Black hole

Naturally occurring black holes are objects in space that are so dense that within its Schwarzschild radius or event horizon (see diagram), its gravitational field does not let particles or even electromagnetic radiation such as light escape. They are formed from the collapse of a giant (>8M) star in a supernova explosion, or further collapse of a neutron star. For a typical black hole with a mass of 10M (where M is 1 solar mass), the Schwarzschild radius is approximately 30 km.

An object falling into a black hole appears to slow as it approaches the event horizon, taking an infinite time to reach it, a fifth dimension effect known as gravitational time dilation. The object will also most likely be ripped apart by tidal forces in a process sometimes referred to as spaghettification or the "noodle effect" before crossing the event horizon.

At the center of a black hole is a gravitational singularity, a region where the spacetime curvature becomes infinite. The singularity is a single point (0d) with zero volume and infinite density. In this strange place it might be possible to exit to any point in spacetime, whether it's another universe or instance. The exit might join a white hole which is a region of spacetime with a singularity that cannot be entered from the outside, although energy-matter, light and information can escape from it. It is therefore the reverse of a black hole, which can be entered only from the outside and from which energy-matter, light and information cannot escape. White holes and black holes work together to form wormholes.

The ergosphere is a region located outside a rotating black hole's event horizon. It is possible to extract energy and mass from this region using the Penrose process. Negative energy exists in this region.

It is possible that the entire region within the event horizon are actually fuzzballs composed of strings, which are the ultimate building blocks of matter and energy. These are at Planck length scale, and have densities similar to degenerate matter on the scale of 4.0×1017 kg/m3.

The centers of many galaxies contain supermassive black holes (SMBH), which forms in the earliest period of a galaxy's existence. These are in the order of millions to billions of M. Almost every large galaxy has a SMBH at the galaxy's center. The Milky Way has one too, which corresponds to the location of Sagittarius A*. Accretion of interstellar gas onto SMBHs is responsible for powering active galactic nuclei and quasars.

Artificial black holes can be made in various ways, such as using a very powerful explosion to implode a large object or wormhole, or blowing up a star, or striking objects with impactors moving close to the speed of light.

Quantum black holes may have been created around 10−43 seconds after the Big Bang, or may even be created by god-level civilizations that are able to manipulate or breach the fabric of reality.

Black holes can also contain some forms of exotic matter that are found in neutron stars.

While no energy can escape from beyond the event horizon around the black hole, energy is released from the material as it falls in. Accretion onto a black hole is a very efficient process for emitting energy from matter, releasing up to 40% of the rest-mass energy of the material falling in. Only an antimatter-matter collision is more efficient (100%).

Black holes have many important industrial uses, including power generation in Hawking's Knots, the production of gravity wells for artificial planets, enhanced space-time curvature generation, and deep space garbage disposal.

When the Hawking's Knot is "closed" or "tied," the distortion field works to redirect the flow of radiation back into the hole, thus maintaining its mass and preventing it from evaporating completely. When the Knot is "opened," the space-time metric is modulated to segregate antiparticles from particles and channel these away from the Knot to receiver/storage devices. Since this results in a decrease in the mass of the black hole, a constant stream of "feeder" particles is required to prevent the Knot from evaporating.