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TOEFL Experts Reading Practice 36

Reading Section

This section measures your ability to understand academic passages in English. You can skip questions and go back to them later as long as there is time remaining.

Now begin the Reading section.

Reading Section

This section measures your ability to understand academic passages in English. You can skip questions and go back to them later as long as there is time remaining.

Now begin the Reading section.

Dyson Spheres

In the mid-twentieth century, the concept of “Dyson spheres” was introduced because of the growing awareness of the limitations of nonrenewable energy resources. It became apparent to many scientists that fossil fuels stores were decreasing while energy consumption was increasing. They were concerned about the growing possibility that the Earth would one day run out of usable fuel sources. Freeman Dyson, a theoretical physicist and mathematician, published a paper in 1960 that claimed that any energy-consuming civilization would eventually need more energy than its planet could provide, and that the only logical solution would be to capture all the energy emitted by its parent star₁ using Dyson spheres.

Dyson originally found the idea in the 1937 science fiction book Star Maker, written by Olaf Stapledon. This novel describes a fictional history of the universe in which alien civilizations build artificial structures to surround their parent star. These structures, later called Dyson spheres, mine the energy from the star. The fuel from the solar energy far surpasses anything available on a planet. Dyson recognized that the technology needed to create and place a Dyson sphere around the Sun was centuries away. However, he envisioned another practical use. He believed that creating a Dyson sphere would be an inevitable step in any civilization’s development. All sufficiently advanced life forms, including those that originate on other planets, would attempt to create a Dyson sphere. If life exists beyond Earth, and if that life is technologically advanced enough, Dyson reasoned, those life forms must have created a Dyson sphere. If scientists could find that structure, they would find life.

But how can we discover an artificial structure thousands or millions of light years away? That was the question Dyson attempted to answer in his 1960 article. He presented the Dyson sphere as a thought experiment, not as something that humanity should attempt to create, so he did not go into many specifics. In essence, a Dyson sphere is an artificial structure or group of structures that surround a star. Most of the structures are devoted to capturing the star’s solar energy and transforming it into usable energy. The structures, Dyson hypothesized, would block or absorb much of the visible light coming from the star. From the perspective of the Earth, the star would seem to dim. However, the consolidation of all of the star’s energy into the Dyson sphere would result in a measurable increase in infrared radiation. The decreased visible light and increased infrared radiation would significantly alter the star’s emission spectrum₂. Because the emission spectra of stars are easily and regularly monitored from Earth, the effects of the Dyson sphere would be observable. Scouring the heavens for stars with these characteristics would allow astronomers to predict that a Dyson sphere had been created—evidence, he felt, of alien life.

His idea caught on quickly, and searches for Dyson spheres continue to this day. There are currently two stars under investigation that have a reasonable possibility of being surrounded by a Dyson sphere. Several other causes of the anomalies observed in the emission spectra of these two stars have been proposed, but no definitive explanation has emerged. Currently, scientists cannot say definitively why these two stars appear less bright than they should.

Since the original publication, scientists have investigated the practicality of building a Dyson sphere around the Sun. They have ruled out the possibility of a Dyson sphere existing as a solid hollow ball surrounding a star. No known or theoretical material could endure the stress of the star’s gravitational pull. Moreover, without constant correction, it would slowly drift until it collides with the star. To avoid these problems, thousands of smaller structures could be positioned around the Sun. Various theories on how to create and deploy these structures have been proposed. All theories agree, however, that a mass equivalent to all the planets within the inner Solar System—Mercury, Venus, Earth, and Mars—would be needed. Humans would live on the Dyson sphere itself, or on artificially created habitats within the sphere. While this would theoretically solve any energy crisis, it will be a very long time before humans could reasonably consider pursuing this option.

parent star₁: A star that produces a planet’s heat and light, around which the planet orbits (e.g. the Sun is the star of the Earth)

emission spectrum₂: the spectrum of the electromagnetic radiation emitted by a source observable as bands of color on a spectrometer (plural: emission spectra)

Dyson Spheres

→(P1) In the mid-twentieth century, the concept of “Dyson spheres” was introduced because of the growing awareness of the limitations of nonrenewable energy resources. It became apparent to many scientists that fossil fuels stores were decreasing while energy consumption was increasing. They were concerned about the growing possibility that the Earth would one day run out of usable fuel sources. Freeman Dyson, a theoretical physicist and mathematician, published a paper in 1960 that claimed that any energy-consuming civilization would eventually need more energy than its planet could provide, and that the only logical solution would be to capture all the energy emitted by its parent star₁ using Dyson spheres.

Q: The word “eventually” in the passage is closest in meaning to

Ultimately

Immediately

Accidentally

Intentionally

→(P1) In the mid-twentieth century, the concept of “Dyson spheres” was introduced because of the growing awareness of the limitations of nonrenewable energy resources. It became apparent to many scientists that fossil fuels stores were decreasing while energy consumption was increasing. They were concerned about the growing possibility that the Earth would one day run out of usable fuel sources. Freeman Dyson, a theoretical physicist and mathematician, published a paper in 1960 that claimed that any energy-consuming civilization would eventually need more energy than its planet could provide, and that the only logical solution would be to capture all the energy emitted by its parent star₁ using Dyson spheres.

Q: According to paragraph 1, which of the following is something that many scientists are concerned about?

Solutions to the fossil fuels crisis that involve conservation are not being pursued adequately.

Nonrenewable fuel sources will increase in quantity over time.

The Earth may not always have enough fuel to support its demands.

Dyson spheres may not be constructed as soon as they are needed.

→(P2) Dyson originally found the idea in the 1937 science fiction book Star Maker, written by Olaf Stapledon. This novel describes a fictional history of the universe in which alien civilizations build artificial structures to surround their parent star. These structures, later called Dyson spheres, mine the energy from the star. The fuel from the solar energy far surpasses anything available on a planet. Dyson recognized that the technology needed to create and place a Dyson sphere around the Sun was centuries away. However, he envisioned another practical use. He believed that creating a Dyson sphere would be an inevitable step in any civilization’s development. All sufficiently advanced life forms, including those that originate on other planets, would attempt to create a Dyson sphere. If life exists beyond Earth, and if that life is technologically advanced enough, Dyson reasoned, those life forms must have created a Dyson sphere. If scientists could find that structure, they would find life.

Q: The phrase “far surpasses” in the passage is closest in meaning to

Falls far short of

Greatly overpowers

Largely eradicates

Vastly exceeds

→(P2) Dyson originally found the idea in the 1937 science fiction book Star Maker, written by Olaf Stapledon. This novel describes a fictional history of the universe in which alien civilizations build artificial structures to surround their parent star. These structures, later called Dyson spheres, mine the energy from the star. The fuel from the solar energy far surpasses anything available on a planet. Dyson recognized that the technology needed to create and place a Dyson sphere around the Sun was centuries away. However, he envisioned another practical use. He believed that creating a Dyson sphere would be an inevitable step in any civilization’s development. All sufficiently advanced life forms, including those that originate on other planets, would attempt to create a Dyson sphere. If life exists beyond Earth, and if that life is technologically advanced enough, Dyson reasoned, those life forms must have created a Dyson sphere. If scientists could find that structure, they would find life.

Q: In paragraph 2, Freeman Dyson supports his contention that a Dyson sphere could be used to find life beyond Earth by

Reasoning that Dyson spheres must already exist elsewhere in the universe

Indicating that Dyson spheres would be the primary artificial structures created by other life forms

Presenting a rationale for why alien life forms would likely try to create a Dyson sphere

Contrasting Dyson spheres with other potential means of technologically advanced energy extraction

→(P2) Dyson originally found the idea in the 1937 science fiction book Star Maker, written by Olaf Stapledon. This novel describes a fictional history of the universe in which alien civilizations build artificial structures to surround their parent star. These structures, later called Dyson spheres, mine the energy from the star. The fuel from the solar energy far surpasses anything available on a planet. Dyson recognized that the technology needed to create and place a Dyson sphere around the Sun was centuries away. However, he envisioned another practical use. He believed that creating a Dyson sphere would be an inevitable step in any civilization’s development. All sufficiently advanced life forms, including those that originate on other planets, would attempt to create a Dyson sphere. If life exists beyond Earth, and if that life is technologically advanced enough, Dyson reasoned, those life forms must have created a Dyson sphere. If scientists could find that structure, they would find life.

Q: The word “inevitable” in the passage is closest in meaning to

Unavoidable

Incredible

Unremarkable

Insurmountable

→(P3) But how can we discover an artificial structure thousands or millions of light years away? That was the question Dyson attempted to answer in his 1960 article. He presented the Dyson sphere as a thought experiment, not as something that humanity should attempt to create, so he did not go into many specifics. In essence, a Dyson sphere is an artificial structure or group of structures that surround a star. Most of the structures are devoted to capturing the star’s solar energy and transforming it into usable energy. The structures, Dyson hypothesized, would block or absorb much of the visible light coming from the star. From the perspective of the Earth, the star would seem to dim. However, the consolidation of all of the star’s energy into the Dyson sphere would result in a measurable increase in infrared radiation. The decreased visible light and increased infrared radiation would significantly alter the star’s emission spectrum₂. Because the emission spectra of stars are easily and regularly monitored from Earth, the effects of the Dyson sphere would be observable. Scouring the heavens for stars with these characteristics would allow astronomers to predict that a Dyson sphere had been created—evidence, he felt, of alien life.

Q: The word “perspective” in the passage is closest in meaning to

Rotation

Viewpoint

Dimension

Reverence

→(P3) But how can we discover an artificial structure thousands or millions of light years away? That was the question Dyson attempted to answer in his 1960 article. He presented the Dyson sphere as a thought experiment, not as something that humanity should attempt to create, so he did not go into many specifics. In essence, a Dyson sphere is an artificial structure or group of structures that surround a star. Most of the structures are devoted to capturing the star’s solar energy and transforming it into usable energy. The structures, Dyson hypothesized, would block or absorb much of the visible light coming from the star. From the perspective of the Earth, the star would seem to dim. However, the consolidation of all of the star’s energy into the Dyson sphere would result in a measurable increase in infrared radiation. The decreased visible light and increased infrared radiation would significantly alter the star’s emission spectrum₂. Because the emission spectra of stars are easily and regularly monitored from Earth, the effects of the Dyson sphere would be observable. Scouring the heavens for stars with these characteristics would allow astronomers to predict that a Dyson sphere had been created—evidence, he felt, of alien life.

Q: The words “these characteristics” in the passage refer to

Effects of the consolidation of the star into the Dyson sphere

Energy transformed from infrared radiation to visible light

Decreased fuel stocks and increased energy consumption

Increased infrared radiation and decreased visible light

→(P3) But how can we discover an artificial structure thousands or millions of light years away? That was the question Dyson attempted to answer in his 1960 article. He presented the Dyson sphere as a thought experiment, not as something that humanity should attempt to create, so he did not go into many specifics. In essence, a Dyson sphere is an artificial structure or group of structures that surround a star. Most of the structures are devoted to capturing the star’s solar energy and transforming it into usable energy. The structures, Dyson hypothesized, would block or absorb much of the visible light coming from the star. From the perspective of the Earth, the star would seem to dim. However, the consolidation of all of the star’s energy into the Dyson sphere would result in a measurable increase in infrared radiation. The decreased visible light and increased infrared radiation would significantly alter the star’s emission spectrum₂. Because the emission spectra of stars are easily and regularly monitored from Earth, the effects of the Dyson sphere would be observable. Scouring the heavens for stars with these characteristics would allow astronomers to predict that a Dyson sphere had been created—evidence, he felt, of alien life.

Q: Which of the sentences below best expresses the essential information in the highlighted sentence in paragraph 3? Incorrect choices change the meaning in important ways or leave out essential information.

The Dyson sphere was intended as a broad thought experiment, but Dyson provided specific instructions for how to create one.

In his article, Dyson described the Dyson sphere vaguely because it was meant as a concept to explore, not a plan to carry out.

Dyson presented the Dyson sphere as an experimental plan, one that he expected others to make more precise but not to execute.

The answer Dyson gave about Dyson spheres was a thought experiment that humanity should not attempt to create without specifics.

→(P4) His idea caught on quickly, and searches for Dyson spheres continue to this day. There are currently two stars under investigation that have a reasonable possibility of being surrounded by a Dyson sphere. Several other causes of the anomalies observed in the emission spectra of these two stars have been proposed, but no definitive explanation has emerged. Currently, scientists cannot say definitively why these two stars appear less bright than they should.

Q: According to paragraph 4, what is true about the two stars currently under investigation?

They are surrounded by Dyson spheres.

They appear less dim than they should.

Their emission spectra have not been conclusively explained.

They have been investigated more than most other stars.

→(P4) His idea caught on quickly, and searches for Dyson spheres continue to this day. There are currently two stars under investigation that have a reasonable possibility of being surrounded by a Dyson sphere. Several other causes of the anomalies observed in the emission spectra of these two stars have been proposed, but no definitive explanation has emerged. Currently, scientists cannot say definitively why these two stars appear less bright than they should.

Q: In paragraph 4, why does the author mention the “two stars under investigation”?

To illustrate how Dyson’s theory is still relevant and inspiring

To contend that these two stars probably have Dyson spheres surrounding them

To suggest that Dyson spheres around these stars may one day provide us energy

To explain why a Dyson sphere is less likely to be possible at present for our own star

→(P5) Since the original publication, scientists have investigated the practicality of building a Dyson sphere around the Sun. They have ruled out the possibility of a Dyson sphere existing as a solid hollow ball surrounding a star. No known or theoretical material could endure the stress of the star’s gravitational pull. Moreover, without constant correction, it would slowly drift until it collides with the star. To avoid these problems, thousands of smaller structures could be positioned around the Sun. Various theories on how to create and deploy these structures have been proposed. All theories agree, however, that a mass equivalent to all the planets within the inner Solar System—Mercury, Venus, Earth, and Mars—would be needed. Humans would live on the Dyson sphere itself, or on artificially created habitats within the sphere. While this would theoretically solve any energy crisis, it will be a very long time before humans could reasonably consider pursuing this option.

Q: According to paragraph 5, all of the following are considered challenges to building a Dyson sphere EXCEPT:

The stress on a hollow ball structure caused by the star’s gravitational pull

The drift of a hollow ball structure

The quantity of mass that would be required

The ability of humans to live on a Dyson sphere

Q: In paragraph 5, the solid hollow-ball structure is mentioned to illustrate

The possible existence of Dyson spheres outside the solar system

The potential difficulties of creating a Dyson sphere

The effects of a Dyson sphere on the star it surrounds

The amount of mass needed to create a Dyson sphere

In paragraph 3 of the passage, there is a missing sentence. The paragraph is repeated below and shows four letters [A], [B], [C], and [D] that indicate where the following sentence could be added.

The increase in energy available to a civilization using the Dyson sphere would be exponential.

Where would the sentence best fit?

→(P3) But how can we discover an artificial structure thousands or millions of light years away? That was the question Dyson attempted to answer in his 1960 article. He presented the Dyson sphere as a thought experiment, not as something that humanity should attempt to create, so he did not go into many specifics. In essence, a Dyson sphere is an artificial structure or group of structures that surround a star.[A] Most of the structures are devoted to capturing the star’s solar energy and transforming it into usable energy.[B] The structures, Dyson hypothesized, would block or absorb much of the visible light coming from the star. From the perspective of the Earth, the star would seem to dim. [C]However, the consolidation of all of the star’s energy into the Dyson sphere would result in a measurable increase in infrared radiation.[D] The decreased visible light and increased infrared radiation would significantly alter the star’s emission spectrum₂. Because the emission spectra of stars are easily and regularly monitored from Earth, the effects of the Dyson sphere would be observable. Scouring the heavens for stars with these characteristics would allow astronomers to predict that a Dyson sphere had been created—evidence, he felt, of alien life.

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Dyson spheres were introduced in response to growing concerns about increased energy consumption on Earth.

A Dyson sphere is an artificial structure that surrounds a star, capturing as much of that star’s energy as possible.

In order to create a Dyson sphere around our sun, the planets Mercury, Venus, Earth, and Mars would all have to be used up.

While it may one day be possible to build a Dyson sphere around the Earth’s sun, they were proposed—and remain significant today—as a theoretical abstraction.

The genesis of the concept of Dyson spheres in science fiction illustrates that scientific ideas and progress can grow from unexpected sources.

Causes other than Dyson spheres may explain the anomalies in the emission spectra of two stars currently under observation.

If a Dyson sphere surrounded a star visible from Earth, the star’s altered emission spectrum would allow scientists to theorize that life existed elsewhere.

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