Reading Comprehension

PT121 · S2 · P3 · Q14 Neutrinos

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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.

(Written summary below video)

Topic

Neutrinos and the Dark Matter mystery

Frameworks

Problem / Solution Answer a Question

Main Point

Question / Problem The observable matter in the universe only adds up to about 10% of the mass that would be needed for gravity to account for the observable structures in the universe. So given that we believe in gravity, and we believe we're correctly observing structures, where is the other 90% of the universe's mass?

Answer / Solution Neutrinos seem to account for about 20% of it, but more broadly the discovery that a tiny particle's crazy small mass might still add up to something significant (because of how numerous that type of particle is) is making scientists think that maybe the tiny masses of elementary particles is a big part of the missing mass.

Summary

P1 - Background on gravity, introduction to Curious Problem

After briefly summarizing what gravity means, this paragraph establishes the 90% missing matter conundrum, and says that cosmologists have postulated something called 'dark matter', which seems to just be a placeholder name.

P2 - A potential Solution that seemed non-viable

This paragraph introduces neutrinos as one possible answer/solution that cosmologists had considered, but ultimately rejected since they assumed that neutrinos had no mass.

P3 - New research brings back hope to possible Solution

This paragraph presents new research that suggests that neutrinos do have mass, so they're back as a contender for this dark matter problem we're trying to solve.

P5 - Implications of New research

The author's take on where we're at usually comes in the final paragraph of Science passages. Here, it sounds like neutrinos are promising as a Partial Solution, and they're also opening up new lines of inquiry that are potentially an encouraging step forward in the process of trying to find the Whole Solution.

Topic

The search for "dark matter" and the possible role of neutrinos in accounting for missing mass in the universe.

14.

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

  1. “The Existence of Dark Matter:

    Wrong Emphasis: lacks central topic

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

    2% picked this

  2. Correct

    “Neutrinos and the Dark Matter

    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.

    88% picked this

  3. “Too Little, Too Late: Why

    Wrong Takeaway

    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.

    1% picked this

  4. “The Role of Gravity: How

    Wrong Emphasis: lacks central topic

    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?"

    2% picked this

  5. “The Implications of Oscillation: Do

    Too Narrow

    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?"

    6% picked this

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