Listening to the Universe: The Science of Gravitational Waves Reading Answers

Aug 8, 2025

Listening to the Universe: The Science of Gravitational Waves Reading Answers contain 14 questions and belong to the assessment system of the IELTS General Reading test. Listening to the Universe: The Science of Gravitational Waves Reading Answers must be answered within 20 minutes. In this IELTS reading section, question types include: Write the correct letter, Choose the correct letter, and Choose ONE WORD ONLY for each.

Listening to the Universe: The Science of Gravitational Waves Reading Answers offers a comprehensive overview of gravitational wave astronomy, enabled by sensitive detectors like LIGO and Virgo, opening a new window into the universe by observing space-time ripples caused by massive cosmic events. To practice similar reading tests, candidates can refer to the IELTS Reading Practice Test section.

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Topic:

A.In 2015, a ripple travelled across the cosmos and gently passed through Earth, setting off detectors in Louisiana and Washington, USA. This ripple was not in water, air, or sound—it was in the very fabric of space and time. Known as gravitational waves, these distortions were first predicted by Albert Einstein in 1916 as part of his general theory of relativity. For a century, they remained theoretical, until the Laser Interferometer Gravitational-Wave Observatory (LIGO) recorded the first confirmed signal, caused by the collision of two black holes more than a billion light years away.

B.Gravitational waves are produced when massive celestial objects like black holes or neutron stars accelerate, such as during collisions or mergers. These events are so energetic they cause space-time itself to stretch and squeeze. However, by the time these ripples reach Earth, they are incredibly faint—thousands of times smaller than a proton. Detecting them requires extraordinarily sensitive instruments. LIGO and its European counterpart, Virgo, use laser interferometry to measure changes in distance smaller than one ten-thousandth the diameter of a hydrogen atom.

C.The detection process involves splitting a laser beam along two perpendicular arms, each several kilometers long. When gravitational waves pass through, they distort the lengths of the arms slightly, causing shifts in the interference pattern when the beams are recombined. These changes are then analysed to determine the origin, distance, and cause of the wave. While the technology is mind-boggling, what excites scientists is the potential: gravitational wave astronomy provides a completely new way of observing the universe—one that is not based on light.

D.Traditional telescopes rely on electromagnetic radiation—light, X-rays, radio waves—to observe celestial bodies. However, light can be absorbed, scattered, or blocked by dust and gas. Gravitational waves are not affected in the same way. They pass through matter virtually undisturbed, offering a direct view into some of the most extreme and mysterious parts of the cosmos. For instance, the interiors of black holes, the exact moment of a neutron star merger, and the first seconds after the Big Bang may all be accessible through this new form of detection.

E.The scientific implications are enormous. For one, these detections confirm key aspects of Einstein’s theory. More importantly, they open up possibilities for discovering events never previously observed. Already, gravitational wave observations have led to the discovery of intense black holes, a category that had only been theorised. In 2017, the merger of two neutron stars was detected through gravitational waves and traditional telescopes. This marked the first multi-messenger astronomy event—when both visual and electromagnetic data were used to study the same phenomenon.

F.Despite its promise, gravitational wave astronomy is still in its infancy. LIGO and Virgo can only detect a small portion of events in the universe, and they rely on highly sensitive instruments. Future observatories, like the proposed Einstein Telescope in Europe and LISA (Laser Interferometer Space Antenna) planned by the European Space Agency, aim to detect lower-frequency waves over a broader range of cosmic events. These next-generation tools will allow scientists to detect signals from the early universe—long before galaxies ever formed.

G.The field of gravitational wave astronomy may not only broaden our understanding of the universe but also symbolises a new era in scientific exploration. Much like the transition from viewing the sky to the night sky to detailed screen images, gravitational wave detectors promise a deeper, richer telescopic map of reality. By ‘listening’ to the universe, we’re beginning to uncover cosmic secrets previously hidden in silence.

Questions 27-33

The reading passage has seven paragraphs, A-G. Write the correct letter, A-G.

Which paragraph contains the following information?

27. The comparison between gravitational waves and traditional light-based observation

Answer: D

Supporting statement: “Traditional telescopes rely on electromagnetic radiation... Gravitational waves are not affected in the same way…”

Keywords: [comparison, light-based, gravitational waves, telescopes]

Keyword Location: Paragraph D

Explanation: This paragraph compares gravitational waves with traditional electromagnetic observations, explaining how they differ in their interaction with matter.

28. Description of how gravitational wave detectors work

Answer: C

Supporting statement: “The detection process involves splitting a laser beam along two perpendicular arms…”

Keywords: [detection, how, interferometer, arms]

Keyword Location: Paragraph C

Explanation: The paragraph outlines the working mechanism of gravitational wave detectors using laser interferometry.

29. The extreme sensitivity required to identify gravitational waves

Answer: B

Supporting statement: “...they are incredibly faint—thousands of times smaller than a proton… extraordinarily sensitive instruments.”

Keywords: [faint, sensitive instruments, smaller than proton]

Keyword Location: Paragraph B

Explanation: It discusses the minuscule scale of the waves and the extreme sensitivity needed for detection.

30. The confirmation of a theory made over a hundred years ago

Answer: E

Supporting statement: “These detections confirm key aspects of Einstein’s theory.”

Keywords: [Einstein, confirm, theory]

Keyword Location: Paragraph E

Explanation: Paragraph E states that gravitational wave detection confirms Einstein’s 1916 prediction.

31. How gravitational waves can bypass cosmic obstacles

Answer: D

Supporting statement: “Gravitational waves… pass through matter virtually undisturbed…”

Keywords: [pass through matter, undisturbed, cosmic obstacles]

Keyword Location: Paragraph D

Explanation: This paragraph highlights how gravitational waves can travel through gas and dust, unlike light.

32. The limitations of current detection technology

Answer: F

Supporting statement: “LIGO and Virgo can only detect a small portion of events…”

Keywords: [limitations, current, detection, small portion]

Keyword Location: Paragraph F

Explanation: Paragraph F discusses the limits of present detectors and the need for next-gen observatories.

33. A groundbreaking observation involving two types of signals

Answer: E

Supporting statement: “In 2017, the merger of two neutron stars was detected… This marked the first multi-messenger astronomy event…”

Keywords: [neutron stars, 2017, multi-messenger]

Keyword Location: Paragraph E

Explanation: The paragraph mentions the groundbreaking first instance of combining gravitational and electromagnetic observations.

Question 34

Choose the correct letter, A, B, C, or D.

34. What causes gravitational waves?

A. The rapid expansion of space

B. Movement of any object in space

C. Collisions between massive celestial objects

D. Light reflecting off cosmic dust

Answer: C

Supporting statement: “Gravitational waves are produced when massive celestial objects... collide…”

Keywords: [massive objects, collide, cause waves]

Keyword Location: Paragraph B

Explanation: Collisions between massive bodies like black holes or neutron stars produce gravitational waves.

Question 35

Choose the correct letter.

34. What makes gravitational waves difficult to detect on Earth?

A. They only occur very rarely

B. They are distorted by Earth's atmosphere

C. Their effects are extremely small

D. Most of them travel away from Earth

Answer: C

Supporting statement: “By the time these ripples reach Earth, they are incredibly faint…”

Keywords: [faint, extremely small, detection difficulty]

Keyword Location: Paragraph B

Explanation: The waves’ effects are so tiny upon reaching Earth that detecting them is extremely difficult.

Questions 36-40

Choose ONE WORD ONLY for each.

Gravitational waves are generated when massive objects such as black holes or 36………..

Answer: neutron stars

Supporting statement: “Gravitational waves are produced when massive celestial objects like black holes or neutron stars accelerate...”

Keywords: [gravitational waves, black holes, neutron stars, accelerate]

Keyword Location: Paragraph B

Explanation: The paragraph clearly states that both black holes and neutron stars are sources of gravitational waves when they move rapidly or collide, directly answering the question.

move rapidly or collide. Although these events release immense energy, the effects of gravitational waves are extremely faint when they reach Earth. Instruments like LIGO detect them using 37……………….

Answer: interferometry

Supporting statement: “LIGO and its European counterpart, Virgo, use laser interferometry to measure changes...”

Keywords: [LIGO, Virgo, laser interferometry, measure changes]

Keyword Location: Paragraph B

Explanation: Interferometry is the technique used by gravitational wave detectors to identify minuscule distance changes caused by passing waves.

Beams split into perpendicular arms, and the interference patterns reveal slight distortions in space. Unlike traditional astronomy, which depends on forms of 38……………

Answer: electromagnetic

Supporting statement: “Traditional telescopes rely on electromagnetic radiation—light, X-rays, radio waves...”

Keywords: [electromagnetic radiation, telescopes, traditional astronomy]

Keyword Location: Paragraph D

Explanation: Traditional astronomy depends on various forms of electromagnetic radiation, unlike gravitational wave astronomy.

radiation like visible light, gravitational waves are not affected by gas or dust. This allows scientists to observe violent cosmic phenomena directly. One major achievement was the detection of a neutron star merger in 2017, which marked the first use of 39…………..

Answer: multi-messenger

Supporting statement: “...marked the first multi-messenger astronomy event—when both visual and electromagnetic data were used...”

Keywords: [multi-messenger, 2017, neutron stars, visual and electromagnetic]

Keyword Location: Paragraph E

Explanation: The 2017 event involving a neutron star merger was the first time gravitational waves and electromagnetic signals were observed together, termed “multi-messenger” astronomy.

to study the same event through different data sources. Future missions like LISA will aim to detect gravitational signals from the 40………....

Answer: early

Supporting statement: “...detect signals from the early universe—long before galaxies ever formed.”

Keywords: [detect signals, early universe, galaxies]

Keyword Location: Paragraph F

Explanation: Future observatories like LISA aim to capture gravitational waves from the early universe, offering insights into its formation.

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