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About Ergosphere


Ergosphere, a unique feature of rotating black holes, a region outside their outer event horizon.


GS II- Science and Technology

Dimensions of the Article:

  1. About Ergosphere
  2. Key terms
  3. About black hole
  4. Where do black holes come from?

About Ergosphere:

  • The Ergosphere is a region surrounding a rotating black hole where the rotational energy of the black hole is transferred to the surrounding space-time.
  • The label ‘ergosphere’ comes from ‘ergon’, the Greek word for ‘work’.
  • It is named so because it is possible to extract matter and energy from the ergosphere, but not from beyond the event horizon.
  • One interesting feature of the ergosphere is that any object or particle entering this region is forced to rotate along with the black hole’s rotation. This means that within the ergosphere, it is impossible for an object to remain stationary relative to distant observers.

Key terms:

Black Hole: A black hole is formed when a really massive star runs out of fuel to fuse, blows up, leaving its core to implode under its weight to form a black hole.

Gravitational singularity: The black hole’s gravitational pull itself emanates from a point at its centre called the singularity. It is a point where the general theory of relativity breaks down, i.e. where its predictions don’t apply.

Event horizon: The event horizon describes a sphere around the singularity: when anything enters this sphere, it can’t escape unless it travels faster than light (which is impossible).

About black hole

A black hole is a place in space where gravity pulls so much that even light cannot get out. The gravity is so strong because matter has been squeezed into a tiny space, this can happen when a star is dying.

Black holes are of four types, classified on the basis of their mass –

  • Stellar mass black holes,
  • Mid- size black holes ,
  • Super Massive black holes
  • Miniature black holes.

A black hole has two basic parts:

  • The Singularity:  It is at the centre and is where the mass resides.
  • Event Horizon: There is a region of space beyond the black hole called the event horizon. This is a “point of no return”, beyond which it is impossible to escape the gravitational effects of the black hole.

Where do black holes come from?

  • A black hole is formed when stars collapse, leading to a space in the universe with an escape velocity — the speed at which an object must travel to override a planet or an object’s gravitational force.
    • For instance, for a spacecraft to leave the surface of the Earth, it needs to be travelling at a speed of about 40,000 km per hour which is so great that even light cannot escape it.
  • Because light cannot get out, black holes are invisible and can only be tracked with the help of spatial telescopes and special tools.
  • The light cannot go out because the gravity inside a black hole is very strong as a result of a lot of matter being squeezed into a small space.
  • In 2020, the Royal Swedish Academy of Sciences decided to award one half of the year’s Nobel Prize in physics to Roger Penrose and the other half jointly to Reinhard Genzel and Andrea Ghez for furthering the understanding of black holes, the most “enigmatic” objects in the universe.

-Source: The Hindu, The Indian Express

February 2024