LR Question 13 Explanation
QUESTION TEXT: Astronomers have found new evidence that the number of…
QUESTION TYPE: Paradox
FACTS: Astronomers haven’t changed their estimates of the universe’s weight, even though we’ve discovered 40 billion more galaxies.
ANALYSIS: Shouldn’t more galaxies mean the universe is heavier? There are more stars, planets, etc.
Well, the right answer tells us that galaxies are only a small part of the universe. Sure makes you feel tiny.
___________
- CORRECT. This would do it. If Galaxies were only 0.0001% of the universe, then even 40 billion more galaxies wouldn’t add much weight.
- We found four times the number of galaxies that we thought existed. That should let us make at least a rough estimate of their weight: they’re probably heavy, compared to the galaxies we knew about.
- This explains why we found more galaxies, but it tells us nothing about their weight.
- This goes the wrong way. We’re trying to figure out why theories about the universe’s weight weren’t affected by the discovery of the new galaxies.
- One astronomer’s estimate might say the universe is twice as heavy as another astronomer’s estimate. But if both astronomers didn’t change their estimates, then we can say they agree that the new galaxies didn’t affect the weight of the universe, even if their estimates are different.
More Resources for Paradox Questions
- Intro Course lesson: This intro course lesson covers Paradox questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers paradox questions.
For D, I think Graeme meant to say “universe’s weight weren’t affected by the discovery about the new galaxies’ mass.”
Yes, that’s correct! Thanks for catching this. The page has been updated.
Hi Michelle!
In this case, we need to explain a lack of change in astronomer’s estimates.
(E) is definitely wrong, because it just doesn’t help to explain why the estimates remain unchanged. The answer doesn’t say that there was no consensus about the mass, only about the proper way to measure the mass. Even if every astronomer was using a different method to estimate the mass of the universe, the addition of 40 billion galaxies SHOULD change their estimates, regardless of how much their methods differ.
(A), on the other hand, explains this well – and as you pointed out, negating (A) weakens the argument, which does help you to see that the mass of galaxies related to the universe’s total mass is important. If the mass of galaxies was known to make up a large percentage of the mass of the universe, then a huge increase in number galaxies would definitely affect estimates.
Hope that helps!
I was stuck between A and E, and I see why A is a better choice but I still don’t really understand why E is wrong. The explanation doesn’t really make sense to me. Is it that you would need to make a jump between there being “no consensus” and the “total mass remain[ing] virtually unchanged” -when you shouldn’t need to “help” the correct argument in any way (?).
Oh and is it true that if you negate the correct answer choice that it would weaken the argument? I just noticed that if I do this A would be the only one that works.