GMAT RC: Hands-on Practice: Examples of ‘Predicting Test Points’ and ‘Structure Analysis’
Most attempts by physicists to send particles faster than the speed of light involve a remarkable phenomenon called quantum tunneling, in which particles travel through solid barriers that appear to(5) be impenetrable. (Definition of a proper noun with a modifier: may be tested in detail questions) If you throw a ball at a wall, you expect it to bounce back, not to pass straight through it. (Analogy/Example: may be tested in function questions)Yet subatomic particles perform the equivalent feat. (When you see the transition keyword ‘Yet’, first determine if there’s a shift in attitude: here there isn’t, it’s just making a comparison) (Comparison questions test similarities and differences)Quantum theory says that there is a distinct, albeit small, probability that such a particle(10) will tunnel its way through a barrier;(Appearance of a “theory”: may be tested in detail questions) the probability declines exponentially as the thickness of the barrier increases.(Appearance of a linear relationship between thickness and probability: may be tested in inference questions)
————-Context + Topic: Defining and Introducing Quantum Tunneling Effect————-
Though the extreme rapidity of quantum tunneling was noted as early as 1932, not until 1955 was it hypothesized—by Wigner and(15) Eisenbud —that tunneling particles sometimes travel faster than light. (When you see the concession keyword ‘though’, first determine if there’s an attitude: here there isn’t, it’s just comparing facts) (Comparison questions test similarities and differences) (Multiple years appearing: may be tested in detail questions) (Seeing people propose ideas: “W and E hypothesized”, may be tested in “Which of the following would W.E. agree with?” questions)Their grounds were calculations that suggested that the time it takes a particle to tunnel through a barrier increases with the thickness of the barrier until tunneling time(20) reaches a maximum; beyond that maximum, tunneling time stays the same regardless of barrier thickness. This would imply that once maximum tunneling time is reached, tunneling speed will increase without limit as barrier thickness(25) increases. (Seeing the linear relationship between tunneling time and barrier thickness: may be tested in inference questions)
————-Arg: Scholars W and E Propose Hypothesis————
(After the hypothesis is introduced, less than half of the article remains – there will be no further attitude shifts)
Several recent experiments have supported this hypothesis that tunneling particles sometimes reach superluminal speed. According to measurements performed by Raymond Chiao and colleagues, for example, photons can pass through(30) an optical filter at 1.7 times the speed of light. (Evidence, example: tested for function)
————-Eval: Introducing Experimental Support—————
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