Reading Comprehension

PT121 · S2 · P3 · Q15 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.

15.

Based on the passage, the author most likely holds which one of the following views?

Observable matter constitutes at least
Opposite
Observable matter is only adding up to 10% of the mass. The missing 90% is "dark matter", i.e. not directly observable.
4% picked this
Current theories are incapable of
Unsupported: incapable
The force that causes all particles in the universe to attract is gravity. Is this author saying gravity turns out to be wrong and current theories can't figure what force really does attract particles to another? No, it's saying that they presume gravity is still a correct theory; they're just seeking to find the missing mass so that what we already think of gravity would then successfully account for the shape of structures. If scientists weren't still convinced that gravity was right, they wouldn't be hunting for the missing mass. They would instead accept that the 10% observable matter is really more like 100% of the universe, and figure out a way besides gravity to account for the shapes of galaxies and clusters.
35% picked this
The key to the problem
Too Strong: the key
The author would agree that determining the mass is important, but since the upper limit of potential mass for a neutrino is still only going to account for 20% of the 90% dark matter conundrum, it's too strong to say that "THE key to solving dark matter is the exact mass of a neutrino".
7% picked this
Correct
It is unlikely that any
Why this is right
This is a tough answer to find explicit support for, because the support comes more from what the author didn't say. This relates back to our reasons for rejecting (B) -- the author and the physics community are implicitly accepting that the theory of gravitation is not the problem, not the reason why our calculations only add up to 10% of what we've predicted. The search for the missing 90% is sort of predicated on the assumption that gravitational theory is right. If gravitational theory successfully explains the shapes of the universe, but only if the universe has, say, 100 zillion tons of matter, then when we find out that the observable universe is only 10 zillion tons of mass, we have two options of resolving that: - gravitational theory is wrong to predict 100 zillion or - gravitation theory is right to predict 100 zillion, and we just need to figure out where the other 90 zillion is. Since the passage proceeds from the 2nd assumption, it seems fair to say that neither the author nor physicists are really actively pursuing the idea that gravitational theory is wrong. Even the author's final paragraph accepts that the problem is the missing mass, not gravity's predicted total mass of 100 zillion. - "neutrinos could only account for about 20 percent of the universe's missing mass" implicitly accepts that there is missing mass. - "it may add to our understanding of the role elementary particles play in holding the universe together" is an allusion to the gravitational force, again implying that we just need to find the missing mass to bring it into accordance with gravity's predictions.
Skill tested: Author Opinion · how this choice captures the passage's function is the move to repeat next time.
48% picked this
Neutrinos probably account for most
Contradicted
It says the max they would account for is 20% of the missing mass.
6% picked this

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