Reading ComprehensionDifficulty: Hard

PT128 S1 P4 Q23 Explanation

Riddled Basins of Attraction

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsLocal PurposeScience

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Passage

One of the foundations of scientific research is that an experimental result is credible only if it can be replicated—only if performing the experiment a second time leads to the same result. But physicists John Sommerer and Edward Ott have conceived of a physical system in which even the least change in describing the motion of a particle placed in a particular type of force field.

Sommerer and Ott based their system on an analogy with the phenomena known as riddled basins of attraction. If two bodies of water bound a large landmass and water is spilled somewhere on the land, the water will eventually make its way to one or the other body of water, its destination land that, whenever water is spilled on it, always directs the spilled water to that body.

In some geographical formations it is sometimes impossible to predict, not only the exact destination of the spilled water, but even which body of water it will end up in. This is because the boundary between one basin of attraction and another is riddled with fractal properties; in other words, the boundary at any immediately adjacent point could give the water an entirely different path, velocity, or destination.

In the system posited by the two physicists, this boundary expands to include the whole system: i.e., the entire force field is riddled with fractal properties, and it is impossible to predict even the general destination of the particle given its starting point. Sommerer and Ott make a distinction between this type destination would be predictable but its path and exact destination would not.

There are presumably other such systems because the equation the physicists used to construct the computer model was literally the first one they attempted, and the likelihood that they chose the only equation that would lead to an unstable system is small. If other such systems do exist, "metaphorical examples of riddled be forced to question one of the basic principles that guide their work.

What this question is testing

Local Purpose

Your task

Identify why the author included the referenced detail at that point in the passage — its function, not its content.

Common trap

Answers that merely repeat or summarize the topic of the detail instead of describing the role it plays.

Winning move

Ask what job the detail does for the paragraph, then for the passage's broader point.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
23.

The discussion of the chaos of physical systems is intended to perform which one of the following functions

Answer choices

  1. Term Shift8% picked this

    emphasize the extraordinarily large number of physical irregularities in a riddled

    Sommerer and Ott’s model is riddled with fractal properties (fourth paragraph), but not necessarily physical irregularities.

  2. Term Shift7% picked this

    emphasize the unusual types of physical irregularities found in Sommerer and

    Sommerer and Ott’s model is riddled with fractal properties (fourth paragraph), but not necessarily physical irregularities.

  3. Other Group12% picked this

    emphasize the large percentage of a riddled basin of attraction that

    The purpose is to emphasize the large percentage of Sommerer and Ott’s model that exhibits unpredictability (fourth paragraph).

  4. Correct65% picked this

    emphasize the degree of unpredictability in Sommerer and

    Why this is right

    This is supported in the fourth paragraph.

    Skill tested: Local Purpose · how this choice captures the passage's function is the move to repeat next time.

  5. Unsupported8% picked this

    emphasize the number of fractal properties in a riddled basin

    Riddled basins of attraction are not the subject of the fourth paragraph.

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