Before the 1920s, there was a long-standing debate about the nebulae

Question

New Project RC Butler 2019  -  Practice 2 RC Passages Everyday   
Passage # 219, Date : 21-Jul-2019
 This post is a part of New Project RC Butler 2019 .  Click here for Details

Before the 1920s, there was a long-standing debate about the nebulae that are visible between galaxies. When viewed from a terrestrial telescope, they appear to be gas and dust emissions. In 1927, however, the team of Edwin Hubble theorized that these nebulae are actually star systems.

The bulk of Hubble’s evidence came from the analysis of gamma rays in the range of invisible light called 10^19 Hz. Hubble theorized that the arrival of these rays onto the earth’s surface was consistent with the most up-to-date knowledge about the collapse of a distant star system called 7.8ART. Existing data reveals that 7.8ART went Supernova roughly 27 billion years ago. Hubble’s team argued that the arrival of gamma rays in the 10^19 Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history.

There continues to be some doubt surrounding Hubble’s theory, however. Some scientists point out that the origins of gamma rays landing on earth today are not easily determined, because the expanding nature of the universe means that the radiation has traveled farther than Hubble’s calculations suggest. However, Hubble’s team did provide an answer to that objection by stating that the expanding universe theory applies mainly to its edges, and not within its center, which is the previous home of 7.8ART.

The skeptics’ most powerful objection to Hubble’s hypothesis is the argument that had the rays traveled for 27 billion years, it is unlikely that their trajectory would have been linear, due to the curvature of the known universe. Hubble’s team, however, pointed out that the curvature of the universe has no measurable effect on the path taken by gamma rays, because they are not affected by the gravitational pull of star systems in the same way as are celestial bodies.   1 
 C 
 1. The primary purpose of the passage is to

a. propose new methods for studying the ages of ancient star systems
b. rewrite a hypothesis regarding the trajectory of gamma rays
c. reconcile competing hypotheses regarding the expansion of the universe
d. evaluate a new hypothesis regarding the life cycle of 7.8ART
e. describe a controversy surrounding 7.8ART and its origins

2 
 D 
 2. The passage suggests that Hubble’s team would agree with which of the following regarding the gamma rays that land on earth today?

a. These rays are not likely to have originated on 7.8ART.
b. These rays have probably been on earth for more than 27 billion years.
c. These gamma rays are unlikely to have been produced during a Supernova.
d. It is impossible to determine the precise distance traveled by gamma rays that originate at the edge of the universe. 
e. These gamma rays are likely to accelerate as they approach the center of the universe.

3 
 B 
 3. The passage asserts which of the following about the claim that 7.8ART went Supernova roughly 27 billion years ago?

a. It was initially hypothesized by Edwin Hubble.
b. It is not widely disputed. 
c. It has been questioned by some of Hubble’s critics. 
d. It has been refuted thanks to recent work on gamma rays.
e. It is incompatible with the fact that the earth is now receiving gamma rays in the 1019 Hz frequency spectrum.

Sajjad1994 · Answer

I have taken 6 minutes (3 minutes to read the passage and 3 minutes for 3 questions), got last question wrong, i didn't understand the logic behind the correct answer choice. generis please gave us your precious time to explain this passage.

Thanks and regards

Thanks and regards

warrior1991 · Answer

SajjadAhmad

The answer to question#3 can be given after reading the 2nd para closely.

question#3

Read the lines colored in blue. It says that existing data reveals that 7.8ART went Supernova roughly 27 billion years ago.
Now in the whole paragraph and even in the subsequent paragraphs their is no mention to counter this statement.

Come to answer choices now

No it was not hypothesized by him. He gathered existing data.

Yes, this is something true because no counter has been made to the existing data in para#2.

NO, they did not question this but used this to tell about gamma rays.

Not refuted. Incorrect choice.

Wrong choice . It is not incompatible.

IMO B.

Srija221 · Answer

Why C is the correct answer for Q1?

Posted from my mobile device

Sajjad1994 · Answer

Explanation

1. The primary purpose of the passage is to

Difficulty Level:   750

Explanation

POE is useful in this question . Take a look at answer choices

(A)  is wrong because there is no new method has been purposed or discussed in the passage

(B)  is wrong because hypothesis are discussed but not rewriting is available

(C)  is correct because first para provide one hypothesis second para provide another hypothesis and in subsequent paragraphs these hypothesis compete with each other and reconciled in the last paragraph so this answer choice truly click the main purpose

(D)  This information has been discussed in the passage but in fraction. It didn't click the main purpose of the passage

(E)  Same as  D  It didn't click the main purpose of the passage

Answer: C

Hope it helps

Srija221 · Answer

Can anyone please explain the passage map of this passage?

My passage map- 1st para- Introduction of Hubble's theory 
2nd para- Evidence given by the Hubble's team against possible counter argument.
3rd para-same as 2nd para 
4th para-same as 2nd para

Posted from my mobile device

generis · Answer

SajjadAhmad , your time seems to be right on track. I don't take notes in RC the way most people do. I don't summarize paragraphs, though I did so here in "paragraph summaries" section. I make a map, a flowchart. I have provided both paragraph summary and my map in this post. Questions 1, 2, and 3 follow. You know, someone needs to figure out how to make these questions easier to answer. Formatting? /end rant Speaking of rants, I don't rant enough. /almost end rant I don't write sentences. I don't summarize paragraphs. I make maps that resemble . . . flow charts. I make boxes and circles. I draw arrows. I use many fewer words than you see here. I use abbreviations. Hope this analysis helps. ************************************************************ PASSAGE - paragraph summaries P1 -- Visible clouds between galaxies seem to be composed of gas and dust . -- 1927: Hubble, theory: no. Nebulae are star systems P 2 Most of Hubble's evidence: Arrival time (age) of gamma rays on Earth is consistent with time of Supernova BART collapse. It exploded and ejected star material. P 3 People doubt Hubble: gamma rays’ origins? Hard to know→ Expanding universe = Distance traveled is uncertain. Hubble’s answer: “expanding universe” theory applies to edges of universe. BART was in center P 4 Strongest objection to Hubble theory: gamma rays’ trajectory probably was not linear. Spacetime is curved. Age may not be 27 billion years. Hubble’s answer: curved universe and gravity do not affect gamma rays. ************************* MAPPING THE NEBULAE PASSAGE My version of taking notes in RC. If summarizing paragraphs works for you, do not change. ROUGHLY: Paragraphs 1 and 2 are in blue , in the upper half of the page. Paragraphs 3 and 4 are in two sets of statements in RED and GREEN, lower half of the page. CRITICS: HUBBLE RC - nebulae - hubble - july 2019.jpg

generis · Answer

Question 1  The primary purpose of the passage is to

A). propose new methods for studying the ages of ancient star systems
B) rewrite a hypothesis regarding the trajectory of gamma rays
C) reconcile competing hypotheses regarding the expansion of the universe
D) evaluate a new hypothesis regarding the life cycle of 7.8ART
E) describe a controversy surrounding 7.8ART and its origins

Srija221  - here is an explanation for Q 1.
• see my map. Basic outline: 
Subject → background
→→→Hubble theory and evidence
Objection
Answer
Objection
Answer

• look at the   verbs

This passage does not
A)  propose  new methods or
B)  rewrite  a hypothesis
Eliminate A and B

• look at subject matter

D) evaluate  a new hypothesis  - no new hypothesis mentioned
E) describe a controversy surrounding  7.8ART and  its origins   - 
-- no new hypothesis mentioned. Eliminate D
-- controversy, yes, but not about BART and its  origins. 
The controversy is about nebulae and whether BART gamma rays could have reached Earth (and created star systems?). 
BART's origin is not at issue.

• By POE, the answer is C:   reconcile competing hypotheses regarding the expansion of the universe

Hmm. That answer does not look great initially. 
-- This passage does seem to be reconciling two views
-- but initially I was not happy with "expansion of the universe." I dug a little deeper. Expansion of the universe may or may not be the central topic, but the author does spend a lot of time talking about two views of exactly that.

The main clash of viewpoints does not seem to be about the expansion of the universe.
The central quarrel, though, does  involve  the expansion of the universe.

Passage? 
Objection to Hubble, #1: Hubble's evidentiary gamma rays traveled farther than 27 billion years b/c of  expanding universe 
Hubble's answer to #1:  Expansion of universe  applies to edges of universe. BART was in the center.

Objection to Hubble, #2: 27 billion years is not accurate.  Spacetime is curved. Gamma rays did not travel in linear fashion. 
Hubble's answer to #2:  Curvature of spacetime  and gravitational have  no measurable effect  on gamma rays

Option (C) is better than I thought and quite a bit better than the other options.   
There IS an argument about the expansion of the universe going on, albeit in the context of a debate about the composition of nebulae between galaxies, about which we do not hear much more.

ANSWER C

generis · Answer

2. The passage suggests that Hubble’s team would agree with which of the following regarding the gamma rays that land on earth today?

Opposite. Hubble team would DISAGREE:
7.BART is precisely where the gamma rays originated according to Hubble's team.

Passage:  ... 7.8ART went Supernova roughly 27 billion years ago.  Hubble’s team argued that the arrival of gamma rays in the 10^19 Hz spectrum  are  IS consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history.

No. Hubble team would DISAGREE. 
Hubble team, as just mentioned in para 2, says that gamma rays' age is consistent with BART going Supernova 27 B years ago.
 Critics  say that rays are probably older because of expanding universe and curved spacetime. Hubble has an answer for both.

Opposite: Hubble team theorized that the gamma rays on Earth matched the time of . . . the explosion of a Supernova.

Passage:  Existing data reveals that 7. 8ART went Supernova  roughly 27 billion years ago. Hubble’s team argued that t he arrival of gamma rays  in the 10^19 Hz spectrum are  consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history.

Yes, Hubble team would AGREE. 
Critics: expanding universe means that radiation travels   farther than Hubble's calculations suggest.
Hubble: expanding universe theory applies  , but only at the edges of the universe.  
Hubble conceded the point about the expanding universe theory at the edges. 
Expanding universe theory = hard to measure distance traveled. (The gamma ray is moving but space itself is expanding at the same time.)
Passage:
 Some scientists point out that the  origins  of gamma rays landing on earth today are not easily determined , because the  expanding nature of the universe  means that the radiation has traveled farther than Hubble’s calculations suggest.

Passage: Hubble’s team  did provide an answer to that objection by stating that the  expanding universe theory applies mainly to its edges. 
Okay, so apply critics' observation to edges: universe expands as gamma rays travel, making distances hard to measure.
 
Take one second to decide that this is a throwaway.
Not one mention of gamma rays traveling towards the center of the universe.
Hubble team says that expanding universe theory applies at edges, not at center.
(Things travel more slowly at the expanding edges. Counterpart: travel more swiftly at center? 
Hubble: no. Expanding universe theory does not apply to center of universe. 
 
 The answer is D.

generis · Answer

3. The passage asserts which of the following about the claim that  7.8ART went Supernova roughly 27 billion years ago ?

Find the part of the passage that matters. Paragraph 2
   was consistent with the most up-to-date knowledge about the collapse of a distant star system called 7.8ART. Existing data reveals that 7.8ART went Supernova roughly 27 billion years ago. . . .

No. Hubble theorized about gamma rays on Earth

.
Probably the answer.  "Existing data"   reveals that 7.BART went Supernova roughly 27 billion years ago. 
Declarative statement.
No hedging. No qualifiers. No doubters. 
  Existing data reveals   sounds conclusive and confident. Not disputed.

No. Hubble's critics question whether the gamma rays on Earth got here from BART. No more than that issue.

Two seconds to read: bye. No mention of recent work on gamma rays.
No refutation about when BART went Supernova. The objections are about the age of the gamma rays.

REJECT. Simple maps are good. I leave off details such as this one.

1019 Hz frequency spectrum? (This sounds like some horrible new app for my phone.)

Think: No, this logic is exactly backwards. The critics think that the gamma rays are not necessarily consistent with BART's having gone Supernova.
The critics do not dispute the Supernova. They dispute whether and how gamma rays on earth can be explained by the explosion of BART. 
No one objects to: BART went supernova 27 billion years ago. That fact is not "incompatible" with anything.

The correct answer is (B).

generis · Answer

Srija221  , I mapped the passage in two ways in my post,  HERE

I would recommend pasting the passage into a document and printing it as you read answers.
It is very difficult to keep a passage organized without being able to see it.

The third and fourth paragraphs are not the same as the second paragraph.
The third and fourth paragraphs are not the same as each other.

On my drawing (which is a slightly expanded version of what I actually wrote), paragraphs 3 and 4 are in    RED   and   GREEN  , lower left.

Hope that helps.

navderm · Answer

Can you explain this one : 
The Option D states : "It is impossible to determine the precise distance traveled by gamma rays that originate at the edge of the universe". 
The passage, according to me, states that it might have a different calculation but it's not straight forward if gamma rays are originating from edge of the universe.

"It is impossible" seems blatantly incorrect to me.

From the passage : 
Some scientists point out that the origins of gamma rays landing on earth today are not easily determined, because the expanding nature of the universe means that the radiation has traveled farther than Hubble’s calculations suggest.

This clearly states "not easily determined'. That is very very different from "It is impossible".

generis

bM22 · Answer

Hi  navderm ,

If I may.

I think what the line: "Some scientists point  out that the origins of gamma rays landing on earth today are not easily determined,  because the expanding nature of the universe means that the radiation has traveled farther than Hubble’s calculations suggest." means is the distance the gamma rays have travelled is difficult to measure are the the universe is in constantly expanding.

Now what option D states: 
 
Which is correct. We need to look at the complete sentence, as to what is impossible. As mentioned, it is impossible to determine the  precise  distance traveled by gamma, because of the expanding nature of the Universe.

Hope This Helps.
Thanks.

Waldfee124 · Answer

I agree with everything you say, but I cannot agree with the answer choice. The passage's primary purpose is maybe about hypotheses but it is most definitely not about hypotheses  regarding the expansion of the universe !!

MuskaanMittal · Answer

QUESTION 1

This is a primary purpose question, as indicated by the phrase primary purpose. The task of the question is to determine why the author wrote the passage. The subject of the question is the passage as a whole. In order to answer the question, determine why the author wrote the passage, then evaluate the answer choices, eliminating any choice that does not match the author’s primary purpose. The passage introduces a long-standing debate and the theory of the team of Edwin Hubble. The passage describes Hubble’s evidence and the doubt surrounding Hubble’s theory. However, Hubble’s team did provide an answer to that objection, and in the final paragraph, Hubble’s team countered the skeptics’ most powerful objection. Therefore, the passage is most concerned with describing and resolving contradictory hypotheses.

Choice A: No. This answer may seem appealing because the passage mentions 7.8ART went Supernova roughly 27 billion years ago and a corresponding time in galactic history. However, this is a memory trap. The passage does not propose new methods, but rather discusses Hubble’s hypothesis and responses to skeptics.

Choice B: No. This answer may seem tempting because of the recycled language trajectory and gamma rays. However, the passage does not rewrite a hypothesis. Rather, the passage discusses the skeptics’ most powerful objection to Hubble’s hypothesis and Hubble’s response to this objection.

Choice C: Correct. The passage introduces a long-standing debate and the theory of the team of Edwin Hubble. The passage describes Hubble’s evidence and the doubt of some scientists. However, Hubble’s team did provide an answer to that objection, and in the final paragraph, Hubble’s team countered the skeptics’ most powerful objection. Therefore, the passage is most concerned with reconciling competing hypotheses.

Choice D: No. This answer may seem appealing because of the recycled language 7.8ART. However, the new hypothesis does not concern the life cycle of 7.8ART. The passage states Hubble theorized that the arrival of these rays onto the earth’s surface was consistent with the most up-to-date knowledge about the collapse of a distant star system called 7.8ART. The new hypothesis is concerned with whether nebulae are actually star systems.

Choice E: No. This answer may seem tempting because the passage states 7.8ART went Supernova roughly 27 billion years ago. However, this answer is a memory trap. Hubble’s team does not debate 7.8ART and its origins. The passage states Hubble’s team argued that the arrival of gamma rays in the 1019 Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history, in the attempt to prove that these nebulae are actually star systems.

The correct answer is choice C.

QUESTION 2

The phrase the passage suggests in the question stem indicates this is an inference question. The task of the question is indicated by the phrase Hubble’s team would agree with which of the following. The subject of the question is gamma rays that land on earth today. In order to answer the question, determine what the passage states about the subject and evaluate the answer choices, eliminating any choice that cannot be supported by the text. The passage states Hubble’s evidence came from the analysis of gamma rays...Hubble theorized that the arrival of these rays...was consistent with the most up-to-date knowledge about the collapse of...7.8ART. The passage also states some scientists point out that the origins of gamma rays...are not easily determined, because the expanding nature of the universe means that the radiation has traveled farther than Hubble’s calculations suggest. Hubble’s team responded by stating that the expanding universe theory applies mainly to its edges, and not within its center, which is the previous home of 7.8ART.

Choice A: No. This answer may be appealing because the passage states that some scientists point out that the origins of gamma rays landing on earth today are not easily determined. However, this answer choice is a reversal. The passage also states Hubble’s team argued that the arrival of gamma rays in the 1019 Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART.

Choice B: No. This answer may be tempting due to the recycled language 27 billion years. However, this answer choice is a memory trap. The passage states that Hubble theorized that the arrival of these rays onto the earth’s surface was consistent with the most up-to-date knowledge about the collapse of a distant star system called 7.8ART. Existing data reveals that 7.8ART went Supernova roughly 27 billion years ago. Furthermore, the passage discusses how the rays traveled for 27 billion years.

Choice C: No. This answer may be appealing because the passage states some scientists point out that the origins of gamma rays landing on earth today are not easily determined. However, this answer is a reversal. The passage states that Hubble’s evidence came from the analysis of gamma rays...and Hubble theorized that the arrival of these rays onto the earth’s surface was consistent with the most up-to-date knowledge about the collapse of a distant star system called 7.8ART which...went Supernova roughly 27 billion years ago.

Choice D: Correct. The passage states that some scientists point out that the origins of gamma rays...are not easily determined, because the expanding nature of the universe means that the radiation has traveled farther than Hubble’s calculations suggest. Hubble’s team responded by stating that the expanding universe theory applies mainly to its edges, and not within its center, which is the previous home of 7.8ART.

Choice E: No. This answer may be tempting because of the recycled language center. However, accelerate is extreme language. The passage states Hubble’s team...pointed out that the curvature of the universe has no measurable effect on the path taken by gamma rays, because they are not affected by the gravitational pull of star systems in the same way as are celestial bodies.

The correct answer is choice D.

QUESTION 3

The phrase asserts which of the following in the question stem indicates this is a retrieval question. The task of the question is indicated by the words asserts. The subject of the question is the claim that 7.8ART went Supernova roughly 27 billion years ago. In order to answer the question, determine what the passage states about the subject and evaluate the answer choices, eliminating any choice which cannot be supported by the text. The passage states that existing data reveals that 7.8ART went Supernova roughly 27 billion years ago. The passage continues that Hubble’s team argued that the arrival of gamma rays in the 1019Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history.

Choice A: No. This choice is a memory trap. The passage states that Hubble theorized that the arrival of these (1019Hz) rays onto the earth’s surface was consistent with the most up-to-date knowledge about the collapse of a distant star system called 7.8ART then indicates that existing data reveals that 7.8ART went Supernova roughly 27 billion years ago. However, the passage does not indicate whether Hubble was using the same data as exists now, or whether he theorized that the collapse occurred 27 billion years ago.

Choice B: Correct. The passage states that existing data reveals that 7.8ART went Supernova roughly 27 billion years ago. While the remainder of the passage discusses some doubt surrounding Hubble’s theory, the passage is referring to his theory that the arrival of gamma rays in the 1019Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history, not a theory about the timing of the 7.8 ART going Supernova.

Choice C: No. This is a memory trap. While the passage discusses some doubt surrounding Hubble’s theory, the passage is referring to his theory that the arrival of gamma rays in the 1019Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history, not his theory about the timing of the 7.8 ART going Supernova.

Choice D: No. This is a memory trap. While the passage discusses some doubt surrounding Hubble’s theory, the passage is referring to his theory that the arrival of gamma rays in the 1019Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history, not a theory about the timing of the 7.8 ART going Supernova. Additionally, refuted is extreme language. The final paragraph discusses skeptics’ most powerful objection but also provides a response from Hubble’s team.

Choice E: No. This is a memory trap. While the passage discusses some doubt surrounding Hubble’s theory, the passage is referring to his theory that the arrival of gamma rays in the 1019Hz spectrum are consistent with star materials having been ejected from the region of 7.8ART at a corresponding time in galactic history, not a theory about the timing of the 7.8 ART going Supernova. Additionally, incompatible with is extreme language. The third paragraph notes that some scientists point out that the origins of gamma rays landing on earth today are not easily determined, because the expanding nature of the universe means that the radiation has traveled farther than Hubble’s calculations suggest. However, the paragraph then notes that Hubble’s team did provide an answer to that objection.

The correct answer is choice B.

RohitSharma001 · Answer

IN Q1, Should the answer not be E? It does debate over the origins.

egmat · Answer

RohitSharma001

Looking at your doubt about option E, I can see why the word "debate" caught your attention - you're absolutely right that there IS a debate in the passage! However, you've misidentified what the debate is actually about, which is a common trap in RC primary purpose questions.

Why Option E is Incorrect:

The key issue is understanding  what  the controversy is about:

Option E states:  "describe a controversy surrounding 7.8ART and its origins"

But the passage actually describes:  A controversy about  Hubble's theory that nebulae are star systems

Process Diagnosis - Where the Confusion Arose:

You correctly identified that there's a debate/controversy in the passage. However, you focused on 7.8ART because it appears multiple times. This is a classic RC trap - confusing  supporting evidence  with the  main topic .

Here's the passage structure:
 
 Para 1: Introduces the  main topic  - Hubble's theory about nebulae 
 Para 2: 7.8ART is introduced as  evidence  for Hubble's theory 
 Para 3-4: Objections to Hubble's theory (not to 7.8ART itself!)

Notice that 7.8ART is never debated - everyone agrees it went supernova 27 billion years ago. The debate is whether gamma rays from 7.8ART  prove Hubble's theory about nebulae .

Strategic Insight - The "Supporting Evidence Test":

When you see a proper noun (like 7.8ART) appearing frequently in an RC passage, ask yourself:
 
  Is this the main topic?  (What the passage is fundamentally about) 
  Or is this supporting evidence?  (Used to prove/disprove the main topic)

Quick test: If you remove 7.8ART and replace it with "Star System X," does the passage still make sense? Yes! Because 7.8ART  Pattern Recognition for Similar Questions: 
 
In GMAT RC primary purpose questions, wrong answers often:
- Focus on a specific example rather than the main argument
- Confuse supporting evidence with the central claim
- Misidentify what's being debated

You can practice similar questions  here  (you'll find a lot of OG questions) - select  Reading Comprehension  under  Verbal  and choose  Medium  level questions focusing on primary purpose.

Before the 1920s, there was a long-standing debate about the nebulae

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GMAT Reading Comprehension (RC) Questions

Before the 1920s, there was a long-standing debate about the nebulae

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

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From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards