Q23

[danitay]

Hi, I'm stuck on this question and would really appreciate your help. I was torn between answers B and D.

B: I thought this answer was stronger, because I thought the passage was primarily concerned with reasons the wave theory was discredited (the first paragraph beings with, "the classical wave theory of radiation began to encounter obstacles" and then the passage lists some of the obstacles like the blackbody object experiments, Planck, Einstein, etc)

D: This is the correct answer, but I thought it was weak because 1) the passage never explicitly states that examining the evolution of theories is the purpose; 2) the phrase "evolution of theories" with "theories" plural was confusing. Either there is only one theory that evolves (theory of radiation) or there are multiple theories in which case "evolution" doesn't really make sense; and 3) "evolution" seems inappropriate to describe what happened. Wave theory and quantum theory are two totally different ideas, and the last sentence says quantum theory was a "new vision in physics"

What am I missing? Thank you for all your help!

[bbirdwell]

(D) is better than (B) for a few reasons. First of all, the passage is more descriptive than a "summary," it's more of a story. Furthermore, I think the emphasis is more on the new direction than the rejection of the old -- the old is just used as a starting point for understanding the new.

The evolution of theories is certainly there -- classical wave, Planck's hypothesis, Einstein and others' theoretical justification, and the "new theories" mentioned in line 61. The "physical phenomenon" mentioned in (D) refers to radiation. It was a critical stage in that evolution because it was the end of the classical wave era and the beginning of something else.

[danitay]

Ah, thank you very much! Now I see it.