LSAT 132 | Section 2 | Logical Reasoning: Q20

LR Question 20 Explanation

QUESTION TEXT: Astronomer: Earlier estimates of the distances of…

QUESTION TYPE: Paradox

PARADOX: The stars are older than the universe, which can’t be true. If the new calculations are right, the stars are further away and intrinsically brighter than we thought.

ANALYSIS: This situation isn’t really a “paradox”, but I’ve kept the same name for the question type.

According to our old calculations, the stars are older than the universe. This is obviously impossible. The astronomer says the new calculations indicate the stars are younger, thus resolving the paradox. We have to explain how the new information means the stars are younger. We know two new things about the stars:

1. They are further away than we thought.
2. They are brighter than we thought.

One of these facts must show that the stars are not as old as we thought. That’s the only way that this new information can prove the stars aren’t older than the universe.

___________

1. Useless. This has nothing to do with the astronomer’s calculations. We’re trying to explain how the calculations show the stars are younger than we thought.
2. It doesn’t matter how old the universe is. However old it is, we want explain why the stars are less old.
3. CORRECT. The astronomer found that the stars are brighter than we thought. So this answer shows that the stars are also younger than we thought.
4. Tempting, but useless. This answer refers to the wrong concept. We’re still on earth. The stars appear just as bright as they always have.
   The astronomer’s calculations show that the stars are actually brighter than we thought. Intrinsic brightness refers to how bright stars really are, not how bright them appear to be.
5. So what? We’re trying to explain how old the stars are. It doesn’t matter if we can see more stars. Whoop-dee-do. This has nothing to do with the astronomer’s findings.

Recap: The question begins with “Astronomer: Earlier estimates of the distances”. It is a Paradox question. To practice more Paradox questions, have a look at the LSAT Questions by Type page.