Reading comp PrepTest 152 · Section 3 · Question 20

Topic: Science

Paragraph 1

• Paragraph note
  • Background info on Big Bang
• Views, minor Meta-Structures, and the author's attitude
  • Definition of "Big Bang": Hot, dense, small universe underwent rapid, massive inflation; has since cooled (first through last sentences)

Paragraph 2

• Paragraph note
  • Carroll and Chen's view: Big Bang was not a unique event, but one of many in the "multiverse"
• Views, minor Meta-Structures, and the author's attitude
  • Definition of "multiverse": Larger Universe that encompasses everything, including stuff that is beyond our perception (last sentence)
  • Carroll, Chen, and some physicists' view:
    • Big Bang was the beginning of our universe, but not the multiverse (last sentence)
    • Big Bangs occur periodically across an extended period (first sentence)

Paragraph 3

• Paragraph note
  • Background info on entropy/second law of thermodynamics
• Views, minor Meta-Structures, and the author's attitude
  • Definition of "second law of thermodynamics": Entropy naturally increases with time (second sentence)
  • Definition of "entropy": Measurement of disorder (second sentence)
  • Example that illustrates why entropy increases over time:
    • Moving an object in a room at random will tend to make the room less orderly, as there are more places for the object that would make the room less orderly (fifth through last sentence)

Paragraph 4

• Paragraph note
  • Question: Why was the universe small, hot, and dense before the Big Bang?
• Views, minor Meta-Structures, and the author's attitude
  • Carroll and Chen view:
    • The universe's most common starting condition before Big Bang is a cold, empty space — but that would make massive inflation unlikely (last sentence)
  • Author's attitude: "mystery" (first sentence), "unlikely configuration" (second sentence), "innovation" (last sentence)

Paragraph 5

• Paragraph note
  • Answer: Big Bang was the product of an energy fluctuation
• Views, minor Meta-Structures, and the author's attitude
  • Cause-and-effect relationship, according to Garriga and Vilenkin:
    • Energy fluctuations in empty spaces can cause big bangs in empty areas (second sentence)
  • Carroll and Chen view:
    • Our universe, and others, were created by these energy fluctuations in a highly disordered universe

Paragraph 6

• Paragraph note
  • Implication: Big Bang is not that unlikely, given the vastness of the universe; many Big Bangs probably occurred
• Views, minor Meta-Structures, and the author's attitude
  • Author's attitude: "not that unlikely" (first sentence)

Main Point: Carroll and Chen argue that the Big Bang occurred due to an energy fluctuation in a highly disordered space.

Paragraph 3, Sentence 3 (P3, S3) - Definition of entropy/second law of thermodynamics

P4, S2-3 - Question posed

P5, S3 - Question answered

Question/Answer: The Question/Answer Meta-Structure best fits the argument made in this passage. This passage spends three paragraphs providing a rudimentary understanding of entropy, the second law of thermodynamics, and the "multiverse." Once that groundwork is laid, the author presents a mystery in the fourth paragraph. This mystery can be easily framed as a question: Why was the universe small, hot, and dense before the Big Bang ... um .... banged (P4, S1)? As the author points out, this is an unlikely state, given the tendency for systems to become more entropic (colder and emptier) over time (P4, S2). In the following paragraph, we get the answer. Carroll and Chen argue that energy fluctuations likely led to the Big Bang (P5, S3). As far as we can trace this answer, such an energy fluctuation would have momentarily changed the cold, empty (high entropy) space into small, hot, and dense (low entropy) space that led to the Big Bang.

In a Question/Answer passage, the main point is generally the answer with which the author agrees. Here, the author agrees with Carroll and Chen's explanation. So, the main point is that energy fluctuation would have momentarily changed the cold, empty (high entropy) space into small, hot, and dense (low entropy) space that led to the Big Bang.

Causality: Science passages in Reading Comp cover many different topics. But they usually attempt to prove that some cause-and-effect relationship exists. By simplifying challenging science passages to a short description of the cause-and-effect relationship, we'll confirm that we understand the passage and make answering the questions much easier.

In this passage, the answer to the question posed is a cause-and-effect relationship. Carroll and Chen argue that random energy fluctuations on a subatomic scale caused the Big Bang by converting a cool, empty space into a hot, small, and dense space. Do we need to understand what "random energy fluctuations on a subatomic scale" are? Reader, we do not. But knowing that this is the cause and the Big Bang is the effect is a sufficient amount of information effect to answer the questions.

This passage has the reputation of being particularly unfriendly to test-takers — especially those of us who aren't science-fluent. From the beginning, the passage tries to scare us off with an onslaught of abstruse terms — "infinitesimally," "entropy," "thermodynamics," "multiverse," "cosmic bubble."

However, three things can make this passage much easier to understand. The first is the rhetorical question posed in the fourth paragraph, which is discussed in the Meta-Structure section above.

Secondly, this passage can be reduced to a cause-and-effect relationship, like many science-themed passages. This is also covered extensively in the Meta-Structure section above.

Finally, the passage helps us by using an analogy in the third paragraph. In many difficult Reading Comp passages, analogies will make rarefied concepts easier to understand. These analogies make these concepts more comprehendible by relating the idea to something we know about. Here, the analogy clarifies why low entropy states are unlikely. If you randomly moved items in your room, the room would probably get more disordered (entropic) over time. The universe works, by analogy, in similar ways (P3, S4-6). Understanding analogies is very important. If we read an analogy but have trouble determining its relation to the passage's topic, we should try to reread the paragraph until we can make sense of the analogy. If we don't understand the analogy, we will have a tough time understanding anything that follows.