Q. Which one of the following statements is correct regarding ‘Ergosphere’?

[A] It is a region around a black hole where photons (light particles) can orbit the black hole in a circular path.

[B] It is a region found outside the event horizon of a rotating black hole, where the black holes immense gravity drags spacetime itself along with its rotation.

[C] It is the central point within a black hole where matter is infinitely dense and gravitational forces are infinitely strong.

[D] It is the closest orbit around a black hole where an object can stably orbit without eventually spiraling into the black hole.

Answer: B
Notes:

Explanation – The ergosphere is an oblate spheroid-shaped region surrounding a rotating black hole, also known as a Kerr black hole. In this region, the black hole’s immense gravity causes the spacetime to rotate along with it. This phenomenon is known as the “frame-dragging” or “Lense-Thirring effect.” Inside the ergosphere, it is impossible for any particle to remain stationary with respect to the outside universe; all particles are inevitably drawn into the rotation of the black hole. It is the region in between the event horizon and the stationary limit. Objects within the ergosphere are forced to rotate along with the black hole’s spin due to the distortion of spacetime caused by its immense gravitational pull.

Source: Forum IAS

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