Black Hole

what is black hole?

A black hole is a region in space where the gravitational force is incredibly strong, to the extent that nothing, not even light, can escape from it once it crosses a specific boundary known as the event horizon. These black holes are created when massive stars experience gravitational collapse towards the end of their life cycles. At the core of a black hole lies a singularity, a point of infinite density. Black holes exist in various sizes, ranging from stellar-mass black holes, which are several times more massive than the Sun, to supermassive black holes, which can be millions or even billions of times more massive than the Sun. These supermassive black holes are typically located at the centers of galaxies, including our own Milky Way.

when was black hole discovered?

The notion of black holes has been present for centuries, originating from early concepts in the late 18th century. Nonetheless, the contemporary comprehension of black holes started to develop in the early 20th century with the introduction of Albert Einstein's theory of general relativity, which was published in 1915. Physicist John Archibald Wheeler coined the term "black hole" itself in 1967.

In 1964, the initial potential black hole candidate, Cygnus X-1, was identified through X-ray observations. However, it took some time for astronomers to gather additional evidence to confirm it as a black hole. Since then, numerous black hole candidates have been discovered using various observational techniques, including X-ray and gravitational wave observations.

How big is black hole star?

The dimensions of a black hole are typically defined by its event horizon, which marks the boundary beyond which nothing, not even light, can escape its gravitational force. The size of the event horizon is determined by the mass of the black hole.

For instance, a black hole with a mass equivalent to that of a star, known as a stellar-mass black hole, can have an event horizon ranging from a few kilometers to tens of kilometers in radius. These black holes are relatively small when compared to other celestial bodies like stars or planets.

On the contrary, supermassive black holes, which exist at the cores of galaxies, can possess event horizons with radii spanning from millions to billions of kilometers. These black holes can be millions to billions of times more massive than the Sun.

Therefore, the size of a black hole can vary significantly depending on its mass, ranging from a few kilometers to billions of kilometers in diameter.

What occurs when a black hole star perishes?

The notion of a black hole being "lifeless" is somewhat ambiguous because black holes themselves do not possess life in the conventional sense. Nevertheless, there comes a point in a black hole's lifespan where it can no longer actively gather matter and ceases to emit significant radiation. At this juncture, it could be deemed "inactive" or "dormant."

When a black hole ceases to accumulate matter from its surroundings, it gradually diminishes in mass over incredibly long periods of time due to a phenomenon known as Hawking radiation. This radiation causes the black hole to slowly evaporate, ultimately resulting in its disappearance. However, this process is purely theoretical and has never been directly observed since it occurs over timescales much longer than the current age of the universe for black holes of stellar mass.

Nevertheless, the ultimate fate of supermassive black holes at the cores of galaxies remains uncertain. Some theories propose that they could persist for an exceptionally extended duration, possibly even surpassing the current age of the universe, while others suggest scenarios where they may eventually evaporate through Hawking radiation or merge with other black holes.

Therefore, while a black hole may become "inactive" in terms of its accumulation and radiation, it does not necessarily imply that it is "dead" in the same manner as living organisms.