#15 - Author's Perspective

[Tami Taylor]

Hello!

Can you help me understand why (C) is incorrect and (D) is correct? Here is what I think so far:

(C) is NOT the correct answer because the author does not harp on the need to find the "exact" mass of neutrinos -- just whether they have any mass at all. When the author discusses the new research findings in the 3rd and 4th paragraphs -- findings which are still largely theoretical and offer a range versus exact estimate of mass -- the author isn't critical of the lack of precision of these findings.

(D) is the correct answer because, in the first paragraph, the author talks about the theory of gravitation and gravitational force and, throughout the rest of the passage, casts no doubt on what has traditionally been believed about these concepts and references them during his/her discussion about whether neutrinos have mass (end of paragraph 2).

Thank you!

[Robert Carroll]

Tami,

I think that answer choice (C) can be decisively eliminated because of lines 47-49. The highest estimate of the mass of neutrinos would only account for 20% of the missing mass. At best, then, a small minority of the missing mass could be accounted for by neutrinos. Figuring out the exact mass of a neutrino would either confirm is makes up 20% of the missing mass (which is still far from solving the problem of the missing mass), or confirm it makes up less than that - 20% is the ceiling.

Lines 14-17 commit the author to thinking that the gravitational force exerted by bodies with mass is what causes things in the universe to cohere. Nothing in the later statements casts doubt on that - in fact, the author, in lines 28-30, is committed to the idea that lack of mass would be fatal for the neutrino's chances to explain things, because mass is needed for something to exert the force that explains galaxies (among other things). So, again, the author is staking out a position that makes gravity the cause of the existence of galaxies.

Robert Carroll

[Tami Taylor]

Hi Robert,

Thank you so much! This really helps.