Context: Scientists have suggested sending an object into the ergosphere of a black hole  and allow it to accelerate there along the black hole’s direction of rotation

What is an Ergosphere?

• Ergosphere comes from the  Greek word  ‘ergon’, meaning ‘work’.  It got its name because it is possible to get energy and even mass from this place.

• An “ergosphere” is the region in between the event horizon and the stationary limit.

• A “stationary limit” is a surface around the outside of a rotating black hole. 

• Event  Horizon: It is a sphere around the singularity of a Black Hole. When anything enters this sphere, it can’t escape unless it travels faster than light (which is impossible).

• Shape: An Ergosphere is shaped  like an oblate spheroid, or a pumpkin.

• At the top and bottom of the black hole, it touches the event horizon, but as you move the middle part, it goes out farther.Feature:

• It is a bigger sphere surrounding the Event Horizon  that an object can enter and then leave if it’s moving fast enough, but still less than the speed of light

• It is possible to extract matter and energy from the ergosphere, but not from beyond the event horizon.

• Significance: Scientists have suggested a  possibility of  sending  objects into the ergosphere and allow it to accelerate there along the black hole’s direction of rotation, so that it comes out moving faster. This energy ‘gain’ will translate to the black hole losing some angular momentum.

Black hole

• Formation: When a massive star runs out of fuel to fuse, blows up, leaving its core to implode under its weight to form a black hole.

• Einstein’s theory of general relativity: As per it, when a massive star dies, it leaves behind a small, dense remnant core. If the core’s mass is more than about three times the mass of the Sun, the force of gravity overwhelms all other forces and produces a black hole.

• A black hole can only be seen in terms of its effects on its neighborhood as even light cannot escape it.

Event Horizon

• It is a boundary marking the limits of a black hole. At the event horizon, the escape velocity is equal to the speed of light. 

• Since general relativity states that nothing can travel faster than the speed of light, nothing inside the event horizon can ever cross the boundary and escape beyond it, including light. 

• Thus, nothing that enters a black hole can get out or can be observed from outside the event horizon

Gravitational singularity

• It is the centre point of a black hole of infinite density and infinitesimal volume, at which space and time become infinitely distorted according to the theory of General Relativity. A black hole’s great gravitational pull emerges from its singularity.