Reading ComprehensionDifficulty: Easy

PT121 S2 P3 Q14 Explanation

Neutrinos

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsMain PointScience

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Passage

According to the theory of gravitation, every particle of matter in the universe attracts every other particle with a force that increases as either the mass of the particles increases, or their proximity to one another increases, or both. Gravitation is believed to shape the structures of stars, galaxies, and the entire which they call “dark matter,” provides the gravitational force necessary to make the huge structures cohere.

What is dark matter? Numerous exotic entities have been postulated, but among the more attractive candidates—because they are known actually to exist—are neutrinos, elementary particles created as a by-product of nuclear fusion, radioactive decay, or catastrophic collisions between other particles. Neutrinos, which come in three types, are by far the most numerous matter cannot exert gravitational force; without such force, it cannot induce other matter to cohere.

But new evidence suggests that a neutrino does have mass. This evidence came by way of research findings supporting the existence of a long-theorized but never observed phenomenon called oscillation, whereby each of the three neutrino types can change into one of the others as it travels through space. Researchers held that were able to estimate the mass of a neutrino at from 0.5 to 5 electron volts.

While slight, even the lowest estimate would yield a lot of mass given that neutrinos are so numerous, especially considering that neutrinos were previously assumed to have no mass. Still, even at the highest estimate, neutrinos could only account for about 20 percent of the universe’s “missing” mass. Nevertheless, that is enough may add to our understanding of the role elementary particles play in holding the universe together.

What this question is testing

Main Point

Your task

Capture the passage's overall primary point — the claim everything else supports.

Common trap

Answers that are true but too narrow (a single paragraph) or too broad (beyond the passage's scope).

Winning move

Summarize the whole passage in one sentence first, then match it to a choice.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
14.

Which one of the following titles most completely and accurately expresses the contents

Answer choices

  1. Wrong Emphasis: lacks central topic2% picked this

    “The Existence of Dark Matter: Arguments For

    The central topic was neutrinos, not dark matter. Moreover, there was no argument against dark matter presented in the passage.

  2. Correct89% picked this

    “Neutrinos and the Dark Matter Problem: A

    Why this is right

    The Dark Matter Problem is an allusion to the missing mass, which cosmologists call "dark matter". They are trying to figure out what dark matter is (what is all this missing mass), and neutrinos could potentially account for up to 1/5 of the missing mass. Hence, it's only a partial solution to the missing mass problem.

    Skill tested: Main Point · how this choice captures the passage's function is the move to repeat next time.

  3. Wrong Takeaway1% picked this

    “Too Little, Too Late: Why Neutrinos Do Not Constitute

    This is focused on the correct central topics, but it doesn't match the end of the passage. The author is presenting physicists as being somewhat optimistic that neutrinos do have some mass and thus are a decent chunk of "dark matter", the missing mass. This title is too negative and dismissive. Neutrinos fail to explain all the missing mass. But they are still thought to be part of the missing dark matter.

  4. Wrong Emphasis: lacks central topic2% picked this

    “The Role of Gravity: How Dark Matter

    The central topic was neutrinos, not gravity. The discussion of gravity in the beginning was just to introduce us to this big question in physics, "observable matter is only 10% of the matter we think there is, so what is this 90% dark matter?"

  5. Too Narrow6% picked this

    “The Implications of Oscillation: Do Neutrinos Really

    This title fairly captures what's going on in the 3rd paragraph, but that's it. It doesn't appreciate the whole discussion of neutrinos serves this larger goal of answering the question, "What's up with this missing dark matter?"

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