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Gravitational Lensing:

GS Paper 3:

Topics Covered: Developments in Science and Technology.



This article forms a part of The Hindu’s Science for All newsletter, which explains all things Science, without the jargon.


What is gravitational lensing? How does it work?

  • Gravitational lensing is an effect of Einstein’s theory of general relativity – simply put, mass bends light.
  • The gravitational field of a massive object will extend far into space, and cause light rays passing close to that object (and thus through its gravitational field) to be bent and refocused somewhere else.
  • The more massive the object, the stronger its gravitational field and hence the greater the bending of light rays – just like using denser materials to make optical lenses results in a greater amount of refraction.


Current Affairs



  • Gravitational lensing is useful to cosmologists because it is directly sensitive to the amount and distribution of dark matter.
  • Lensing can help astronomers work out exactly how much dark matter there is in the Universe as a whole and also how it is distributed.
  • Lensing has also been used to help verify the existence of dark matter itself.


Insta Curious:

Gravity is one of the weaker forces in nature, if you consider the strength of the electromagnetic force, which acts between charged, magnetic particles like the electron, or the strong nuclear force, which acts between components of the atomic nucleus, such as the protons and neutrons.



Prelims Link:

  1. Gravitational Lensing.
  2. Gravity.
  3. Galaxy.
  4. Electromagnetic force.
  5. Light waves.
  6. Light years.

Mains Link:

Discuss the significance of Gravitational Lensing.

Sources: the Hindu.