While space looks empty, it is in fact filled with matter. In 1933, Sw

Question

While space looks empty, it is in fact filled with matter. In 1933, Swiss astrophysicist Fritz Zwicky coined the term “dark matter” to identify the substance that makes up an estimated 85% of all matter in the universe. Ever since, however, the search for the particles that compose dark matter has been ongoing with hypotheses and projections filling the minds of determined physicists in search of a breakthrough.

Among the most promising hypotheses is one that includes neutralinos, a proposed particle akin to the Higgs Boson particle as a building block of the universe we know. Neutralinos, it is proposed, will annihilate each other when they collide, producing both a matter and an antimatter equivalent (an electron and a positron, respectively). In such a reaction, each particle would carry with it as much energy as one neutralino has mass (per Einstein’s theory of relativity), and this energy may well provide the means for which scientists can finally identify these sought-after particles.

The plausibility of this theory has galvanized support in the scientific community for extensive research. Aboard the International Space Station lies the Alpha Magnetic Spectrometer (AMS), which is using magnetized sensors to identify the charges that would come along with these proposed particles. As it measures charges across space, AMS focuses on the variance of the ratio of positrons to electrons, under the theory that the “positron fraction” should peak when these high-energy positrons are created from dark-matter annihilation. To date, AMS has recorded over 30 billion cosmic rays and research indicates that it has indeed viewed hundreds of thousands of charged particles consistent with the theory of positrons. But scientists remain stoic on the issue, noting that these charges are potentially also consistent with those released by pulsars, the aftermath of exploded stars. Accordingly, research continues to better delineate between the positron fraction expected from pulsars and that from neutralinos.   1 
 D 
 1. Which of the following best summarizes the primary purpose of the passage?

A. To compare the search for neutralinos with that for the Higgs Boson
B. To detail the current hypotheses regarding the origin of dark matter
C. To prove that positrons are created from dark matter annihilation
D. To present a hypothesis to explain a mysterious scientific phenomenon
E. To explain the results of a current scientific research study

2 
 B 
 2. Which of the following can be inferred from the passage?

A. The highest positron fractions that AMS records will be from dark matter particles.
B. Electrons and positrons carry approximately the same amount of energy.
C. AMS has been able to view hundreds of thousands of positrons.
D. The charges emitted by pulsars are indistinguishable from the charges emitted by positrons.
E. The neutralino hypothesis is currently accepted as the most plausible existing explanation for dark matter.

3  
 D 
 3. According to the passage, scientists theorize that dark matter is created when

A. The positron fraction reaches its peak value
B. Pulsars result as the remnants of stellar explosion
C. Positrons release the same amount of energy as a neutralino has mass
D. Neutralinos collide with one another
E. Highly charged electrons annihilate positrons

CrackverbalGMAT · Answer

Map the passage so that it becomes easier to answer the questions -

Para 1 - gives context about dark matter; says there are various hypotheses
Para 2 - talks about 1 such hypothesis - Neutralino hypothesis
Para 3 - Interest in the hypothesis-> AMS -> results not conclusive

You have to read the first 2 sentences and last sentence of each paragraph carefully to get a grasp of the main idea.
Clearly, from the map we can see that the passage has something to do with the neutralino hypothesis.

Q1.
A - Higgs boson is mentioned in only one sentence in the 2nd paragraph. Incorrect.
B - note the word "hypotheses". The passage talks only about one hypothesis.
C - No mention of the neutralino hypothesis. Note the word "prove" - no where does the author go to prove anything. The author does not give his opinion on the hypothesis. All he/she does is to detail it. Also, this option seems to suggest that positrons are only created by dark matter annihilation. We know that they are emitted from pulsars too. 
Another red flag is that the option does mention electrons at all. 
D - correct answer.
E - Nowhere does the author explain the results of the study. He/she just says that scientists are stoic on the issue. Another thing - this option is talked about only in the penultimate sentence of the passage.

Q2.

A - When you see the word "AMS" immediately go the 3rd paragraph and read it. the paragraph says - "positron fraction should peak when there is dark matter annihilation." Nowhere does it say positron fraction should be the highest from dark matter annihilation. Note the extreme word  "highest" . The passage does not talk, for example, as to how positron fractions from pulsars compare to those from dark matter annihilation. 
B - "Electrons and positrons" - go the 2nd paragraph. DO NOT bring in outside knowledge. The paragraph clearly states " in such a reaction , electrons and positrons carry approximately the same amount of energy". Incorrect.
C - correct answer. 3rd paragraph - "research indeed indicates ..."
D - "pulsars" - go to the 3rd paragraph. "research continues to better delineate ...". Incorrect
E - Only the author says "most promising theory". We DO NOT know the view point of others. Again, "the plausibility of this theory has galvanized ..." does not mean that it is the MOST plausible theory.

Q3.
We need something that talks about neutralinos. Only option D does that.

KS15 · Answer

Could you please provide explanation for Qs 2-I marked A.

Thanks

abhimahna · Answer

Are we sure OA answer marked for 2nd question correct?

keats · Answer

I have cross checked and the OA to Q2 is B. Below is the OE for the same.

Solution: B.

This inference question comes with a high burden of proof – the correct answer must be true. Several answer choices are likely but not proven – A, for example, may well be true but the passage only states that the positron fraction of these particular charges peaks when positrons are created – this doesn’t mean that there aren’t higher positron fractions measurable from other reactions or phenomena. Choice C is also close but not absolute – the third paragraph states that AMS has viewed hundreds of thousands of instances “consistent with” the theory of positrons but falls short of guaranteeing that they were, in fact, positrons. Choice D is too strong – AMS has struggled with the fact that positron and pulsar charges are similar, but we do not know that they are in fact indistinguishable. And choice E is also not certain – the passage says that this theory is “among the most promising theories,” but that leaves room for other promising theories to be regarded as even more plausible.

abhimahna · Answer

I understand all the information you gave, but could you please help me understand how can we infer B. I have the solid reason for rejecting all choices but B. Still, I am not convinced with selecting B as a right answer choice. Could you share your views here?

keats · Answer

Sure  abhimahna

Let me give it a try. Lets quickly get to Para 2nd of the passage.

Among the most promising hypotheses is one that includes neutralinos, a proposed particle akin to the Higgs Boson particle as a building block of the universe we know.  Neutralinos, it is proposed, will annihilate each other when they collide, producing both a matter and an antimatter equivalent (an electron and a positron, respectively). In such a reaction, each particle would carry with it as much energy as one neutralino has mass (per Einstein’s theory of relativity), and this energy may well provide the means for which scientists can finally identify these sought-after particles .

From the italicized part, it is clear that the *neutralinos* destroy when they collide with each other and , as a result, produce both a matter and an antimatter equivalent. The antimatter equivalent comprises of a) an electron and b) a positron. Further, the text says that each particle will carry with it as much energy as one neutralino has mass. This means that both the electron and the positron will have energy equivalent to mass of 1 neutralino. This just strengthens the fact that they both carry same amount of energy.

This is the best I could do. I'm not really good at explaining. Still, let me know if you want me to elaborate further.

abhimahna · Answer

I truly appreciate your efforts friend. I just missed the line "each particle would carry with it as much energy as one neutralino has mass ". Thanks a lot friend.

goforgmat · Answer

The same line also says "in such a reaction" so it cannot be generalised to say that Electrons and neutrons both carry same amount of energy. B is incorrect answer choice in my opinion.
The 1st line in the 3rd paragraph says the plausibility has garnered support for extensive research meaning it is perhaps accepted as the most plausible hypothesis.
so E looks like a better choice.

dabaobao · Answer

Passage Map: 
1) Dark matter and its search
2) One hypothesis
3) Support for that hypothesis

richirish · Answer

Q2. is a classic BS answer, there is no solid ground to select B

thecardinal · Answer

I dont get how question 3 is D can someone help? Anti-matter is not dark matter.. Neutralinos from the passage are the elementary particle that builds dark matter. So we would need something that creates neutralinos. right?

Sajjad1994 · Answer

Explanation

3. According to the passage, scientists theorize that dark matter is created when

Explanation

The passage discusses the hypothesis that neutralinos, a proposed particle similar to the Higgs Boson particle, are a potential building block of dark matter. It suggests that when neutralinos collide, they will annihilate each other, producing both a matter and an antimatter equivalent (an electron and a positron, respectively). In this reaction, each particle would carry with it as much energy as one neutralino has mass, according to Einstein’s theory of relativity. Therefore, the creation of dark matter is associated with the collision and annihilation of neutralinos.   (D)   is correct.

A.  The positron fraction reaching its peak value is associated with the detection of high-energy positrons, which is a method used to search for evidence of dark matter annihilation, as mentioned in the passage. However, it does not directly relate to the creation of dark matter itself.

B.  Pulsars are discussed in the passage as potential sources of charged particles, but they are not directly related to the creation of dark matter. Pulsars are remnants of supernova explosions and are mentioned as a source of charged particles that could be mistaken for those resulting from dark matter annihilation.

C.  While positrons are mentioned in the context of dark matter annihilation,  (C)  does not accurately represent the process described in the passage. The passage states that neutralinos collide and annihilate each other, releasing energy equivalent to the mass of one neutralino, not that positrons release energy equal to neutralino mass.

E.  is incorrect because it describes a process involving electrons and positrons, but it does not relate to the creation of dark matter. The passage discusses the annihilation of neutralinos, not electrons and positrons.

Answer: D

VerbalBot · Answer

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While space looks empty, it is in fact filled with matter. In 1933, Sw

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While space looks empty, it is in fact filled with matter. In 1933, Sw

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