows very little evidence for an increase in the intensity of projectiles striking Mars during the period from three billion to five billion years ago."

Ok LSAT people does little evidence of an increase in a set period necessarily mean there was not consistent heavy bombardment throughout this entire period? We know the LHB has to occur approximately 4 billion years ago, well what if in fact the heavy bombardment occurred at an unchanged or decreasing rate from three to five billion years ago but impacted the whole solar system not just the Earth and the Moon? Wouldn't that still allow (A) to be accepted and reject the view that it was limited to the Earth and the Moon? This theory would also reject the idea that it was of "relatively short duration" as is suggested in the third view.

The third view is weakened by the argument that follows it in the third paragraph. And the evidence to support this conclusion which is at odds with our third view is the rock. They even drop a bunch of hints for the importance of this single rock like "seems to be a rare example", "tiny piece of evidence", "to determine pervasiveness... will need to locate many more such rocks".

It seems to me if "further testing" disproved the Mars origin of this rock that almost all the evidence presented for the view refuting our third view would be undermined.

Am I from a hunk of rock knocked off of Mars or...?

[JovyT883]

For the life of me I can't comprehend this at all.

(A) says
"An extensive survey of craters on Mars shows very little evidence for an increase in the intensity of projectiles striking Mars during the period from three billion to five billion years ago."

Ok LSAT people does little evidence of an increase in a set period necessarily mean there was not consistent heavy bombardment throughout this entire period? We know the LHB has to occur approximately 4 billion years ago, well what if in fact the heavy bombardment occurred at an unchanged or decreasing rate from three to five billion years ago but impacted the whole solar system not just the Earth and the Moon? Wouldn't that still allow (A) to be accepted and reject the view that it was limited to the Earth and the Moon? This theory would also reject the idea that it was of "relatively short duration" as is suggested in the third view.

Same here, I have completely no idea which part of the passage "an increase in the intensity of projectiles" is trying to attack.....

[Yu440]

For the life of me I can't comprehend this at all.

(A) says
"An extensive survey of craters on Mars shows very little evidence for an increase in the intensity of projectiles striking Mars during the period from three billion to five billion years ago."

Ok LSAT people does little evidence of an increase in a set period necessarily mean there was not consistent heavy bombardment throughout this entire period? We know the LHB has to occur approximately 4 billion years ago, well what if in fact the heavy bombardment occurred at an unchanged or decreasing rate from three to five billion years ago but impacted the whole solar system not just the Earth and the Moon? Wouldn't that still allow (A) to be accepted and reject the view that it was limited to the Earth and the Moon? This theory would also reject the idea that it was of "relatively short duration" as is suggested in the third view.

Same here, I have completely no idea which part of the passage "an increase in the intensity of projectiles" is trying to attack.....

Me too.... I eliminated A based on the fact it said "increase in the intensity of projectiles". I thought even if there wasn't an increase, the LHB could still be knocking Mars right? Unless we're assuming that there wasn't any other heavy bombardments before 4 billion years ago?

[Yu440]

Wait, I think I understand it now. Since LHB only occurred 4 billion years ago, as long as it struck Mars we can count it towards an increase in the intensity?

[ohthatpatrick]

The question stem asks us to pick an answer that makes it seem more likely (not proof) that only the Earth and the Moon experienced the LHB - "a vigorous bombardment of debris approximately four billion years ago".

From the context of the passage's discussion, we've got a few theories:

THEORY 1:
an object got destroyed by coming too close to the sun and peppered the inner solar system (Mercury, Venus, Earth, Mars) with debris.

THEORY 2:
the whole inner solar was peppered with debris, but there wasn't some special uptick around 4 billion years ago

THEORY 3:
an object got destroyed in the neighborhood of the Earth/Moon, and so only those two bodies were significantly hit with debris.

So we could paraphrase our task here as "which of these answers makes Theory 3 sound more like the correct one"?

(A) This says that it looks like Mars was NOT hit by a vigorous bombardment of debris 4 billion years ago, i.e. Mars was not involved in the LHB.

Does "very little evidence" mean "no evidence"?
Of course not, but we're just strengthening, not proving.

Does learning that "MARS was not hit by the LHB" tell us that "the LHB was limited to the Earth/Moon"?
Of course not ... maybe Mercury and Venus were hit, even though Mars wasn't. However, from the context of the passage, it was either a theory that the entire inner solar system was impacted (literally) or that it was limited to Earth/Moon. So if Mars isn't being hit, we would think "okay, I guess there wasn't debris throughout the whole inner solar system", which pushes us closer to the idea that it was limited to the Earth/Moon system.

Could Mars have still been getting hit by projectiles from 3 - 5 billion years ago?
Sure, but the "L" and "H" in LHB stand for Late, Heavy Bombardment.

Mars, and all the planets, are forever going to be bombarded with projectiles to an extent. But the LHB is a hypothetical idea that there was a relatively brief and extra-intense surge of debris around the 4 billion year mark.

So if you looked at the debris hitting Mars from 3 - 5 billion years ago and didn't see any uptick around the 4 billion year mark, then you would know that "the LHB, if it happened, didn't affect Mars"

Hope this helps.