International Space Agencies – Missions and Discoveries

Scientists detect Universe’s ‘Noisy’ Gravitational Wave


From UPSC perspective, the following things are important :

Prelims level: Gravitational Wave

Mains level: Not Much

gravitational waves
PC: Hindustan Times

Central Idea

  • Scientists have recently presented compelling evidence suggesting the existence of low-frequency gravitational waves throughout the universe.
  • These waves, ripples in the fabric of space-time, are created by the movement, collision, and merging of massive objects.

What are Gravitational Waves?

  • Einstein’s Theory of General Relativity: In 1915, Einstein proposed a revolutionary theory of gravity, describing it as the curvature of space-time caused by massive objects. According to this theory, objects with mass deform the surrounding space-time, creating a gravitational field.
  • Ripples in the Fabric of Space-time: When massive objects accelerate or experience gravitational forces, they create disturbances in the space-time continuum, propagating as waves. These waves carry energy away from the source and cause a stretching and squeezing effect in space-time.
  • Similarities to Electromagnetic Waves: While gravitational waves differ in nature from electromagnetic waves, they share some fundamental characteristics. Like electromagnetic waves, gravitational waves have properties such as wavelength, frequency, and amplitude.

Detection and Significance

  • Advancements in Technology: Detecting gravitational waves is an intricate scientific endeavor requiring sensitive instruments and precise measurements.
  • Groundbreaking Observations: The first direct detection of gravitational waves occurred in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors. This discovery confirmed the existence of gravitational waves and earned the Nobel Prize in Physics in 2017.
  • Expanding Scientific Frontiers: Gravitational waves provide a new way to study the universe, offering insights into the behavior and properties of massive objects, as well as the nature of space and time itself.
  • Unveiling Cosmic Events: The detection of gravitational waves has opened a new window to observe cataclysmic events, such as the collision of black holes, the merger of neutron stars, and potentially unknown phenomena.
  • Testing General Relativity: Gravitational waves allow scientists to test and refine Einstein’s theory of gravity, probing its limits and providing opportunities for further scientific exploration.

Recent Breakthrough:

Ans. Detection of Low-Frequency Gravitational Waves

  • Radio Astronomy Studies: The research involved the collaboration of five international teams, including the Indian Pulsar Timing Array (InPTA), utilizing six large radio telescopes worldwide, including one in Pune.
  • New Approach: To discover low-frequency gravitational waves, scientists employed a different technology compared to previous studies.
  • Observing Pulsars: Pulsars, rapidly-rotating neutron stars emitting bursts of radiation, were studied as they serve as precise cosmic clocks.
  • Anomalies in Pulsar Signals: Over a period of 15 years, researchers observed 25 pulsars and identified slight variations in the arrival time of their signals. These deviations were attributed to deformities in space-time caused by low-frequency gravitational waves.
  • Large Monster Black Holes: Unlike previously detected ripples, these low-frequency gravitational waves were likely generated by the collision of enormous black holes, millions of times larger than our Sun, typically found at the centers of galaxies.

Significance of the Discovery

  • Long-Awaited Confirmation: Scientists have been searching for low-frequency gravitational waves for decades, considering them to be a perpetual background noise within the universe.
  • Understanding the Universe: The discovery expands our knowledge of the nature and evolution of the universe, shedding light on the environment surrounding massive black holes.
  • Implications for Astrophysics: Gravitational waves offer a new window into the cosmos, enabling scientists to explore phenomena that were previously inaccessible through electromagnetic waves.
  • Cosmic Background Hum: The detection of these waves provides evidence of the large-scale motion of objects in the universe, offering insights into the dynamics and interactions at play.

Solving the mystery

  • Unveiling the Invisible: Gravitational waves allow scientists to perceive previously unobservable phenomena, such as black holes, dark matter, and dark energy.
  • Expanding our Understanding: Analyzing gravitational waves provides insights into the origin, evolution, and structure of galaxies and the universe as a whole.
  • Implications for Spacetime and General Relativity: Einstein’s theory revolutionized our perception of space and time, intertwining them into the concept of spacetime, a flexible and interactive fabric influenced by matter.
  • Answers to Fundamental Questions: Gravitational waves offer a means to explore the mysteries of the cosmos, addressing questions about the formation of galaxies, the nature of gravitational interactions, and the origin of the universe itself.

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